Acetyl-l-carnitine
Acetyl-l-carnitine

Background

Acetyl-L-carnitine is made from L-carnitine in the body. L-carnitine and acetyl-L-carnitine are used to help the body turn fat into energy.

Acetyl-L-carnitine is important for many body processes. L-carnitine is made in the human brain, liver, and kidneys. The body can convert L-carnitine to acetyl-L-carnitine and vice versa. It's not clear if the effects of acetyl-L-carnitine are from the chemical itself, from the L-carnitine it can make, or from some other chemical.

Acetyl-L-carnitine is sometimes used for Alzheimer disease, improving memory and thinking skills, treating symptoms of depression, and reducing nerve pain in people with diabetes. It is used for many other conditions, but there is no good scientific evidence to support many of these uses.
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.

Special Precautions & 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: L-carnitine seems to make seizures more likely in people who have had seizures before. 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.

Effectiveness

NatMed Pro rates effectiveness based on scientific evidence according to the following scale: Effective, Likely Effective, Possibly Effective, Possibly Ineffective, Likely Ineffective, Ineffective, and Insufficient Evidence to Rate.
Likely effective Effectiveness definitions
Possibly effective Effectiveness definitions
  • Decline in memory and thinking skills that occurs normally with age. Taking acetyl-L-carnitine by mouth might improve memory and mental function in older people with some memory loss.
  • Tiredness in older adults. Taking acetyl-L-carnitine by mouth might improve mental and physical tiredness in older people. It also seems to reduce tiredness after exercise.
  • Alcohol use disorder. Acetyl-L-carnitine given intravenously (by IV) for 10 days and then taken by mouth for 80 days, helps reduce withdrawal symptoms and cravings during alcohol detox. But it's possible that the benefits are from IV acetyl-L-carnitine only.
  • Alzheimer disease. Taking acetyl-L-carnitine by mouth might slow the rate of disease progression, improve memory, and improve some measures of mental function and behavior in some people with Alzheimer disease.
  • Depression. Taking 1-4 grams of acetyl-L-carnitine by mouth daily seems to improve mood and decrease depression in some people. It seems to work better in older people and when taken in higher amounts.
  • Nerve pain in people with diabetes (diabetic neuropathy). Taking acetyl-L-carnitine by mouth 2-3 grams daily seems to improve symptoms in people with nerve pain caused by diabetes.
  • Conditions in a male that prevent a female partner from getting pregnant (male infertility). Taking acetyl-L-carnitine by mouth along with L-carnitine seems to increase sperm movement, and possibly sperm count, in males with fertility problems. It's not clear if taking acetyl-L-carnitine alone helps or if the chance of pregnancy is improved.
Likely ineffective Effectiveness definitions
Possibly ineffective Effectiveness definitions
  • Nerve damage in the hands and feet caused by cancer drug treatment. Taking acetyl-L-carnitine by mouth might not reduce neuropathy associated with chemotherapy in cancer patients. It might actually make it worse.
There is interest in using acetyl-L-carnitine for a number of other purposes, but there isn't enough reliable information to say whether it might be helpful.
Insufficient evidence Effectiveness definitions

Dosing & administration

Acetyl-L-carnitine has most often been used by adults in doses of 1.5-3 grams by mouth daily, for up to 33 months. Speak with a healthcare provider to find out what dose might be best for a specific condition.

Interactions with pharmaceuticals

Acenocoumarol (Sintrom)

Interaction Rating=Moderate Be cautious with this combination.

Acenocoumarol is used to slow blood clotting. Acetyl-L-carnitine might increase the effects of acenocoumarol and increase the chance of bruising and bleeding. Be sure to have your blood checked regularly. The dose of your acenocoumarol might need to be changed.

Serotonergic drugs

Interaction Rating=Moderate Be cautious with this combination.

Acetyl-l-carnitine might increase a brain chemical called serotonin. Some medications also have this effect. Taking acetyl-l-carnitine along with these medications might increase serotonin too much. This might cause serious side effects including heart problems, seizures, and vomiting.

Thyroid hormone

Interaction Rating=Moderate Be cautious with this combination.

Acetyl-L-carnitine might decrease how well thyroid hormone works in the body. Taking acetyl-L-carnitine with thyroid hormone might decrease the effectiveness of thyroid hormones.

Warfarin (Coumadin)

Interaction Rating=Moderate Be cautious with this combination.

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

Interactions with herbs & supplements

D-carnitine: D-carnitine might interfere with the way the body uses L-carnitine. Taking D-carnitine might cause L-carnitine levels to drop too low (L-carnitine deficiency. Since L-carnitine is needed to make acetyl-L-carnitine, this might also lead to acetyl-L-carnitine deficiency. Don't take D-carnitine with acetyl-L-carnitine.
Herbs and supplements with serotonergic properties: Acetyl-L-carnitine increases a brain chemical called serotonin. Taking it along with other supplements that have this effect might cause serious side effects, including heart problems, seizures, and vomiting. Examples of supplements with this effect include 5-HTP, black seed, L-tryptophan, SAMe, and St. John's wort.

Interactions with foods

There are no known interactions with foods.
Acetyl-L-Carnitine
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Acetyl-L-Carnitine
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This monograph was last reviewed on 17/10/2023 11:00:00 and last updated on 24/03/2022 04:17:59. Monographs are reviewed and/or updated multiple times per month and at least once per year.
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