There is After having a B12 shot, a person should monitor for adverse symptoms and seek medical help if they experience: severe pain at the injection site mild diarrhea a swelling sensation in the body temporary itching of the skin In rare cases, a person may also be at risk of: anaphylaxis pulmonary edema congestive heart failure peripheral vascular thrombosis, which involves blood clots polycythemia vera, which is a type of blood cancer If anyone experiences difficulty breathing, hives, or swelling, they need emergency medical help
A 2024 meta-analysis in JCEM, Inositol for Polycystic Ovary Syndrome: Systematic Review and Meta-analysis , found selective metabolic benefits in some contexts, which does not validate MIC injections for universal weight loss
22 There are no clinical guidelines for the treatment of subclinical vitamin B 12 deficiency (asymptomatic patients with decreased levels of vitamin B 12 and elevated levels of homocysteine and/or methylmalonic acid)
Over-the-counter B12 supplements are widely available in the UK in various forms, including: Cyanocobalamin tablets the most common form in supplements Methylcobalamin sometimes marketed as more bioavailable, though evidence for superiority over standard oral tablets is limited Sublingual (under-the-tongue) preparations no proven advantage over standard oral tablets has been established Combination B-vitamin complexes Patients should be aware that most supplements are regulated as food products , not medicines, and quality can vary between brands
Vitamin B12 injections are primarily recommended for individuals who have a confirmed B12 deficiency or conditions that impair their ability to absorb B12 from food