Acetyl-L-Carnitine

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

In the body, acetyl-L-carnitine is made from L-carnitine. It can also be converted to L-carnitine. L-carnitine is an amino acid (a building block for proteins) that is naturally produced in the body. It helps produce energy. Although it is an amino acid, L-carnitine is not used to make proteins.

Acetyl-L-carnitine is used for a variety of mental disorders including Alzheimer's disease, age-related memory loss, late-life depression, thinking problems related to alcoholism, thinking problems related to Lyme disease, and thinking problems related to very poor liver function (hepatic encephalopathy). It is also used for withdrawal from alcohol, Down syndrome, bipolar disorder, poor circulation in the brain after a stroke, cataracts, nerve pain due to diabetes, nerve pain due to drugs used in the treatment of AIDS or cancer, nerve pain caused by sciatica, fibromyalgia, and facial paralysis. Acetyl-L-carnitine is used for tiredness related to getting older, tiredness related to a disease called multiple sclerosis, a muscle wasting disease called amyotrophic lateral sclerosis, high levels of activity in children with the genetic condition fragile-X syndrome, and attention deficit-hyperactivity disorder (ADHD). It is also used for aging skin.

Some men use acetyl-L-carnitine for infertility, symptoms of "male menopause" (low testosterone levels due to aging), and a disease of the penis called Peyronie's disease.

Acetyl-L-carnitine is given intravenously (by IV) for alcohol withdrawal, nerve pain caused by antiviral drugs used to treat HIV, dementia, and reduced blood flow in the brain.

Acetyl-L-carnitine is injected into the muscle for a pain condition called fibromyalgia as well as nerve pain that typically affects the hands and feet (peripheral neuropathy).

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.

Possibly Effective for...

• Improving memory problems in elderly people. Taking acetyl-L-carnitine improves memory and mental function in older people with some memory loss.
• Tiredness in older people. Taking acetyl-L-carnitine improves feelings of mental and physical tiredness in older people. It also appears to reduce feelings of tiredness after exercise.
• Age-related testosterone deficiency ("male menopause"). 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 withdrawal. 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.
• Treating Alzheimer's 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's disease. It is more likely to help those with early-onset Alzheimer's disease who are less than 66 years of age and have a faster rate of disease progression and mental decline.
• Poor blood flow to the brain. Administering a single dose of acetyl-L-carnitine intravenously (by IV) seems to produce short-term improvements in blood flow in the brains of people who have poor blood circulation in the brain.
• Improving memory in alcoholics. Taking acetyl-L-carnitine seems to improve memory in 30-60 year-old people whose use of alcohol has produced long-term thinking problems.
• Reducing nerve pain (neuropathy) caused by diabetes. 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 or who have poorly controlled type 2 diabetes. Also, doses of 1000 mg taken two or three times daily seems to work better than doses of 500 mg three times daily.
• Poor brain function in people with liver failure (hepatic encephalopathy). Taking acetyl-L-carnitine improves physical function and may improve mental function in people with poor brain function due to liver failure. It also might improve liver function, as indicated by reduced blood levels of ammonia.
• Treating male infertility. Taking acetyl-L-carnitine by mouth, along with L-carnitine, seems to increase sperm motion and may increase the rate of pregnancy in infertile men. Also, taking acetyl-L-carnitine and L carnitine after treatment with non-steroidal anti-inflammatory drugs (NSAIDs) seems to improve sperm count and sperm movement in men with infertility caused by a swelling of the prostate gland, seminal vesicles, and epididymis. In addition, taking a combination of acetyl-L-carnitine, L-carnitine, L-arginine, and Panax ginseng seems to increase sperm movement in men with infertility due to reduced sperm movement. It might also increase sperm movement and sperm count in men with infertility due to prostate swelling caused by Chlamydia infection.
• Treating Peyronie's disease, a connective tissue disease in men. Acetyl-L-carnitine seems to be more effective than a drug called tamoxifen for reducing pain and slowing worsening of the condition.

Possibly Ineffective for...

• Reducing nerve pain (neuropathy) caused by chemotherapy. 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 chemotherapy might be reduced by a small amount, even if the time the pain lasts is not reduced.

Insufficient Evidence to Rate Effectiveness for...

• Muscle wasting due to amyotrophic lateral sclerosis (ALS, Lou Gehrig's disease). Early research suggests 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.
• Reducing nerve pain (neuropathy) caused by HIV treatment. Early research suggests 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.
• Depression. Early research suggests that acetyl-L-carnitine might improve mood and decrease depression in elderly people.
• 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.
• A genetic condition called 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.
• Multiple sclerosis. Early research suggests that taking acetyl-L-carnitine might reduce feelings of tiredness in people with multiple sclerosis.
• Pain due to pressure on the sciatic nerve in the lower back (sciatica). Early research suggests that taking acetyl-L-carnitine reduces the need for pain medication in people with sciatica. However, it is not as effective as the supplement alpha-lipoic acid.
• Cataracts.
• Down syndrome.
• Thinking problems related to Lyme disease.
• Other conditions.

More evidence is needed to rate the effectiveness of acetyl-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).

Acetyl-L-carnitine is LIKELY SAFE for most adults and POSSIBLY SAFE for most children when taken by mouth. 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.

Acetyl-L-carnitine is POSSIBLY SAFE for most adults when given by another route than by mouth. Use only under medical supervision.

Pregnancy and breast-feeding: Not enough is known about the use of acetyl-L-carnitine during pregnancy and breast-feeding. Stay on the safe side and avoid use.

Nerve pain (neuropathy) caused by chemotherapy: Acetyl-L-carnitine might worsen symptoms in some people with nerve pain caused by a class of chemotherapy drugs known as taxanes.

Under-active 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.

---

Acenocoumarol (Sintrom)Interaction Rating: Major Do not take this combination.

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. This might increase the change of bruising and bleeding. The dose of your acenocoumarol (Sintrom) might need to be changed.

---

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

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.

The following doses have been studied in scientific research:

BY MOUTH:

• For age-related memory loss: 1500-2000 mg of acetyl-L-carnitine has been used daily for 3 months.
• For age-related tiredness: 2 grams of acetyl-L-carnitine has been used twice daily for 180 days.
• For age-related testosterone deficiency: 2 grams of acetyl-L-carnitine plus 2 grams of propionyl-L-carnitine has been used daily for 6 months.
• For alcohol withdrawal: 1-3 grams of acetyl-L-carnitine has been administered 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's 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 improving memory in people who use alcohol excessively: 2 grams of acetyl-L-carnitine has been used daily for 90 days.
• For nerve pain in people with diabetes: 1500-3000 mg of acetyl-L-carnitine has been taken by mouth daily in divided doses for 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 poor brain function in people with liver disease (hepatic encephalopathy): 2 grams of acetyl-L-carnitine has been taken twice daily for 90 days.
• For 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: 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 6 months along with 600 mg of prulifloxacin.
• For Peyronie's disease: 1 gram of acetyl-L-carnitine has been taken twice daily for 3 months.
BY IV:
• For alcohol withdrawal: 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.
• For improving blood flow to the brain: A single dose of 1500 mg of acetyl-L-carnitine has been given by IV.

AS A SHOT:

• For nerve pain caused by diabetes: 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.