Medically reviewed by Kristie Reed, PharmD Key Takeaways B12 shots work fast but don’t last long. Most leaves your body ...

Vitamin B12 is an essential vitamin, and low levels are linked to obesity. B12 shots could improve fatigue if you have a deficiency, but there’s not much research on them as a weight loss treatment.

Tirzepatide (Mounjaro®, Zepbound®) is a once-weekly diabetes and weight loss medication. Compounded tirzepatide is sometimes combined with vitamin B12 to provide additional health benefits. We’ll ...