L-CARNITINE: Overview, Uses, Side Effects, Precautions, Interactions, Dosing and Reviews (2024)

Overview

L-carnitine is a chemical that is made in the human brain, liver, and kidneys. It helps the body turn fat into energy.

L-carnitine is important for heart and brain function, muscle movement, and many other body processes. The body can convert L-carnitine to other chemicals called acetyl-L-carnitine and propionyl-L-carnitine. But it's not clear whether the benefits of these other carnitines are the same.

L-carnitine is used to increase L-carnitine levels in people whose natural level of L-carnitine is too low. Some people also use L-carnitine for conditions of the heart and blood vessels, serious kidney disease, and many other conditions, but there is no good scientific evidence to support these uses.

Uses & Effectiveness ?

Effective for

  • L-carnitine deficiency. Taking L-carnitine by mouth or by IV is effective for treating L-carnitine deficiency caused by certain genetic diseases or other disorders. It's approved by the FDA for this use. IV products can only be given by a healthcare provider.

Possibly Effective for

  • Chest pain (angina). Taking L-carnitine by mouth or by IV seems to improve exercise tolerance in people with chest pain. Taking L-carnitine along with standard treatment also seems to reduce chest pain and improve exercise ability in people with cardiac syndrome X. People with this condition have chest pain but not blocked arteries. IV products can only be given by a healthcare provider.
  • Heart failure and fluid build up in the body (congestive heart failure or CHF). Taking L-carnitine by mouth or by IV seems to improve symptoms and increase exercise ability in people with heart failure. IV products can only be given by a healthcare provider.
  • High levels of cholesterol or other fats (lipids) in the blood (hyperlipidemia). Taking L-carnitine by mouth or by IV can improve cholesterol and triglyceride levels by a small amount. IV products can only be given by a healthcare provider.
  • Kidney failure. The FDA has approved giving L-carnitine by IV, but not by mouth, for kidney failure. This can only be given by a healthcare provider.
  • Conditions in a male that prevent a female partner from getting pregnant (male infertility). Taking L-carnitine by mouth, alone or together with acetyl-L-carnitine, increases sperm count and sperm movement in males with fertility problems. Some research shows that this increases the chance of pregnancy.
  • Swelling (inflammation) of the heart (myocarditis). Some children who have had diphtheria can develop myocarditis. Taking DL-carnitine by mouth seems to reduce the risk of myocarditis and death in these children.
  • Toxic side effects caused by the drug valproic acid. Toxicity caused by valproic acid seems to be linked with L-carnitine deficiency. Taking L-carnitine by mouth or by IV can prevent liver toxicity from valproic acid. IV products can only be given by a healthcare provider.

There is interest in using L-carnitine for a number of other purposes, but there isn't enough reliable information to say whether it might be helpful.

Side Effects

When taken by mouth: L-carnitine is likely safe when taken for up to 12 months. It can cause side effects such as stomach upset, heartburn, diarrhea, and seizures. It can also cause the urine, breath, and sweat to have a "fishy" odor. Avoid using D-carnitine and DL-carnitine. These forms of carnitine might block the effects of L-carnitine and cause symptoms that resemble L-carnitine deficiency.

Special Precautions and Warnings

When taken by mouth: L-carnitine is likely safe when taken for up to 12 months. It can cause side effects such as stomach upset, heartburn, diarrhea, and seizures. It can also cause the urine, breath, and sweat to have a "fishy" odor. Avoid using D-carnitine and DL-carnitine. These forms of carnitine might block the effects of L-carnitine and cause symptoms that resemble L-carnitine deficiency. Pregnancy: There isn't enough reliable information to know if L-carnitine is safe to use when pregnant. Stay on the safe side and avoid use.

Breast-feeding: Taking L-carnitine is possibly safe when taken by mouth while breast-feeding in the amounts recommended by a healthcare provider. Small amounts of L-carnitine have been given to infants in breast milk and formula with no reported side effects. The effects of large amounts are unknown.

Children: L-carnitine is possibly safe when used appropriately by mouth, short-term. It has been used safely by mouth for up to 6 months.

Underactive thyroid (hypothyroidism): Taking L-carnitine might make symptoms of hypothyroidism worse.

Seizures: L-carnitine seems to make seizures more likely in people who have had seizures before. If you have had a seizure, don't take L-carnitine.

Interactions ?

    Moderate Interaction

    Be cautious with this combination

  • Acenocoumarol (Sintrom) interacts with L-CARNITINE

    Acenocoumarol is used to slow blood clotting. 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.

  • Thyroid hormone interacts with L-CARNITINE

    L-carnitine seems to decrease how well thyroid hormone works in the body. Taking L-carnitine with thyroid hormone might decrease the effectiveness of the thyroid hormone.

  • Warfarin (Coumadin) interacts with L-CARNITINE

    Warfarin is used to slow blood clotting. 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.

Dosing

L-carnitine has most often been used by adults in doses of 2 grams by mouth daily. In children, L-carnitine has most often been used in doses of 50-100 mg/kg by mouth daily, for up to one year. Speak with a healthcare provider to find out what dose might be best for a specific condition.

Next

  • Common Searches:
  • Alpha Lipoic Acid
  • Apple Cider Vinegar
  • Black Cohosh
  • Calcium
  • Chromium
  • Coenzyme Q - 10
  • DHEA
  • Flaxseed
  • Folic Acid
  • Ginko
  • Glucosamine
  • Melatonin
  • Niacin
  • Magnesium
  • Probiotics
  • Red Yeast Rice
  • St. John's Wort
  • Vitamin C
  • Vitamin D
  • Vitamin E

Show More Show Less

You Might Also Like

Myths and Facts about Hypertrophic Cardiomyopathy

Spotting the Signs of HCM

Medications for HCM

CONDITIONS OF USE AND IMPORTANT INFORMATION: This information is meant to supplement, not replace advice from your doctor or healthcare provider and is not meant to cover all possible uses, precautions, interactions or adverse effects. This information may not fit your specific health circ*mstances. Never delay or disregard seeking professional medical advice from your doctor or other qualified health care provider because of something you have read on WebMD. You should always speak with your doctor or health care professional before you start, stop, or change any prescribed part of your health care plan or treatment and to determine what course of therapy is right for you.

This copyrighted material is provided by Natural Medicines Comprehensive Database Consumer Version. Information from this source is evidence-based and objective, and without commercial influence. For professional medical information on natural medicines, see Natural Medicines Comprehensive Database Professional Version.
© Therapeutic Research Faculty 2020.

L-CARNITINE: Overview, Uses, Side Effects, Precautions, Interactions, Dosing and Reviews (2024)

FAQs

What are the precautions for L-carnitine? ›

It has been used safely by mouth for up to 6 months. Underactive thyroid (hypothyroidism): Taking L-carnitine might make symptoms of hypothyroidism worse. Seizures: L-carnitine seems to make seizures more likely in people who have had seizures before. If you have had a seizure, don't take L-carnitine.

What are the side effects of taking L-carnitine? ›

Carnitine does not have an established tolerable upper intake level. However, doses of approximately 3 g/day of carnitine supplements can cause nausea, vomiting, abdominal cramps, diarrhea, and a fishy body odor [10,11].

Is it bad to take L-carnitine everyday? ›

In one review of L-carnitine's safety, doses of approximately 2 g per day appeared to be safe for long-term use. However, there were some mild side effects, including heartburn and indigestion ( 33 ). However, L-carnitine supplements may raise your blood levels of trimethylamine-N-oxide (TMAO) over time.

Who shouldn't take acetyl-L-carnitine? ›

Children and pregnant and breastfeeding women should not use carnitine, because its safety is unknown. Interactions. Check with your doctor first if you're taking blood-thinning drugs. Carnitine may interact with drugs or supplements that lower blood sugar.

Is L-carnitine safe for kidneys? ›

Several types of research have demonstrated no adverse effects of LC supplementation under its recommended dosages on kidney health. However, several case studies conducted on individuals with focal segmental glomerulosclerosis reported a correlation between LC supplementation and renal dysfunctions.

What is carnitine required for? ›

Carnitine mediates the transport of medium/long-chain fatty acids across mitochondrial membranes, facilitating their oxidation with subsequent energy production; in addition, it facilitates the transport of intermediate toxic compounds out of the mitochondria preventing their accumulation.

Is L-carnitine good for your heart? ›

L-carnitine is an amino acid needed to transport fats into the mitochondria (the place in the cell where fats are turned into energy). Adequate energy production is essential for normal heart function. Several studies using L-carnitine showed an improvement in heart function and a reduction in symptoms of angina.

Is L-carnitine safe for liver? ›

Additionally, L-carnitine can reduce lipid accumulation in the liver, improve bile flow, and decrease the cholestatic burden on the liver [53]. Clinical studies: Several clinical studies have demonstrated the positive impact of L-carnitine on reducing GGT and ALP levels in patients with cholestasis.

How does L-carnitine affect the brain? ›

A derivative of L-carnitine, ALCAR easily crosses the blood brain barrier where it increases brain carnitine levels and helps increase acetylcholine, an important neurotransmitter vital to learning, memory, and general cognition (severe depletion of acetylcholine is associated with Alzheimer's disease).

What not to take with L-carnitine? ›

Warfarin (Coumadin) interacts with ACETYL-L-CARNITINE

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.

Does L-carnitine affect sleep? ›

l-carnitine treatment significantly improved the total time for dozing off during the daytime, calculated from the sleep logs, compared with that of placebo-treated periods. l-carnitine efficiently increased serum acylcarnitine levels, and reduced serum triglycerides concentration.

What happens if I stop taking L-carnitine? ›

While L-carnitine supplements are generally considered safe, abrupt discontinuation may lead to potential withdrawal effects such as fatigue, muscle cramps, and irritability.

Are there any negative effects of L-carnitine? ›

High doses (5 or more grams per day) may cause diarrhea. Other rare side effects include increased appetite, body odor, and rash. People with the following conditions should talk to their provider before taking carnitine: Peripheral vascular disease.

Does carnitine affect thyroid? ›

In particular, L-carnitine inhibits both triiodothyronine (T3) and thyroxine (T4) entry into the cell nuclei. This is relevant because thyroid hormone action is mainly mediated by specific nuclear receptors.

Is L-carnitine safe for high blood pressure? ›

Purpose: Hypertension stands as a prominent risk factor for cardiovascular disease, making it of utmost importance to address. Studies have shown that L-carnitine supplementation may lower blood pressure (BP) parameters in different populations.

How do you take L-carnitine for best results? ›

While as little as 1 gram of L-carnitine can be effective, your best bet is to take 2-3 grams per dose for maximum benefit, along with at least 30-40 grams of carbs and 20-40 grams of protein, preferably with a meal. This applies if you take straight-up L-carnitine, L-carnitine L-tartrate, or propionyl-L-carnitine.

Is L-carnitine linked to heart disease? ›

These bacteria digest L-carnitine and turn it into a compound called trimethylamine-N-oxide (TMAO). In studies in mice, TMAO has been shown to cause atherosclerosis, the disease process that leads to cholesterol-clogged arteries. We know that clogged coronary arteries can lead to heart attacks.

What is the best time of day to take L-carnitine? ›

Because L-carnitine can be absorbed quickly into the body, especially when it's consumed in liquid form, the best time to take is in the morning and/or prior to workouts. It is recommended that you take between 2-4g of L-carnitine per day, divided into two or three evenly split dosages.

Top Articles
Latest Posts
Article information

Author: Otha Schamberger

Last Updated:

Views: 6212

Rating: 4.4 / 5 (75 voted)

Reviews: 82% of readers found this page helpful

Author information

Name: Otha Schamberger

Birthday: 1999-08-15

Address: Suite 490 606 Hammes Ferry, Carterhaven, IL 62290

Phone: +8557035444877

Job: Forward IT Agent

Hobby: Fishing, Flying, Jewelry making, Digital arts, Sand art, Parkour, tabletop games

Introduction: My name is Otha Schamberger, I am a vast, good, healthy, cheerful, energetic, gorgeous, magnificent person who loves writing and wants to share my knowledge and understanding with you.