What should you know about a B12 shot?

Vitamin B12 supports healthy blood cells and normal nerve function. An injection may be considered for confirmed deficiency, poor absorption, or a condition affecting the stomach or bowel. A clinician may use a blood test to check B12 levels and investigate anaemia or another cause of symptoms. Fatigue, generalised weakness, and numbness or tingling can occur with deficiency, but they have many possible causes.

Tell the clinician about medicines, allergies, previous reactions to injections, pregnancy, and any known kidney or liver condition. Ask which B12 preparation and schedule are planned. The injection is usually given into a muscle, and the site may feel tender briefly. Keep appointments if repeat doses are advised, and do not add high-dose supplements without checking first. Improvement in blood-related symptoms may take time; nerve symptoms can require prompt assessment because delayed treatment may allow nerve problems to persist.

Seek urgent help for trouble breathing, swelling of the face or throat, faintness, or a widespread rash after an injection. Arrange medical review for worsening weakness, new difficulty walking, confusion, chest discomfort, or numbness that is spreading. Ongoing symptoms despite treatment deserve reassessment rather than extra injections on your own.

Ask what caused the suspected deficiency, whether a blood test is needed before treatment, how many injections are expected, and how response will be checked.