L-Carnitine

• Overview
• Uses
• Side Effects
• Precautions
• Interactions
• Dosing

L-carnitine is an amino acid that is naturally produced in the body. L-carnitine helps the body turn fat into energy. The body can convert L-carnitine to other amino acids called acetyl-L-carnitine and propionyl-L-carnitine. But, no one knows whether the benefits of carnitines are interchangeable. Until more is known, don't substitute one form of carnitine for another.

L-carnitine supplements are taken by mouth to increase L-carnitine levels in people whose natural level of L-carnitine is too low because they have a genetic disorder, are taking certain drugs (such as valproic acid for seizures or certain antibiotics for tuberculosis), or because they are undergoing a medical procedure (hemodialysis for kidney disease) that uses up the body's L-carnitine. It is also used as a replacement supplement in strict vegetarians, dieters, and low-weight or premature infants.

L-carnitine is taken by mouth for conditions of the heart and blood vessels including heart-related chest pain, congestive heart failure (CHF), heart complications of a disease called diphtheria, heart attack, heart disease, leg pain caused by circulation problems (intermittent claudication), reduced circulation in the arms and legs due to narrowed blood vessels (peripheral vascular disease), irregular heartbeat, and high cholesterol.

Some people use L-carnitine by mouth for muscle disorders associated with certain AIDS medications, difficulty fathering a child (male infertility), a brain development disorder called Rett syndrome, anorexia, body weakness and wasting due to an illness, weight loss, chronic fatigue syndrome and fatigue associated with multiple sclerosis, celiac disease, cancer, aging, diabetes, metabolic syndrome, overactive thyroid, attention deficit-hyperactivity disorder (ADHD), autism, leg ulcers, Lyme disease, a blood disorder called beta-thalassemia, loss of brain function due to liver damage, hepatitis C, non-alcoholic liver disease, memory, migraine headache, to improve athletic performance and endurance in healthy people and people with a lung condition called chronic obstructive pulmonary disease (COPD). It is also taken by mouth for narcolepsy and for spinal muscle weakness in children.

L-carnitine us given intravenously (by IV) to increase L-carnitine levels in people whose natural level of L-carnitine is too low because they have a genetic disorder, are taking certain drugs (valproic acid for seizures), or because they are undergoing a medical procedure (hemodialysis for kidney disease) that uses up the body's L-carnitine. It is also given by IV to improve immune function in people with HIV/AIDS, and to people who have had a heart attack. It is also used as a supplement for people on a feeding tube, and in low-weight or premature infants with breathing problems.

L-carnitine is applied to the skin for acne and hair loss.

L-carnitine is also used in eye drops for dry eyes.

How does it work?

L-carnitine helps the body produce energy. It is important for heart and brain function, muscle movement, and many other body processes.

Effective for...

• L-carnitine deficiency. The FDA has approved the use of L-carnitine, either taken by mouth or given intravenously (by IV), for treating L-carnitine deficiency caused by certain genetic diseases or other disorders.

Possibly Effective for...

• Chest pain (angina). Taking L-carnitine by mouth or intravenously (by IV) seems to improve exercise tolerance in people with chest pain. Taking L-carnitine along with standard treatment also seems to reduce chest pain and improve exercise ability in people with cardiac syndrome X. People with this condition have chest pain but not blocked arteries.
• Heart failure. Taking L-carnitine by mouth or intravenously (by IV) seems to improve symptoms and increase exercise ability in people with heart failure. Taking a specific product containing L-carnitine and coenzyme Q10 (Carni Q-Gel, Tishcon Corporation, Westbury, NY) also appears to improve symptoms of heart failure.
• Serious kidney disease. People in the last stage of long-term, serious kidney disease need to undergo hemodialysis, which can lower L-carnitine levels. The US Food and Drug Administration (FDA) has approved giving L-carnitine intravenously (by IV) but not by mouth to treat and prevent L-carnitine deficiency in these patients. There is mixed evidence about the effects of L-carnitine in treating disorders caused by low carnitine levels in people with serious kidney disease undergoing hemodialysis. Taking L-carnitine by mouth or giving L-carnitine intravenously might improve markers of anemia and inflammation in people with this condition. But L-carnitine does not seem to improve quality of life, muscle cramping, low blood pressure, breathing function, or exercise performance.
• High thyroid hormone levels (hyperthyroidism). Taking L-carnitine seems to improve symptoms such as rapid or pounding heartbeat, nervousness, and weakness in people with high thyroid hormone levels.
• Male infertility. Most research shows that taking L-carnitine, alone or in combination with acetyl-L-carnitine, increases sperm count and sperm movement in men with fertility problems.
• Inflammation of the heart (myocarditis). Taking D,L-carnitine by mouth seems to reduce the risk of death from myocarditis.
• Preventing side effects caused by valproic acid (Depacon, Depakene, Depakote, VPA), a seizure medication. Toxicity caused by valproic acid seems to be linked with L-carnitine deficiency. Giving L-carnitine intravenously (by IV) can prevent severe liver toxicity in people who accidentally ingested or took too much valproic acid.

Insufficient Evidence to Rate Effectiveness for...

• Acne. Early research suggests that applying a product containing L-carnitine to the face twice daily for 8 weeks reduces acne and improves quality of life in people with acne.
• Age-related fatigue. Early research shows that taking L-carnitine daily for 30 days improves physical and mental fatigue, increase muscle mass, and decrease fat mass in elderly people.
• Hair loss (androgenic alopecia). Early research suggests that applying an L-carnitine solution twice daily for 6 months increases hair on the scalp in people with male or female pattern hair loss.
• Toxicity from tuberculosis drugs. Some drugs used to treat tuberculosis have been linked to liver damage. Early research suggests that taking L-carnitine by mouth along with these drugs for 4 weeks reduces the risk for liver damage.
• Athletic performance. Intense exercise has been linked to a decrease in L-carnitine blood levels. However, research on the use of L-carnitine for improving athletic performance is inconsistent. Some studies suggest that L-carnitine improves athletic performance and endurance. However, other research suggests L-carnitine provides no benefits.
• Attention deficit-hyperactivity disorder (ADHD). Research suggests that taking L-carnitine does not appear to reduce ADHD symptoms in most children.
• Autism. Early research suggests that taking L-carnitine by mouth daily for 3 months reduces the severity of autism in children according to some but not all scales.
• Irregular heartbeat (arrhythmia). Early research suggests that L-carnitine might reduce irregular heartbeat.
• Blood disorder called beta-thalassemia. Early research suggests that L-carnitine might reduce symptoms of a blood disorder called beta-thalassemia.
• Wasting syndrome (cachexia). Early research suggests that taking L-carnitine can increase body mass index (BMI) and improve lean body mass in people with cancer and wasting syndrome. Also, taking L-carnitine in combination with antioxidants and certain prescription drugs used to increase appetite seems to improve lean body mass better than taking the prescription drugs alone.
• Weakening heart muscle (cardiomyopathy). Early research suggests that L-carnitine improves heart function in adults or children with a weak heart muscle.
• Cancer-related fatigue. Some cancer patients have low blood levels of L-carnitine, which might reduce energy and lead to fatigue. Some early research suggests that taking L-carnitine might improve fatigue in advanced cancer patients. However, other research suggests that it has no benefit.
• Celiac disease-related fatigue. Some celiac disease patients have low blood levels of carnitine, which might reduce energy and lead to fatigue. Some research shows that taking L-carnitine reduces fatigue associated with celiac disease. However, L-carnitine does not seem to improve depression or quality of life.
• Chronic fatigue syndrome. Early research suggests that taking L-carnitine for 2 months can improve symptoms of fatigue.
• Lung disease (chronic obstructive pulmonary disease). Early research suggests that L-carnitine can improve exercise performance in people with chronic obstructive pulmonary disease (COPD).
• Clogged arteries (coronary artery disease). Early research suggests that taking L-carnitine before exercise does not improve endurance in people with clogged arteries.
• Diabetes. Although some research suggests that L-carnitine might improve blood sugar control in people with diabetes, most research shows that L-carnitine does not have this effect. However, L-carnitine might improve blood sugar control and decrease body weight in people with diabetes when taken along with certain weight loss medications. There is mixed evidence regarding the effects of L-carnitine on cholesterol levels in people with diabetes. Some research shows that L-carnitine can decrease cholesterol levels, but other research shows no benefit.
• Fatigue. Early research shows that taking L-carnitine daily for 8 days does not reduce fatigue in healthy people.
• Declining brain function related to liver disease. Early research shows that taking L-carnitine daily for 60-90 days reduces ammonia levels and improves brain function in people with declining brain function related to severe liver disease.
• Fatigue due to hepatitis. Early research shows that taking L-carnitine daily reduces fatigue in people with hepatitis C who are also being treated with medication.
• Hepatitis B. Research suggests that taking a specific vitamin complex containing L-carnitine (Godex, Celltrion Pharm, Seoul) together with the drug entecavir daily for 12 months improve liver function in people with hepatitis B. But it does not seem to affect the amount of hepatitis B virus in the blood.
• Hepatitis C. Taking L-carnitine with the medications interferon-alpha and ribavirin seems to improve the response to treatment in people with hepatitis C.
• High blood fats. Early research shows that taking L-carnitine daily can reduce total cholesterol, low-density lipoprotein (LDL or "bad") cholesterol, and triglycerides in children with high blood fat levels. Also, taking L-carnitine can reduce levels of lipoprotein(a), a possible risk factor for cardiovascular disease, in people with high levels of lipoprotein(a).
• High triglycerides. Early research suggests that L-carnitine does not reduce triglyceride levels in people with high triglyceride levels.
• Low birth weight. Some research suggests that giving premature infants L-carnitine by mouth or intravenously (by IV) can increase weight. However, other research suggests that it does not increase body weight in premature infants.
• Memory. Early research shows that taking L-carnitine daily for 3 days does not improve memory in young adult females.
• Metabolic syndrome. Early research suggests that L-carnitine given intravenously (by IV) daily for 7 days increases weight loss and reduces waist circumference in people with metabolic syndrome. But it does not seem to affect blood pressure in people with this condition.
• Migraine headache. Early research suggests that taking L-carnitine daily, with or without magnesium oxide for 12 weeks, does not reduce migraines.
• Multiple sclerosis-related fatigue. Some people with multiple sclerosis have low blood levels of L-carnitine, which might cause low energy and fatigue. Early research shows that taking L-carnitine daily decreases some aspects of fatigue in people with multiple sclerosis who also have low L-carnitine levels.
• Heart attack. There is inconsistent evidence about the effects of using of L-carnitine after a heart attack. Some research suggests that taking L-carnitine by mouth after a heart attack improves heart function and reduces the risk of death. However, other studies suggest that it provides no benefit.
• Excessive daytime sleepiness (narcolepsy). Early research suggests that taking L-carnitine in the morning and evening for 8 weeks reduces dozing off during the day in people with narcolepsy. But it does not seem to affect the number of naps needed, quality of life, or sleepiness.
• Breathing problems while sleeping in infants. Early research suggests that adding L-carnitine to intravenous (IV) nutrition does not reduce breathing problems while sleeping in infants.
• Nonalcoholic liver disease (nonalcoholic steatohepatitis, NASH). Early research suggests that L-carnitine improves some aspects of liver function in people with liver disease not related to drinking alcohol.
• Blocked blood vessels not in the heart or brain. Some early research suggests that L-carnitine might improve walking in people with blocked blood vessels not in the heart or brain. However, other research suggests that it does not provide any benefits.
• A rare inherited disorder that affects the nervous system (Rett syndrome). Taking L-carnitine might improve well-being and movement in girls with Rett syndrome.
• Weight loss. Taking L-carnitine by itself does not appear to reduce body weight in overweight or obese people. However, taking L-carnitine with certain weight loss medications or supplements appears to reduce body weight and body mass index better than taking the weight loss medications or supplements alone.
• Eating disorders.
• Leg ulcers.
• Lyme disease.
• Spinal muscle loss.
• Other conditions.

More evidence is needed to rate L-carnitine for these uses.

Natural Medicines Comprehensive Database rates effectiveness based on scientific evidence according to the following scale: Effective, Likely Effective, Possibly Effective, Possibly Ineffective, Likely Ineffective, and Insufficient Evidence to Rate (detailed description of each of the ratings).

L-carnitine is LIKELY SAFE when taken by mouth for up to 12 months, and when used as an injection, with the approval of a healthcare provider. It can cause side effects such as nausea, vomiting, stomach upset, heartburn, diarrhea, and seizures. It can also cause the urine, breath, and sweat to have a "fishy" odor. Avoid using D-carnitine and DL-carnitine. These forms of carnitine might block the effects of L-carnitine and cause symptoms that resemble L-carnitine deficiency.

Pregnancy and breast-feeding: There is not enough reliable information about the safety of using L-carnitine if you are pregnant. Stay on the safe side and avoid use.

Taking L-carnitine is POSSIBLY SAFE in breast-feeding women when taken by mouth in the amounts recommended. Small amounts of L-carnitine have been given to infants in breast milk and formula with no reported side effects. The effects of large amounts taken by a breast-feeding mother are unknown.

Children: L-carnitine is POSSIBLY SAFE when used appropriately by mouth or intravenously (by IV), short-term. It has been used safely by mouth for up to 6 months.

Under-active thyroid (hypothyroidism): Taking L-carnitine might make symptoms of hypothyroidism worse.

Kidney failure: Using DL-carnitine has been reported to cause symptoms such as muscle weakness and eye drooping when administered intravenously (by IV) after dialysis. L-carnitine does not seem have this effect.

Seizures: L-carnitine seems to make seizures more likely in people who have had seizures before. If you have had a seizure, do not use L-carnitine.

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Acenocoumarol (Sintrom)Interaction Rating: Moderate Be cautious with this combination.Talk with your health provider.

Acenocoumarol (Sintrom) is used to slow blood clotting. L-carnitine might increase the effectiveness of acenocoumarol (Sintrom). Increasing the effectiveness of acenocoumarol (Sintrom) might slow blood clotting too much. The dose of your acenocoumarol (Sintrom) might need to be changed.

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Thyroid hormoneInteraction Rating: Moderate Be cautious with this combination.Talk with your health provider.

L-carnitine seems to decrease how well thyroid hormone works in the body. Taking L-carnitine with thyroid hormone might decrease the effectiveness of the thyroid hormone.

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Warfarin (Coumadin)Interaction Rating: Moderate Be cautious with this combination.Talk with your health provider.

Warfarin (Coumadin) is used to slow blood clotting. L-carnitine might increase the effects of warfarin (Coumadin) and increase the chances of bruising and bleeding. Be sure to have your blood checked regularly. The dose of your warfarin (Coumadin) might need to be changed.

The following doses have been studied in scientific research:

BY MOUTH:

• For L-carnitine deficiencies: 990 mg two to three times daily in tablets or as an oral solution.
• For chest pain (angina): Doses of 900 mg to 2 grams of L-carnitine have been taken in one to two divided doses daily for 2 weeks to 6 months.
• For heart failure: 1.5 to 3.0 grams of L-carnitine has been taken in one to two divided doses daily for up to about 34 months. A specific product (Carni Q-Gel, Tishcon Corporation,Westbury, NY) containing 2250 mg of carnitine and 270 mg of coenzyme Q10 has been taken daily for 12 weeks.
• For people with serious kidney disease undergoing hemodialysis: Doses of 0.64-3 grams or 10 mg/kg of L-carnitine has been used daily for 3-52 weeks. Taking L-carnitine by mouth is not FDA approved to treat carnitine deficiency in people with serious kidney disease.
• For high thyroid hormone levels (hyperthyroidism): 2-4 grams of L-carnitine has been taken daily for 2-4 months.
• For male infertility: 2-3 grams of L-carnitine has been taken in up to three divided doses daily, with or without vitamin E, for 2 to 24 weeks. Also, 2 grams of L-carnitine plus 1 gram of acetyl-L-carnitine has been taken daily, with or without a 300 mg cinnoxicam suppository every 4 days, for 3-6 months.
• For inflammation of the heart (myocarditis): 100 mg/kg of D,L-carnitine has been taken daily for 4 days.
• For preventing side effects caused by valproic acid (Depacon, Depakene, Depakote, VPA): 50 to 100 mg/kg has been taken in three or four divided doses daily up to a maximum of 3 grams daily.

BY IV:

• For chest pain (angina): An infusion of 3 grams of L-carnitine in 500 mL of 5% dextrose has been given once daily for 14 days. 40mg/kg of D,L-carnitine has also been given by IV 30 minutes before exercise.
• For L-carnitine deficiencies: Doses of 50 mg/kg of L-carnitine have been given as a slow injection or by infusion followed by 50 mg/kg of L-carnitine in divided doses every 3 to 4 hours over the next 24 hours. In the following days, daily maintenance doses are usually in the range of 50 mg/kg. For people with L-carnitine deficiency related to hemodialysis, 10 to 20 mg/kg of L-carnitine adjusted for L-carnitine blood levels is used.
• For heart failure: 5 grams of L-carnitine has been given by IV daily for 7 days in addition to conventional treatment.
• For serious kidney disease: Doses of 10 to 20 mg/kg of L-carnitine given as a slow injection is FDA-approved for use for L-carnitine deficiency in people with serious kidney disease. For treating disorders related to low levels of carnitine in hemodialysis patients, 1.8 grams of L-carnitine weekly to 3 grams daily or 30-120 mg/kg/week have been given by IV for 2 weeks to 12 months. Doses were usually given three times weekly after dialysis sessions. Also, 1 gram of L-carnitine has been given by IV three times weekly after each dialysis session together with 100 mg of coenzyme Q10 taken by mouth daily for 3 months.
• For preventing side effects caused by valproic acid (Depacon, Depakene, Depakote, VPA): 150-500 mg/kg has been taken daily. A maximum of 3 grams daily.