Safety of L-Carnitine

Sometimes called levocarnitine, L-carnitine is a type of amino acid, the substances that form proteins. Though often recommended by natural medical practitioners for the treatment of heart disease and the improvement of athletic performance, oral L-carnitine supplements pose a risk for side effects.

Types of Side Effects

• Possible side effects of L-carnitine include nausea, vomiting, stomach upset, heartburn and diarrhea, reports RxList. The supplements may also cause your urine, breath or sweat to take on a fish-like odor.

Features

• Though unpleasant, the side effects of L-carnitine are typically mild and pose no longer-term health threats, reports the University of Maryland Medical Center. Side effects are most common at high dosages, such as 5g or more per day.

Drug Interactions

• When combined with blood-thinning medications, like Warfarin (coumadin) or Sintrom (acenocoumarol), L-carnitine poses an increased risk for easy bruising or prolonged bleeding following an injury or illness, according to RxList. L-carnitine may decrease the effectiveness of thyroid hormone medications like Armour thyroid, which can cause patients with hypothyroidism to experience symptoms from the disease, such as fatigue.

Risks

• Although rare, some patients develop allergic reactions to L-carnitine, resulting in chest pain, shortness of breath, hives and swelling of the face or extremities, warns the Physicians' Desktop Reference.

Considerations

• Because its effects upon fetal development are unknown, avoid taking L-carnitine if you are pregnant. If you have a history of peripheral vascular disease, hypertension, cirrhosis, diabetes or liver disease, it may not be safe for you to take L-carnitine, cautions the University of Maryland Medical Center.