walgreens b12 injection Cyanocobalamin Vitamin 1000 mcg — Mountainside Medical B12 Intramuscular Injection

The regulatory landscape governing compounded medications is subject to change

Many commercial preparations contain additional ingredients such as: Sorbitol or mannitol sugar alcohols used as sweeteners in some tablets that can cause osmotic diarrhoea when consumed in larger quantities, though the amounts in typical supplements are usually too small to cause symptoms alone [13] [14] Binding agents and fillers including lactose, which may cause symptoms in people with lactose intolerance, though tablet quantities are typically small Other additives various excipients that some individuals may be sensitive to The dose and frequency of supplementation may also influence tolerability

You might consider a B12 shot if you follow a vegetarian or vegan diet, since B12 comes mainly from animal foods

There's no established upper limit for B12, and toxicity is extremely rare