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.

Safety Safety definitions

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

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.