L Carnitine Benefits, Uses, Dosage, Foods, Side Effects Dr. Axe Benefits of Combining Supplements: L Carnitine & Methyl B 12: The Center for Internal and Integrative Medicine: Integrative Medicine Doctors Compounded Carnitine (L) Injection Empower Pharmacy L Carnitine injection is recommended at 1 ampule every 2 3 days for best results. The L Carnitine is taken intravenously either by normal injection or using a butterfly needle. After taking this L Carnitine, you GLP 1 with L Carnitine, B12, and B6 Reduce Nausea and Fatigue