Vitamin B12 deficiency can be caused by poor diet or malabsorption, leading to fatigue, muscle weakness, and memory problems.

Vitamin B12 is an essential nutrient that's often overlooked. Also known as cobalamin, vitamin B12 helps your body produce vital red blood cells and boost your energy levels, among other things.

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.

After receiving an injection, some people experience symptoms at the injection site on the skin. This reaction is a common adverse effect of vaccines, Botox injections, biologics, and chemotherapy.