What to expect from a vitamin B12 injection for vitamin B12 deficiency

The injection delivers vitamin B12 into the body without relying only on absorption through the gut. The schedule depends on the reason for deficiency, how low your levels are, and whether absorption is affected. Tiredness or mouth and tongue changes may improve before nerve symptoms; tingling, balance problems, or memory changes need careful follow-up.

Keep appointments even if you feel better, because restoring body stores may require an ongoing plan. Mild soreness, redness, or bruising at the injection site can occur. Tell your clinician about all medicines and supplements, and report new symptoms rather than changing the schedule yourself.

Seek urgent help for trouble breathing, swelling of the face or throat, widespread hives, severe dizziness, or collapse after an injection. Contact your clinician if the site becomes increasingly painful, hot, swollen, or produces discharge.

Ask what caused the deficiency, how often injections are needed, and which symptoms should improve first. Clarify when blood tests are planned, whether dietary changes are relevant, and whether treatment is likely to continue long term.