Great Ormond Street lists the thigh, abdomen and buttock area among the most suitable sites for the same reason

You're a strong candidate for B12 injections if you experience any of the following: Persistent fatigue that sleep doesn't fix Brain fog, forgetfulness, or trouble concentrating Low mood, anxiety, or stress that feels disproportionate to what's happening Weight gain or difficulty losing weight despite consistent effort Tingling, numbness, or weakness in hands or feet (signs of B12-related neuropathy) Frequent colds, slow healing, or post-COVID fatigue A plant-based, vegetarian, or vegan diet Age 50 or older (B12 absorption naturally declines with age) A history of gastric bypass, Crohn's disease, celiac disease, or chronic acid reflux Long-term use of metformin (for diabetes), proton pump inhibitors (Prilosec, Nexium), or H2 blockers (Pepcid, Zantac) An MTHFR gene variant or known methylation issue A history of B12 deficiency, pernicious anemia, or low folate Hormonal shifts: perimenopause, menopause, postpartum If you fit one or more of these, a vitamin B12 shot is one of the lowest-risk, fastest-acting interventions available

Bacteriostatic Water Use 3.0 mL per vial for reconstitution
This step helps to minimize the risk of infection and ensure a smooth injection process
In conclusion, the length that B12 injection benefits last depends on many things, such as the type of injection, your overall health, and how you live your life
With 300 servings in a single bottle, it can last a single person 10 months, even if taken daily