Currently, there isn't enough evidence to know whether acetyl-L-carnitine helps improve fatigue associated with multiple sclerosis (MS) or not. More study is needed.

Acetyl-L-carnitine is a form of L-carnitine, an amino acid that is found in nearly all cells of the body. L-carnitine plays a critical role in the production of energy from long-chain fatty acids. In addition, it increases the activity of certain nerve cells in the central nervous system.

Fatigue is reported in up to 90% of people with multiple sclerosis. The cause of the fatigue isn't well understood. However, some types of MS-related fatigue may happen due to nighttime waking from bladder dysfunction, pain, depression or the effort it takes to perform daily duties.

As for treating fatigue with acetyl-L-carnitine, some studies have suggested that supplements could ease MS-related fatigue in people with low blood levels of L-carnitine.

A small study found that acetyl-L-carnitine works better than certain medications, such as amantadine, used to treat fatigue. But additional studies have had inconclusive results, showing a possible, but not statistically significant, benefit to acetyl-L-carnitine in MS-related fatigue.

Although acetyl-L-carnitine generally has few or mild side effects, it can interfere with blooding-thinning medications and other drugs. Therefore, have a discussion with your health care provider before taking acetyl-L-carnitine or any other dietary supplement.