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L-carnitine

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Also listed as: Carnitine, Acetyl-L-carnitine, Propionyl-L-carnitine
Related terms
Background
Evidencetable
Tradition
Dosing
Safety
Interactions
Attribution
Bibliography

Related Terms
  • AcCn, acetyl-L-carnitine, B (t) Factor, beta-hydroxy-gamma-N-trimethylamino butyrate, canitor, Carnilean®, carnitene, carnitor, D-carnitine, D,L-carnitine, glycine propionyl-L-carnitine (GPLC), Godex®, Intralipid®, L-3-hydroxytrimethylamminobutanoate, LAC, L-acetyl-carnitine, L-Carnipure®, L-carnitina (Spanish), L-carnitine L-tartrate, LCLT, levacecarnine, levocarnitine, levocarnitine chloride, LK-80, L-propionylcarnitine, MMXT, propionil-L-carnitine, propionyl-L-carnitine, ST200, ST261, VitaCarn®, vitamin B(t), vitamin Bt.
  • Selected combination product: Carnidrop® (Sigma Tau, Pomezia, Italy; L-carnitine 1%, taurine 0.50%, and sodium hyaluronate 0.20g/100mL), Fertimev® (L-arginine, L-carnitine, acetyl-L-carnitine, and ginseng extracts), Optive® (Allergan, Rome, Italy; L-carnitine 0.258%, glycerine 0.9%, an unspecified amount of erythritol, and sodium carboxy methyl cellulose 0.5%), PhenCal (phenylalanine, tryptophan, glutamine, pyridoxal-5'-phosphate, chromium picolinate, carnitine).
  • Note: This bottom line monograph focuses on supplemental sources of carnitine, and not the forms of carnitine that are made in the body. Unless otherwise stated, the use of the term carnitine in this bottom line monograph refers to levocarnitine (L-carnitine) and not D-carnitine, which may cause secondary deficiency.

Background
  • The main function of L-carnitine is to transfer certain molecules across cell membranes so that they can be broken down and used by the body. In humans, L-carnitine is made in the liver, kidney, and brain, and is transported to other areas of the body.
  • Supplementation may be needed in rare cases of primary carnitine deficiency. Deficiency may be caused by defects in carnitine production or transport, or in a defect in the kidney's ability to conserve carnitine in the body.
  • L-carnitine may be effective for some conditions caused by L-carnitine deficiency, including long-term chest pain and pain in the legs due to blocked blood flow. Another condition that may benefit from carnitine supplementation is decreased sperm movement.
  • Carnitine supplementation has been studied in premature babies for maintaining or increasing carnitine levels and possibly weight gain. However, carnitine is not often added to nutrition for these babies. Soy-based infant formulas are fortified with carnitine to levels found in breast milk.
  • Carnitine supplementation, as L-carnitine, or acetyl- or propionyl-L-carnitine, has been studied for many other conditions. However, there is a lack of strong evidence for these uses.
  • D-carnitine or DL-carnitine may cause secondary L-carnitine deficiency and should not be used.

Evidence Table

These uses have been tested in humans or animals. Safety and effectiveness have not always been proven. Some of these conditions are potentially serious, and should be evaluated by a qualified healthcare provider. GRADE *


Carnitine deficiency may result in metabolism problems, including genetic disorders. Carnitine has been used as part of a treatment plan for carnitine deficiency, metabolism problems, and carnitine uptake defects.

A


Primary carnitine deficiency is a genetic condition, while secondary deficiency is caused by other factors. Carnitine taken by mouth or injected into the vein has been used for both primary and secondary carnitine deficiency. For primary deficiency, L-carnitine has been found to restore levels of carnitine to nearly normal in the body. Carnitine has also been used as part of a treatment plan for many other disorders caused by deficiency, including reduced carnitine transport and weakening of the heart muscle.

A


Studies show that propionyl-L-carnitine and L-carnitine may be effective for peripheral vascular disease. There is strong evidence to support their use in cases of severe circulation problems in the legs. However, it is unclear whether they may be as effective for blood vessel diseases caused by diabetes and clogged arteries. More studies are also needed to compare the effectiveness of propionyl-L-carnitine and other treatments.

A


Carnitine may benefit people who have autism. However, more research is needed before firm conclusions can be made on the use of carnitine for this condition.

B


Evidence suggests that L-carnitine and propionyl-L-carnitine are effective for reducing chest pain symptoms. They may also increase exercise tolerance. More high-quality studies are needed in this area.

B


Taking carnitine by mouth has been shown to increase blood levels of carnitine in people undergoing hemodialysis. It may also promote red blood cell survival, improve quality of life, and decrease inflammation. Carnitine has also been studied for side effects of hemodialysis, such as muscle cramping and low blood pressure. L-carnitine may have heart health benefits in people with end-stage kidney disease. However, more research is needed to confirm these findings.

B


Evidence suggests that L-carnitine may improve quality of life and mental function in people with confused thinking due to liver disorders. More research is needed to determine appropriate doses and timing.

B


Evidence suggests that carnitine and/or acetyl-L-carnitine may increase sperm movement and pregnancy rates. However, evidence is limited and more research is needed to determine appropriate dosing and duration.

B


L-carnitine has been studied for abnormal heart rhythms, with promising early results. However, further research is needed before conclusions can be made.

C


Limited study has found promising results for L-carnitine use in boys with attention-deficit hyperactivity disorder (ADHD). However, some conflicting evidence has been found. More research is needed to make a firm conclusion.

C


Carnitine may have positive effects on body composition, mental and physical function, and fatigue in older people. More research is needed in this field.

C


L-carnitine has been studied for use in people who have AIDS. Early studies suggest that carnitine may benefit these people, but conflicting evidence exists. More studies are needed to make a firm conclusion.

C


Early study suggests that L-carnitine or acetyl-L-carnitine (ALC) may benefit alcoholics. More research is needed before firm conclusions can be made in this field.

C


Limited evidence suggests that a combination product containing acetyl-L-carnitine may improve alertness in college students. Further research is needed.

C


Early studies suggest that L-carnitine and/or acetyl-L-carnitine may benefit people who have Alzheimer's disease. A combination product containing acetyl-L-carnitine and other nutrients appeared to slow mental decline significantly, as well as improve mental performance. However, conflicting results exist. More research is needed before conclusions can be made in this field.

C


L-carnitine has been studied for amenorrhea, with promising early results. However, further research is needed to confirm these findings.

C


Carnitine may benefit children who have joint pain associated with psoriasis, a long-term skin condition causing scaly patches. Further research is needed before conclusions can be made.

C


Beta-thalassemia is a disorder that affects the production of hemoglobin, the protein that carries oxygen in the blood. Carnitine levels have been found to be lower in people with this disorder. Although there is some evidence of benefit of carnitine treatment in this population, studies are limited and the effect of carnitine alone is unclear. More research is needed before conclusions can be made.

C


Acetyl-L-carnitine has been studied as part of a treatment plan for brain injuries in professional football players. However, the effect of carnitine alone is unclear, and further research is needed before conclusions can be made.

C


Early research has found a lack of effect of carnitine on fatigue, energy, and lean body mass in people with cachexia due to cancer. More research is needed before conclusions can be made.

C


Carnitine has been studied as part of a treatment plan for cancer of the pancreas and thyroid. However, the effect of carnitine alone is unclear, and further research is needed before conclusions can be made.

C


Limited research suggests a positive effect of acetyl-L-carnitine on blood flow to the brain and metabolism of the brain in people who have had a stroke. More studies are needed in this area.

C


Early evidence suggests a potential benefit from carnitine in people with chronic fatigue syndrome. However, there are some conflicting results. Further research is needed before conclusions can be made.

C


Most available studies on carnitine for dementia are of low quality. Early results are promising, but there is a lack of evidence at this time to support the use of acetyl-L-carnitine for dementia. More research is needed before conclusions can be made.

C


Carnitine has been studied for the treatment of depression, with promising early results. However, further research is needed to confirm these findings.

C


Limited study suggests that L-carnitine may benefit people with type 2 diabetes. Other research has found that carnitine may lower blood sugar. However results are not consistent. Further research is needed before a firm conclusion can be made.

C


Early evidence suggests that acetyl-L-carnitine may benefit people who have diabetic nerve damage. However, further research is needed before conclusions can be made.

C


Continuous ambulatory peritoneal dialysis (CAPD) is a treatment for severe, long-term kidney dysfunction. This treatment does not require a machine. Limited research has looked at the effect of L-carnitine in people undergoing CAPD. More high-quality studies are needed in this area.

C


Early evidence suggests that carnitine may benefit people who have diphtheria, especially in terms of reducing heart muscle damage. More research is needed to confirm these results.

C


Early evidence suggests that acetyl-L-carnitine may lack benefit in people with Down's syndrome. More research is needed.

C


Early evidence suggests that acetyl-L-carnitine may benefit people with withdrawal from opiates. More research is needed.

C


Eye drops containing carnitine and other ingredients have been studied in people with dry eyes. More research is needed in this area.

C


Some studies suggest that the use of valproic acid may lower carnitine levels in some people. Carnitine has been used as part of a treatment plan for toxicity associated with valproic acid. According to some research, carnitine is the recommended treatment for liver injury caused by valproic acid. Acetyl-L-carnitine has been studied for reducing nerve damage of HIV. Carnitine has also been studied for chemotherapy side effects. Further study is needed in this area.

C


Early studies suggest that propionyl-L-carnitine, with acetyl-L-carnitine or sildenafil, may benefit people with erectile dysfunction (ED). However, more research is needed in this area.

C


Overall, evidence is mixed on the use of L-carnitine for exercise performance. More research is needed before a firm conclusion can be made.

C


Early evidence is promising on the use of L-carnitine for fatigue. However, available studies are of low quality. Further research is needed to confirm these findings.

C


Early evidence suggests that carnitine may benefit people who have fibromyalgia. Further research is needed.

C


There is a lack of evidence to support the use of carnitine in the treatment of hyperactive behavior in children with fragile-X syndrome. More research is needed.

C


Early study suggests that carnitine may increase hair growth in people with mild-to-moderate male-pattern baldness. More research is needed before conclusions can be made.

C


Carnitine has been studied for heart attacks. However, evidence is lacking at this time. More research is needed in this area.

C


Carnitine has been studied with other agents for improving blood pressure in people with heart disease. Although benefits have been found on abnormal heart rhythms and chest pain, available studies are limited. Further research is needed.

C


Carnitine may reduce heart disease risk factors in healthy people and in those with type 2 diabetes. However, there are some mixed results. Carnitine also appears to have mixed results in people undergoing treatment for kidney dysfunction, although some evidence suggests it may reduce inflammation. More research is needed.

C


Evidence is mixed in terms of the effects of carnitine use for heart failure. Currently there is a lack of strong evidence to support the use of carnitine for this condition. Further research is needed before conclusions can be made.

C


L-carnitine use may benefit people who have heart muscle injury caused by carbon monoxide poisoning. More research is needed in order to confirm these early findings.

C


Limited evidence suggests that acetyl-L-carnitine may lack effect in people who have Huntington's disease. More research is needed before conclusions can be made.

C


Limited studies have looked at the use of carnitine for lactic acidosis. Evidence is lacking at this time and more research is needed.

C


Early study suggests a lack of effect of propionyl-L-carnitine on reducing the size of leg ulcers. Further study is needed.

C


Carnitine has been studied for the treatment of high lipids in the blood. Although early evidence is promising, more research is needed in this field.

C


Limited studies have looked at the use of carnitine for liver disease. Although there are promising early results, more research is needed.

C


Carnitine may benefit people who have long-term hepatitis C, a viral disease that causes liver inflammation. L-carnitine may also reduce fatigue in this population. However, further research is needed before conclusions can be made.

C


Limited study has looked at the use of carnitine for memory. However, effects appeared to be lacking unless carnitine was taken with a glucose drink. More research is needed before a conclusion can be made.

C


Carnitine has been used as part of a treatment regimen in pregnant women with metabolic abnormalities, as well as in siblings or infants with gene mutations. However, the benefits are unclear, and further studies are needed.

C


L-carnitine has been found to decrease migraine frequency and severity. However, it has been found to be less effective than magnesium. When used with magnesium, the combination was less effective than magnesium alone. Further study is needed.

C


Mitochondria are parts of the cell that produce energy. Carnitine has been used as part of a treatment plan for various mitochondrial disorders. However, further research is needed.

C


There is a lack of evidence to support the use of carnitine in people with fatigue due to multiple sclerosis. Further research is needed.

C


A combination of valproate and L-carnitine lacked benefit on muscle wasting/weakness in the spine, in early research. Further study on carnitine alone is needed.

C


It is unclear at this time whether carnitine may have an effect on nutritional deficiencies in adults. More research is needed.

C


It is unclear whether full-term babies receiving nutrition injected into the vein need additional carnitine. For long-term feeding with soy formula, carnitine may be added to levels found in breast milk. However, it is unclear what effect carnitine may have on weight gain. Further study is needed.

C


It is unclear whether premature babies receiving nutrition injected into the vein need additional carnitine. Some evidence suggests that additional carnitine may cause side effects in terms of weight gain. Because of this, carnitine is not advised in low-birth weight infants, without evidence of need. For long-term feeding with soy formula, carnitine may be added to levels found in breast milk. However, It is unclear what effect carnitine may have on weight gain. Further studies are needed.

C


Although there is evidence of benefit of acetyl-L-carnitine for nerve damage, studies have found conflicting results. Further research is needed for strong conclusions to be formed.

C


Acetyl-L-carnitine has been studied for reducing pain and slowing disease progression in men with Peyronie's disease. Propionyl-L-carnitine has also been studied in combination with verapamil. More research is needed before making conclusions for the use of carnitine for Peyronie's disease.

C


Limited research has looked at the use of carnitine for threatened miscarriage. Further study is needed in this field.

C


Limited research has looked at the use of carnitine for respiratory distress in adults. As yet, there is a lack of evidence to support the use of carnitine for this condition.

C


Limited research has looked at the use of carnitine for respiratory distress in infants. As yet, there is a lack of evidence to support the use of carnitine for this condition.

C


Limited studies have shown promising results for the use of carnitine for treating Rett's syndrome. More research is needed before strong conclusions can be made.

C


Acetyl-L-carnitine may reduce back and leg pain caused by a herniated disc. Further research is needed before conclusions may be made.

C


Early evidence suggests a lack of effect of propionyl-L-carnitine on sickle cell disease. More studies are needed before conclusions can be made.

C


Evidence on the use of carnitine in improving heart muscle function during open-heart surgery is mixed. Currently, there is not enough evidence to support the use of carnitine for this purpose.

C


Limited evidence is available on the use of carnitine for systemic lupus erythematosus. Further research is required.

C


Carnitine has been studied for overactive thyroid, but evidence is lacking to support its use at this time. More research is needed.

C


Early study suggests that antibacterial activity may be increased in people with tuberculosis who are given acetyl-L-carnitine. More studies are needed before conclusions can be made.

C


Propionyl-L-carnitine tablets taken by mouth have been studied for the treatment of ulcerative colitis. Further research is needed in this area.

C


Limited evidence suggests that L-carnitine may lack effect on weight loss in obese people. Further studies are needed before conclusions can be made.

C
* Key to grades

A: Strong scientific evidence for this use
B: Good scientific evidence for this use
C: Unclear scientific evidence for this use
D: Fair scientific evidence for this use (it may not work)
F: Strong scientific evidence against this use (it likley does not work)


Tradition / Theory

The below uses are based on tradition, scientific theories, or limited research. They often have not been thoroughly tested in humans, and safety and effectiveness have not always been proven. Some of these conditions are potentially serious, and should be evaluated by a qualified healthcare provider. There may be other proposed uses that are not listed below.

  • Acne, amyotrophic lateral sclerosis (disease of nerve cells in brain and spinal cord), antioxidant, appetite stimulant, blood circulation, blood disorders (caused by kidney disease), cancer (carnitine deficiency), chronic lung conditions, diabetic complications, dizziness, encephalopathy (brain disease), eye disorders, high blood pressure, immune function, immune system regulation, inborn errors of urea synthesis (a genetic disorder causing problems with ammonia breakdown), kidney disease, knee osteoarthritis, lung diseases, macular degeneration (eye disease causing vision loss), mental disorders, metabolic disorders, movement disorders, muscle and joint disorders, muscle weakness (aging), myocarditis/endocarditis (heart infections), myopathy (muscle disease), nerve disorders (children), nervous system disorders, organ transplantation (liver), pain, Parkinson's disease, proteinuria (protein in the urine), ringing in the ears, seizure disorders, skin conditions, vitamin B12 deficiency.

Dosing

Adults (18 years and older)

  • General: Doses of carnitine injected into the vein vary depending on the person and their condition. Supplementation should be 2-5 milligrams per kilogram daily and be given with the same technique with which nutrients are given. Some sources suggest 50-100 milligrams per kilogram daily for the removal of toxic compounds from the body.
  • For aging, 2 grams of carnitine has been taken by mouth daily for up to six months.
  • For AIDS, 6 grams of L-carnitine has been taken by mouth daily for two weeks.
  • For alcoholism (abstinence), 1-3 grams of acetyl-L-carnitine has been injected into the vein once daily for 10 days, followed by 3 grams taken by mouth three times daily for 80 days.
  • For alcoholism (memory), 2 grams of acetyl-L-carnitine has been taken by mouth daily for 90 days.
  • For Alzheimer's disease, 1-3 grams of acetyl-L-carnitine has been taken by mouth daily in up to four divided doses for up to 12 months.
  • For absent menstrual period, 1 gram of acetyl-L-carnitine has been taken by mouth daily for 16 weeks.
  • For long-term chest pain, 1.5-2 grams of L-carnitine and propionyl-L-carnitine has been taken by mouth daily for up to one month. A single dose of 15 milligrams per kilogram of propionyl-L-carnitine has been taken by mouth. Doses of 20-40 milligrams per kilogram of DL-carnitine have been injected into the vein.
  • For autism, liquid L-carnitine has been taken by mouth in a dose of 50 milligrams per kilogram daily for three months.
  • For weight loss caused by disease, 4 grams of L-carnitine has been taken by mouth daily for four months, without evidence of benefit. Four grams of L-carnitine has been taken by mouth daily.
  • For cancer, doses of carnitine ranging from 250-3,000 milligrams have been taken by mouth in two daily doses for one week. A dose of 6 grams has been taken by mouth daily in three single doses (Carnitene®) during or after meals for four weeks. A dose of 4 grams of L-carnitine has been taken by mouth daily for seven days. Doses of 250-1,750 milligrams of L-carnitine have been taken by mouth daily for one week.
  • For heart protection from chemotherapy agents, 3 grams of L-carnitine has been taken by mouth before each chemotherapy cycle, followed by 1 gram of carnitine daily for 21 days, without evidence of benefit.
  • For heart disease, L-carnitine 2-14 grans has been taken by mouth or injected into the vein 1-3 times daily.
  • For heart disease risk, 2 grams of L-carnitine has been taken by mouth daily in two doses for 3-12 weeks. A dose of 600 milligrams of propionyl-L-carnitine has been injected into the vein three times weekly for 12 months.
  • For long-term fatigue, 2 grams of acetyl-L-carnitine has been taken by mouth twice daily for 180 days.
  • For heart failure, 1.5 grams of propionyl-L-carnitine or 2 grams of L-carnitine has been taken by mouth daily for up to three years. A dose of 1 gram of L-carnitine has been taken by mouth three times daily for 120 days. A dose of 1.5 grams of carnitine has been taken by mouth daily for three months.
  • For depression, 1.5-500 grams of acetyl-L-carnitine has been taken by mouth 1-2 times daily for up to 12 weeks.
  • For diabetes, 3 grams of L-carnitine has been taken by mouth daily for up to 12 weeks, with a lack of evidence of benefit. A dose of 2 grams of carnitine has been taken by mouth daily for 10 days.
  • For diabetic nerve pain, up to 3 grams of acetyl-L-carnitine or L-carnitine has been taken by mouth daily for up to one year. Carnitine has been injected into the muscle at a dosage of 1,000 milligrams daily for 10 days and taken by mouth at a dosage of 2,000 milligrams for 355 days.
  • For dialysis (CAPD), 1-1.6 grams of L-carnitine has been taken by mouth 1-2 times daily or before and after each session for up to one year. A dose of 1,500 milligrams or 10 milligrams per kilogram of L-carnitine has been taken by mouth after each session or three times weekly for up to 54 months, with lack of evidence of benefit. A dose of 2 grams of carnitine has been taken by mouth daily for 60 days. Carnitine or L-carnitine 10-40 milligrams per kilogram has been injected into the vein after sessions for up to six months. Doses of 2,100-14,000 milligrams of L-carnitine per week have been injected into the vein for up to 24 weeks.
  • For hemodialysis, 0.86-3 grams or 10 milligrams per kilogram of L-carnitine has been taken by mouth daily for 3-52 weeks. Doses of 0.5-2 grams or 5-25 milligrams per kilogram of L-carnitine have been injected into the vein for up to one year, three times weekly after sessions or after each session.
  • For nerve damage caused by antiretroviral treatment, acetyl-L-carnitine 500 milligrams has been taken by mouth twice daily during the first seven days, increased to 1,000 milligrams daily for days 8-14, then 1,500 milligrams twice daily for the remainder of 24 weeks, with unclear evidence of benefit.
  • For Down's syndrome, 10-30 milligrams per kilogram of acetyl-L-carnitine has been taken by mouth in three daily doses, with a lack of evidence of benefit.
  • For elimination of toxins, acetyl-L-carnitine 1,500 milligrams has been taken by mouth twice daily for up to 33 months.
  • For exercise performance, 1-6 grams of L-carnitine has been taken by mouth daily for up to 30 days, with lack of evidence of benefit. A dose of 2 grams of carnitine has been taken by mouth daily in two divided doses for six weeks. Supplement capsules containing 746 milligrams of carnitine (L-Carnipure®) have been taken by mouth up to twice daily during meals for up to 23 days. The following one-time doses have been taken by mouth: 2 grams of carnitine; 2-15 grams of carnitine dissolved in 200-250 milliliters of water, plus six drops of lemon juice or food; and 40 milligrams per kilogram of carnitine capsules. One gram of carnitine, dissolved in 20 milliliters of 0.9 percent saline, has been injected into the vein three times weekly for 12 weeks. A dose of 20 milligrams per kilogram of carnitine has been injected into the vein for eight weeks.
  • For fatigue, L-carnitine syrup 0.5 grams has been taken by mouth daily and increased over four days to 1 gram twice daily for 10 days. A dose of 1,000 milligrams of L-carnitine has been taken by mouth daily in two divided doses for one week, without evidence of benefit.
  • For fatigue (cancer), doses of 500-6,000 milligrams of carnitine have been taken by mouth daily for 1-4 weeks. Doses of 250-3,000 milligrams of L-carnitine have been taken by mouth twice daily for one week
  • For fatigue (celiac), 1 gram of L-carnitine has been taken by mouth twice daily for 180 days.
  • For fatty liver, 1-3 grams of carnitine has been taken by mouth for six months.
  • For fibromyalgia, two capsules of 500 milligrams of acetyl-L-carnitine taken by mouth plus one muscle injection of 500 milligrams of acetyl-L-carnitine have been taken daily for two weeks, and then three capsules of 500 milligrams of acetyl-L-carnitine have been taken by mouth daily for an additional eight weeks.
  • For fragile X syndrome, up to 50 milligrams per kilogram of acetyl-L-carnitine has been taken by mouth twice daily for one year.
  • For confused thinking due to liver disorders, 2 grams of L-carnitine or acetyl-L-carnitine has been taken by mouth twice daily for 60-90 days. Four grams of acetyl-L-carnitine has been injected into the vein in 500 milliliters of a 5 percent glycosylated solution over three hours, once daily for three days.
  • For liver inflammation, 2 grams of acetyl-L-carnitine has been taken by mouth twice daily for 12 months.
  • For HIV, 2 grams of acetyl-L-carnitine has been taken by mouth daily for eight months.
  • For high levels of lipids, 1-2 grams of L-carnitine has been taken by mouth daily for up to 12 weeks. A dose of 3 grams of L-carnitine has been taken by mouth daily for eight weeks.
  • For overactive thyroid, 2-4 grams of L-carnitine has been taken by mouth daily for 2-4 months.
  • For male infertility, 0.5-3 grams of carnitine, acetyl-L-carnitine, or propionyl-L-carnitine has been taken by mouth 1-3 times daily for up to six months. Combined L-carnitine and acetyl-L-carnitine have been taken by mouth for three months. L-carnitine 5 milliliters has been taken by mouth twice daily for three months.
  • For insulin sensitivity, 2 grams of acetyl-L-carnitine has been taken by mouth daily in two divided doses, in the morning and in the evening, for 24 weeks.
  • For leg ulcers, 2 grams of propionyl_L-carnitine has been taken by mouth twice daily for 12 weeks.
  • For liver disease, 600 milligrams of carnitine (Godex®) has been taken by mouth daily for three months.
  • For medium-chain acyl-CoA dehydrogenase deficiency (MCAD, 50 milligrams per kilogram of L-carnitine has been taken by mouth daily, with a lack of benefit.
  • For methadone withdrawal, 2 grams of acetyl-L-carnitine has been taken by mouth daily for three weeks.
  • For migraine, 500 milligrams of L-carnitine has been taken by mouth daily for 12 weeks.
  • For multiple sclerosis, 2 grams of acetyl-L-carnitine has been taken by mouth in two divded doses daily for three months. Doses of 1-2 grams of carnitine have been taken by mouth three times daily for six months.
  • For heart attack, 1.98 grams of L-carnitine has been taken by mouth daily for 28 days. Carnitine 9 grams has been injected into the vein daily for five days, followed by 4 grams of carnitine taken by mouth for six months. Five grams of L-carnitine have been injected into the vein for the first 36 hours, then 3 grams twice daily up to seven days. A dose of 100 milligrams per kilogram of L-carnitine has been injected into the vein every 12 hours for 36 hours.
  • For weight loss, 1.8 grams of L-carnitine has been taken by mouth daily for 30 days, with a lack of evidence of benefit. A dose of 15 milligrams per kilogram of carnitine has been taken by mouth daily for 26 weeks.
  • For peripheral neuropathy, 1 gram of L-carnitine has been taken by mouth daily for 15 days. A dose of 1,000 milligrams of acetyl-L-carnitine has been taken daily for the first 10 days, then taken by mouth at a dosage of 2,000 milligrams daily for a further 20 days. Acetyl-L-carnitine has been injected into the muscle for 14 days (1,000 milligrams daily), followed by 42 days of acetyl-L-carnitine 1,000 milligrams twice daily, with a lack of evidence of benefit. Acetyl-L-carnitine 1 gram has been taken by mouth three times daily for eight weeks. Two grams of carnitine have been injected into the vein three times weekly.
  • For peripheral neuropathy caused by chemotherapy, 1 gram of acetyl-L-carnitine has been injected into the vein twice daily as an infusion over 1-2 hours for 10 days.
  • For peripheral vascular disease, 1-4 grams of L-carnitine or propionyl-L-carnitine have been taken by mouth 1-2 times daily for up to 12 months. A dose of 250 milliliters of saline infusion containing 600 milligrams of propionyl-L-carnitine has been injected into the vein for three weeks, without evidence of benefit. Propionyl-L-carnitine has been injected into the vein in a continuous infusion, three times daily for the first 12 days, followed by an infusion every alternate day, six times, followed by treatment every three days, three times. Six grams of propionyl-L-carnitine has been injected into the vein for 12 hours daily for seven days. A dose of 300 milligrams of propionyl-L-carnitine in saline has been injected into the vein for 33 days, or 600 milligrams into the vein within 10 minutes of exercise for four weeks. Propionyl-L-carnitine therapy has been injected into the vein at a dosage of 1,200 milligrams for five days per week for four weeks. A dose of 600 milligrams of propionyl-L-carnitine has been injected into the vein in a 250 milliliter saline solution twice daily for 15 days.
  • For Peyronie's disease, 1 gram of propionyl-L-carnitine has been taken by mouth twice daily for six months, with a lack of evidence of benefit. Acetyl-L-carnitine 12 grams has been taken by mouth twice daily for three months.
  • For pregnancy (miscarriage), 3 grams of carnitine has been taken by mouth for one week, followed by 1 gram daily for another seven days.
  • For primary and secondary carnitine deficiency, 1-3 grams three times daily has been taken by mouth or injected into the vein.
  • For respiratory distress, 3 grams of L-carnitine has been taken by mouth daily for one week.
  • For Rett syndrome, 100 milligrams per kilogram of L-carnitine liquid has been taken by mouth daily in two doses for six months.
  • For sciatica, acetyl-L-carnitine 1,180 milligrams has been taken by mouth daily for 60 days, with a lack of evidence of benefit.
  • For sickle cell disease, 50 milligrams per kilogram of L-carnitine has been taken by mouth daily for six months, with evidence of benefit. Propionyl-L-carnitine 2 grams has been taken by mouth twice daily for 22 weeks, with a lack of evidence of benefit on leg ulcers.
  • For surgery, 1.8 grams of carnitine chloride has been taken by mouth daily for seven days. Five grams of L-carnitine has been injected into the vein as an infusion over two hours, twice daily for five days, and 10 grams of carnitine has been given through aortic root, without evidence of benefit. Doses of 3-6 grams of carnitine have been injected into the vein before undergoing heart surgery, without evidence of benefit. A dose of 0.05 grams per kilogram of L-carnitine has been injected into the vein in 250 milliliters of normal saline as a rapid infusion just before surgery.
  • For thalassemia, 50 milligrams per kilogram of L-carnitine has been taken by mouth daily for up to six months. A dose of 100 milligrams per kilogram of L-carnitine supplementation has been taken by mouth daily for one month.
  • For ulcerative colitis, 1-2 grams of propionyl-L-carnitine as sustained release tablets containing 0.5 grams of propionyl-L-carnitine hydrochloride have been taken by mouth daily (1-2 tablets twice daily) one hour before breakfast and one hour before dinner for four weeks.
  • For varicocele, 3 grams of carnitine has been taken by mouth three times daily for at least six months, with a lack of evidence of benefit.
  • For hair loss, a 2 percent carnitine solution has been applied to the scalp twice daily for six months.
  • For oily skin, a 2 percent L-carnitine formula has been applied to the skin for three weeks.
  • For cerebral ischemia, 1.5 grams of L-carnitine have been injected into the vein as a single dose. A dose of 3 grams of L-carnitine has been injected into the vein as a 14-day course drip, with lack of benefit.
  • For heart muscle injury due to carbon monoxide poisoning, 2 grams of L-carnitine has been injected into the vein daily for one week.

Children (under 18 years old)

  • For ADHD, 500-1,500 milligrams of acetyl-L-carnitine (depending on body weight) has been taken by mouth daily for 16 weeks, with a lack of evidence of benefit. Doses of 1,000-3,000 milligrams or 100 milligrams per kilogram of L-carnitine have been taken by mouth daily for 16-52 weeks.
  • For autism, 100 milligrams per kilogram daily of L-carnitine has been taken by mouth for 4-6 months.
  • For carnitine deficiency due to valproic acid use, 15 milligrams per kilogram of body weight of carnitine have been taken by mouth for one week.
  • For dialysis, 20-50 milligrams per kilogram of carnitine or L-carnitine has been taken by mouth daily for 2-3 months.
  • For high cholesterol, 3 grams of L-carnitine has been taken by mouth for up to six weeks.
  • For primary and secondary carnitine deficiency, 100-200 milligrams per kilogram of L-carnitine has been taken by mouth, divided over two or three doses, without exceeding 3 grams daily.
  • For Rett syndrome, 100 milligrams per kilogram of L-carnitine has been taken by mouth three times daily.
  • For tube feeding in babies, 50 micromoles per kilogram of L-carnitine has been given daily continuously through a feeding tube for seven days.
  • For premature babies, 130 milligrams per liter of L-carnitine (Carnitor®) has been injected into the vein at an infusion rate of 150 milliliters per kilogram. L-carnitine (Carnitor®) has been added to Pregestimil®, Nutramigen®, or Enfamil Premature® formulas or expressed human milk to provide 20 milligrams per kilogram of carnitine daily for eight weeks.
  • For respiratory distress, 30 milligrams per kilogram of L-carnitine has been injected into the vein until tube feeding of 120 milliliters per kilogram daily and then 30 milligrams per kilogram of carnitine taken by mouth daily were tolerated.
  • For total parenteral nutrition (TPN) in babies, 50 micromoles per kilogram of L-carnitine has been injected into the vein daily for two weeks. A dose of 10 milligrams per kilogram of carnitine (L-carn®) has been injected into the vein for nine days.

Safety

The U.S. Food and Drug Administration does not strictly regulate herbs and supplements. There is no guarantee of strength, purity or safety of products, and effects may vary. You should always read product labels. If you have a medical condition, or are taking other drugs, herbs, or supplements, you should speak with a qualified healthcare provider before starting a new therapy. Consult a healthcare provider immediately if you experience side effects.

Allergies

  • Avoid in people with known allergy or sensitivity to carnitine.

Side Effects and Warnings

  • Carnitine is likely safe when acetyl-L-carnitine is taken by mouth for one year at a dose of 2 grams daily.
  • Carnitine may cause aggression, anorexia, anxiety, back pain, blocked lung arteries, body odor, bronchitis, cellulitis, chronic lung disorders, colon inflammation, constipation, dandruff, decreased weight gain (low birth-weight babies), depression, diarrhea, difficulty sleeping, fatigue, feeling of well-being, fishy smell, fistula (an abnormal connection between organs), hair loss, headache, heart attack, heartburn, hernia (when an organ extends through the cavity that normally contains it), increased carnitine levels, increased triglyceride levels, infertility (women), inflammation of the pancreas, loose stools, mania, nausea, nervousness, pain or numbness in the neck and shoulder, pneumonia, psychosis, scalp burning or itching, sick sinus syndrome (heart rhythm disorders), skin rash, stomach discomfort or pain, tingling of the face, vomiting, and weakness.
  • Carnitine may affect blood pressure. Caution is advised in people who have high blood pressure or those taking drugs or herbs and supplements that lower blood pressure.
  • Carnitine may lower blood sugar levels. Caution is advised in people with diabetes or low blood sugar, and in those taking drugs, herbs, or supplements that affect blood sugar. Blood sugar levels may need to be monitored by a qualified healthcare professional, including a pharmacist, and medication adjustments may be necessary.
  • Carnitine may increase the risk of clotting. Caution is advised in people with bleeding disorders or taking drugs that increase the risk of bleeding, beta-blockers, or calcium channel blockers. Dosing adjustments may be necessary.
  • Carnitine may interfere with the way the body processes certain drugs using the liver's "cytochrome P450" enzyme system.
  • Use cautiously in people who have or are at risk of hepatitis C (long-term liver inflammation), liver scarring caused by alcohol, lung disorders, mental illness, peripheral vascular disease, sleeping disorders, or stomach or intestine disorders (such as irritable bowel syndrome or acid reflux disease), or those undergoing hemodialysis.
  • Use cautiously in women and in low-birth weight infants.
  • Avoid using D- or DL-carnitine. Avoid formulas that contain compounds similar to L-carnitine but deviate from the standard 99 percent similarity or greater.
  • Avoid in children and in pregnant or breastfeeding women.
  • Avoid in people with known allergy or sensitivity to carnitine.

Pregnancy and Breastfeeding

  • There is a lack of scientific evidence on the use of carnitine during pregnancy or breastfeeding. Avoid using in pregnant or breastfeeding women, due to a lack of safety information.

Interactions

Interactions with Drugs

  • Carnitine may increase the risk of clotting when taken with drugs that increase the risk of bleeding. Some examples include aspirin, anticoagulants ("blood thinners") such as warfarin (Coumadin®) or heparin, anti-platelet drugs such as clopidogrel (Plavix®), and non-steroidal anti-inflammatory drugs such as ibuprofen (Motrin®, Advil®) or naproxen (Naprosyn®, Aleve®).
  • Carnitine may lower blood sugar levels. Caution is advised when using medications that may also lower blood sugar. People taking drugs for diabetes by mouth or insulin should be monitored closely by a qualified healthcare professional, including a pharmacist. Medication adjustments may be necessary.
  • Carnitine may affect blood pressure. Caution is advised in people taking drugs that lower blood pressure.
  • Carnitine may interfere with the way the body processes certain drugs using the liver's "cytochrome P450" enzyme system. As a result, the levels of these drugs may be altered in the blood, and may cause altered effects or potentially serious adverse reactions. People using any medications should check the package insert, and speak with a qualified healthcare professional, including a pharmacist, about possible interactions.
  • Carnitine may also interact with 2,3-Dimercapto-1-propanesulfonic acid, 3,4-Methylenedioxymethamphetamine (MDMA or ecstasy), acetaminophen, acetylcholinesterase (AChE) inhibitors, adefovir dipivoxil, adriamycin, agents for blood vessel width, agents for the ears, agents for the eyes, agents for the heart, agents for heart rate regulation, agents for the immune system, agents for the lungs, agents for the nervous system, agents for osteoporosis, agents for promoting urine flow, agents for retrovirus infections (HIV), agents for the stomach, agents toxic to the kidneys or liver, alcohol, alpha-interferon, Alzheimer's agents, amiodarone, antibiotics, anticancer agents, antidepressants, anti-inflammatory agents, anti-seizure agents, aristolochic acid, azithromycin, beta blockers, bupivacaine, calcium channel blockers, carboplatin, cefepime, cephalosporins, cholesterol-lowering agents, cinnoxicam, cisplatin, clofibrate, cyclophosphamide, digoxin, doxorubicin, erythropoietin, exercise performance agents, fertility agents, fluoroquinolones, gentamicin, glycosides, hair agents, hydroxyurea, ifosamide, indomethacin, insulin preparations, interferon-alpha and -beta, interleukins, irradiation, isoretinoin, leupeptin, levamisole, levofloxacin, lymphoblastoid interferon-alpha, memory agents, methamphetamine, mildronate, mitoxantrone, natalizumab, nipecotic acid, nitro derivatives, nortriptyline, nucleoside analogs, OCTN2 inhibitors, opioid antagonists, orlistat, oxiplatin, paclitaxel, pain relievers, penicillins, phenazopyridine, phosphodiesterase inhibitors, pioglitazone, potassium chloride, progesterone, propafenone, propiconazole, radioactive agents, ribavirin, sildenafil, simvastatin, tacrolimus, tadalfil, tetradecylthioacetic acid (TTA), thyroid hormones, tilisolol, tilmicosin, triheptanoin, valproic acid, weight loss agents, wound-healing agents, zidovudine (AZT), and zwitterionic drugs (levofloxacin and grepafloxacin).

Interactions with Herbs and Dietary Supplements

  • Carnitine may increase the risk of clotting when taken with herbs and supplements that are believed to increase the risk of bleeding. Multiple cases of bleeding have been reported with the use of Ginkgo biloba, and fewer cases with garlic and saw palmetto. Numerous other agents may theoretically increase the risk of bleeding, although this has not been proven in most cases.
  • Carnitine may interfere with the way the body processes certain herbs or supplements using the liver's "cytochrome P450" enzyme system. As a result, the levels of other herbs or supplements may be altered in the blood. It may also alter the effects that other herbs or supplements possibly have on the P450 system.
  • Carnitine may lower blood sugar levels. Caution is advised when using herbs or supplements that may also lower blood sugar. Blood glucose levels may require monitoring, and doses may need adjustment.
  • Carnitine may affect blood pressure. Caution is advised in people taking herbs or supplements that lower blood pressure.
  • Carnitine may also interact with acupuncture, alpha-ketoglurate, alpha-lipoic acid, alpha-tocopherol, Alzheimer's herbs and supplements, antibacterials, anticancer herbs and supplements, antidepressants, anti-inflammatory herbs and supplements, antioxidants, anti-seizure herbs and supplements, antivirals, arginine, athletic performance enhancers, betaine, biotin, branched-chain amino acids, butyrate, caffeine, calcium, cholesterol-lowering herbs and supplements, choline, coenzyme Q10, conjugated linoleic acid (CLA), copper, fertility herbs and supplements, Garcinia cambogia, genistein, glycerophosphocholine, hair herbs and supplements, herbs and supplements for blood vessel width, herbs and supplements for the ears, herbs and supplements for the eyes, herbs and supplements for the heart, herbs and supplements for the immune system, herbs and supplements for the lungs, herbs and supplements for the nervous system, herbs and supplements for osteoporosis, herbs and supplements for promoting urine flow, herbs and supplements for the stomach and intestines, herbs and supplements toxic to the kidneys or liver, iron, licorice, lotus leaf extract, lysine, magnesium, medium-chain triglycerides, memory herbs and supplements, N-acetyl cysteine, nickel, nicotinamide, omega-3 fatty acids, pain relievers, phosphatidylserine, progesterone, S-adenosyl methionine, selenium, sesame lignans, silymarin, soy, Stevia rebaudiana Bertoni extract, St. John's wort, taurine, thyroid herbs and supplements, vitamin B12, vitamin C, weight loss herbs and supplements, wound-healing herbs and supplements, and Wuzi Yanzong liquids.

Attribution
  • This information is based on a systematic review of scientific literature edited and peer-reviewed by contributors to the Natural Standard Research Collaboration (www.naturalstandard.com).

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Copyright © 2011 Natural Standard (www.naturalstandard.com)


The information in this monograph is intended for informational purposes only, and is meant to help users better understand health concerns. Information is based on review of scientific research data, historical practice patterns, and clinical experience. This information should not be interpreted as specific medical advice. Users should consult with a qualified healthcare provider for specific questions regarding therapies, diagnosis and/or health conditions, prior to making therapeutic decisions.

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