Levocarnitine Liv Hospital L Carnitine Injection vs. Oral Supplements: Which is More Effective? Katalyst Wellness Pharmacokinetics of L Carnitine Clinical Pharmacokinetics Springer Nature Link L carnitine is effective for both fat loss and athletic performance. However, oral L carnitine has lower bioavailability and can be harmful at high doses, so it should be avoided. , Even cardiologists