Overview

In the body, acetyl-L-carnitine is made from L-carnitine. L-carnitine is a derivative of an amino acid. L-carnitine and acetyl-L-carnitine are used to help the body turn fat into energy.

People take acetyl-L-carnitine for improving memory and thinking skills, alcohol use disorder, bipolar disorder, nerve pain, fibromyalgia, infertility, and many other conditions, but there is no good scientific evidence to support these uses.

The body can convert L-carnitine to acetyl-L-carnitine and vice versa. But no one knows whether the effects of acetyl-L-carnitine are from the chemical itself, from the L-carnitine it can make, or from some other chemical made along the way. For now, don't substitute one form of carnitine for another.

How does it work ?

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

Uses & Effectiveness ?

Possibly Effective for

  • Decline in memory and thinking skills that occurs normally with age. Taking acetyl-L-carnitine improves memory and mental function in older people with some memory loss.
  • Tiredness in older adults. Taking acetyl-L-carnitine improves feelings of mental and physical tiredness in older people. It also appears to reduce feelings of tiredness after exercise.
  • Low levels of testosterone in older men. Taking acetyl-L-carnitine by mouth along with propionyl-L-carnitine seems to help symptoms related to declining male hormone levels. This combination taken for 6 months seems to improve sexual dysfunction, depression, and fatigue in much the same way the male hormone testosterone does.
  • Alcohol use disorder. When given intravenously (by IV) for 10 days then taken by mouth for 80 days, acetyl-L-carnitine helps reduce withdrawal symptoms and increase the amount of time before another alcoholic drink is consumed. However, most of the symptom improvement occurs during the first week. Therefore, it's not clear if taking acetyl-L-carnitine by mouth offers further benefit following IV treatment.
  • Alzheimer disease. Acetyl-L-carnitine might slow the rate of disease progression, improve memory, and improve some measures of mental function and behavior in some patients with Alzheimer disease. It is more likely to help those with early-onset Alzheimer disease who are less than 66 years of age and have a faster rate of disease progression and mental decline.
  • Decline in memory and thinking skills in older people that is more than what is normal for their age. Taking acetyl-L-carnitine seems to improve memory in 30-60 year-old people with long-term thinking problems due to alcohol use.
  • Depression. Taking 1-4 grams of acetyl-L-carnitine per day seems to improve mood and decrease depression in some people. It seems to work better in elderly people and when taken in higher amounts.
  • Nerve pain in people with diabetes (diabetic neuropathy). Taking acetyl-L-carnitine seems to improve symptoms in people with nerve pain caused by diabetes. Acetyl-L-carnitine seems to work best in people who have not had diabetes for a long time and those who have poorly controlled diabetes. Doses of 1000 mg taken two or three times daily seems to work better than smaller doses.
  • Conditions in a man that prevent him from getting a woman pregnant within a year of trying to conceive (male infertility). Taking acetyl-L-carnitine by mouth, usually along with L-carnitine and other supplements, seems to increase sperm count and sperm movement in men with fertility problems. Some research shows that this increases the chance of pregnancy.
  • A disease that causes curved, painful erections (Peyronie disease). Acetyl-L-carnitine seems to be more effective than a drug called tamoxifen for reducing pain and slowing worsening of Peyronie disease.

Possibly Ineffective for

  • Nerve damage in the hands and feet caused by cancer drug treatment. Acetyl-L-carnitine might not reduce neuropathy associated with chemotherapy in cancer patients. In fact, it might make it worse. But it's possible that severe nerve pain caused by a specific type of chemotherapy called sagopilone might be reduced by a small amount, even if the time the pain lasts is not reduced.

Insufficient Evidence for

  • Lou Gehrig's disease (amyotrophic lateral sclerosis or ALS). Early research shows that taking acetyl-L-carnitine along with the drug riluzole reduces the number of people with ALS who lose self-sufficiency compared to taking riluzole alone. It also seems to increase survival and improve physical function.
  • Nerve pain caused by drugs used to treat HIV/AIDS (antiretroviral toxic neuropathy). Early research shows that taking acetyl-L-carnitine by mouth might reduce nerve pain caused by antiretroviral treatment. However, acetyl-L-carnitine does not seem to work when injected into the muscle.
  • Attention deficit-hyperactivity disorder (ADHD). Taking acetyl-L-carnitine does not seem to improve symptoms of ADHD in children already treated with methylphenidate.
  • Bipolar disorder. Taking acetyl-L-carnitine plus alpha-lipoic acid for 12 weeks does not seem to improve symptoms of depression in people with bipolar disorder.
  • Carpal tunnel syndrome. Early research shows that taking acetyl-L-carnitine daily for 2 months does not help people regain function after having surgery for carpal tunnel syndrome.
  • Diabetes. Taking acetyl-L-carnitine does not seem to improve blood sugar or insulin levels in people with diabetes who are already taking medicine to lower blood sugar. It is unclear if acetyl-L-carnitine would benefit people with diabetes who are not taking diabetes medication.
  • Abnormal levels of cholesterol or blood fats (dyslipidemia). Taking acetyl-L-carnitine does not seem to improve cholesterol or other blood fats in people with dyslipidemia who are already taking drugs called "statins." It is unclear if acetyl-L-carnitine would lower cholesterol and blood fats in people not already taking statins.
  • Fibromyalgia. When injected into the muscle or taken by mouth, acetyl-L-carnitine appears to reduce some symptoms of fibromyalgia. The greatest benefit seems to be achieved when acetyl-L-carnitine is given using both routes.
  • An inherited condition marked by learning disabilities (fragile-X syndrome). Early research suggests that acetyl-L-carnitine does not improve mental function but might reduce hyperactive behavior in children with fragile X-syndrome.
  • Reduced brain function in people with advanced liver disease (hepatic encephalopathy). Early research shows that taking acetyl-L-carnitine does not improve symptoms in people with poor brain function due to liver failure.
  • High blood pressure. Taking acetyl-L-carnitine does not seem to lower blood pressure in people with high blood pressure who are already taking medicine for high blood pressure. It is unclear if acetyl-L-carnitine would lower blood pressure in people not taking medicine for high blood pressure.
  • Fatigue in people with multiple sclerosis (MS). Early research shows that taking acetyl-L-carnitine might reduce feelings of tiredness in people with MS.
  • Schizophrenia. Early research shows that taking acetyl-L-carnitine might reduce some symptoms of schizophrenia in people not well controlled with antipsychotic medicine. But acetyl-L-carnitine doesn't improve all symptoms. It also doesn't improve mental function.
  • Pain due to pressure on the sciatic nerve (sciatica). Early research shows that taking acetyl-L-carnitine reduces the need for pain medication in people with sciatica. But it is not as effective as the supplement alpha-lipoic acid.
  • Cataracts.
  • Down syndrome.
  • Other conditions.
More evidence is needed to rate the effectiveness of acetyl-L-carnitine for these uses.

Side Effects

When taken by mouth: Acetyl-L-carnitine is LIKELY SAFE for most people. It can cause some side effects including stomach upset, nausea, vomiting, dry mouth, headache, and restlessness. It can also cause a "fishy" odor of the urine, breath, and sweat.

When given by IV: Acetyl-L-carnitine is POSSIBLY SAFE for most adults when given intravenously (by IV). Use only under medical supervision.

Special Precautions and Warnings

Pregnancy and breast-feeding: There isn't enough reliable information to know if acetyl-L-carnitine is safe to use when pregnant or breast-feeding. Stay on the safe side and avoid use.

Children: Acetyl-L-carnitine is POSSIBLY SAFE for most children when taken by mouth.

Bipolar disorder: Acetyl-L-carnitine might worsen symptoms in people with bipolar disorder who are currently in remission.

Nerve damage in the hands and feet caused by cancer drug treatment: Acetyl-L-carnitine might worsen symptoms in some people with nerve pain caused by a class of chemotherapy drugs known as taxanes.

Underactive thyroid (hypothyroidism): There is some concern that acetyl-L-carnitine might interfere with thyroid hormone. Don't use acetyl-L-carnitine if you have an under-active thyroid.

Seizures: An increase in the number or seriousness of seizures has been reported in people with a history of seizures who have used L-carnitine by mouth or by IV (intravenously). Since L-carnitine is related to acetyl-L-carnitine, there is a concern that this might also occur with acetyl-L-carnitine. If you have ever had a seizure, don't take acetyl-L-carnitine.

Interactions ?

    Major Interaction

    Do not take this combination

  • Acenocoumarol (Sintrom) interacts with ACETYL-L-CARNITINE

    Acenocoumarol (Sintrom) is used to slow blood clotting. Acetyl-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.

    Moderate Interaction

    Be cautious with this combination

  • Warfarin (Coumadin) interacts with ACETYL-L-CARNITINE

    Warfarin (Coumadin) is used to slow blood clotting. Acetyl-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.

Dosing

The following doses have been studied in scientific research:

ADULTS

BY MOUTH:
  • For decline in memory and thinking skills that occurs normally with age: 1500-2000 mg of acetyl-L-carnitine has been used daily for 3 months.
  • For tiredness in older adults: 2 grams of acetyl-L-carnitine has been used twice daily for 180 days.
  • For low levels of testosterone in older men: 2 grams of acetyl-L-carnitine plus 2 grams of propionyl-L-carnitine has been used daily for 6 months.
  • For alcohol use disorder: 1-3 grams of acetyl-L-carnitine has been administered intravenously (by IV) for 10 days. Then for the next 80 days, 3 grams of acetyl-L-carnitine has been taken by mouth daily.
  • For Alzheimer disease: 1500-3000 mg of acetyl-L-carnitine has been taken by mouth daily in two or three divided doses for 3-12 months.
  • For decline in memory and thinking skills in older people that is more than what is normal for their age: 2 grams of acetyl-L-carnitine has been used daily for 90 days.
  • For depression: 1-4 grams of acetyl-L-carnitine has been used daily for up to 60 days. Higher doses seem to have the greatest effect.
  • For nerve pain in people with diabetes (diabetic neuropathy): 1500-3000 mg of acetyl-L-carnitine has been taken by mouth daily in divided doses for up to one year. In some cases, 1000 mg of acetyl-L-carnitine was injected into the muscles for 10-15 days before it was taken by mouth.
  • For conditions in a man that prevent him from getting a woman pregnant within a year of trying to conceive (male infertility):
    • 1 gram of acetyl-L-carnitine plus 2 grams of L-carnitine has been taken daily to treat male infertility
    • For male infertility secondary to abacterial prostatovesiculoepididymitis: 500 mg of acetyl-L-carnitine plus 1 gram of L-carnitine every 12 hours has been used following 2 months of treatment with nonsteroidal anti-inflammatory drugs (NSAIDs).
    • For male infertility due to low sperm movement: A combination containing 1660 mg of L-arginine, 150 mg of L-carnitine, 50 mg of acetyl-L-carnitine, and 200 mg of Panax ginseng has been taken daily for 3 months.
    • For male infertility due to prostate swelling caused by Chlamydia infection: combination containing 1660 mg of L-arginine, 150 mg of L-carnitine, 50 mg of acetyl-L-carnitine, and 200 mg of Panax ginseng daily for 6 months along with 600 mg of prulifloxacin.
    • For male infertility with low sperm numbers, low sperm movement, and abnormally shaped sperm (oligoasthenozoospermia): A specific product (Proxeed Plus, Alfasigma USA) containing L-carnitine 1 gram and acetyl-L-carnitine 0.5 gram, with citric acid, zinc, coenzyme Q10, selenium, vitamin C, folic acid, and vitamin B12, twice daily for 6 months.
  • For a disease that causes curved, painful erections (Peyronie disease): 1 gram of acetyl-L-carnitine has been taken twice daily for 3 months.
BY IV:
  • For alcohol use disorder: 1-3 grams of acetyl-L-carnitine has been given by IV over 3-4 hours for 10 days. Thereafter, 3 grams of acetyl-L-carnitine has been taken by mouth daily for 80 days.
AS A SHOT:
  • For nerve pain in people with diabetes (diabetic neuropathy): 1000 mg of acetyl-L-carnitine has been given as a shot daily for 10-15 days. In some cases, 2000 mg of acetyl-L-carnitine has been taken by mouth daily for 12 months following the shots.
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CONDITIONS OF USE AND IMPORTANT INFORMATION: This information is meant to supplement, not replace advice from your doctor or healthcare provider and is not meant to cover all possible uses, precautions, interactions or adverse effects. This information may not fit your specific health circumstances. Never delay or disregard seeking professional medical advice from your doctor or other qualified health care provider because of something you have read on WebMD. You should always speak with your doctor or health care professional before you start, stop, or change any prescribed part of your health care plan or treatment and to determine what course of therapy is right for you.

This copyrighted material is provided by Natural Medicines Comprehensive Database Consumer Version. Information from this source is evidence-based and objective, and without commercial influence. For professional medical information on natural medicines, see Natural Medicines Comprehensive Database Professional Version. © Therapeutic Research Faculty 2018.