vitamin b12 injection /cyanocobalamin/1000 mcg/2 ml Cyanocobalamin 1000 mcg Multiple-Dose Vials — Mountainside Medical needles and syringes without needle (to use with any needle) are sold separately Cyanocobalamin B-12 Injection USP 1000mcg/mL

Common side effects (may affect up to 1 in 10 people): * Pain, redness, or swelling at the injection site * Nausea * Headache Uncommon side effects (may affect up to 1 in 100 people): * Diarrhea * Dizziness * Allergic reactions such as skin rash, itching, or hives Rare side effects (may affect up to 1 in 1,000 people): * Severe allergic reaction (anaphylaxis) with symptoms like difficulty breathing, swelling of the face or throat, and a drop in blood pressure

PMID 25738459

Its not completely known why this occurs, but its considered rare and shouldnt be a reason to put off getting the vaccine, explains Vino Palli, MD, founder of MiDoctor Urgent Care in New York City

Many report improved energy, reduced fatigue, better exercise capacity, and reduced carbohydrate cravings

The diagnostic criteria for Vit B12 deficiency followed standard clinical guidelines with levels below 200 pg/mL indicating its deficiency