The U.S. Food and Drug Administration (FDA) recommends 1 gram of L-carnitine three times per day, intravenously (injected), for primary and secondary carnitine deficiency; this dose should not exceed 3 grams per day. A variety of doses have been used, with 3 grams per day in divided doses for 2-4 months being the most common; however, the doses range from 1 to 9 grams per day. Conditions treated have included AIDS, memory in alcoholics, Alzheimer's disease, angina (chest pain), congestive heart failure, depression, diabetes, diabetic neuropathy, dialysis, exercise performance, hepatic encephalopathy (brain disease), hyperlipidemia (high cholesterol), hyperthyroidism, myocardial infarction (heart attack), peripheral neuropathy (nerve damage), and peripheral vascular disease.
Intravenous (needle into a vein) injections have also been used, with doses typically ranging from 15-50 milligrams per kilogram twice daily. Injections have been given for seven days up to one year. Higher doses (up to 9 grams per day) have been studied. Injections should only be given under the supervision of a qualified healthcare professional.
The U.S. Food and Drug Administration (FDA) does not recommend exceeding 3 grams carnitine daily for primary and secondary carnitine deficiency. A typical dose for these deficiencies, as well as Rett's syndrome, is 100-200 milligrams per kilogram taken daily divided over two or three doses. For hyperlipidemia (high cholesterol), 3 grams L-carnitine for up to six weeks has been used. For total parental nutrition in infants, 50 micromoles per kilogram for two weeks has been used. Injections should only be given under the supervision of a qualified healthcare professional.
Avoid in individuals with a known allergy or hypersensitivity to carnitine.
In general, L-carnitine is safe and no significant complications have been reported in available human clinical studies. Minor adverse effects have been reported with the use of L-carnitine or acetyl-L-carnitine, such as skin rash, body odor, "fishy smell," diarrhea, gastric pyrosis (heartburn), nausea, gastralgia (stomachache), loose bowel movement, nonspecific abdominal discomfort, or vomiting. Euphoria, insomnia, nervousness, mania, depression, and aggression have also been reported, but primarily in patients with pre-existing psychiatric conditions.
Transient hair loss was reported in 1% of cases. Less birth weight was regained in low birth weight infants treated with L-carnitine.
Carnitine supplements should be used cautiously in patients with peripheral vascular disease, hypertension (high blood pressure), alcohol-induced liver cirrhosis, low birth weight (infants), diabetics, and patients on hemodialysis.
L-carnitine is not recommended in pregnant or breastfeeding women due to a lack of available scientific evidence.