What are the symptoms of vitamin B12 deficiency?

Vitamin B12 supports healthy red blood cells and the nervous system. Reduced levels may therefore produce tiredness, breathlessness on exertion or a pale appearance, alongside nerve symptoms such as pins and needles, reduced sensation or unsteadiness. Some people develop concentration or memory changes. Symptoms can build gradually and overlap with anaemia, thyroid problems, medication effects and other conditions, so symptoms alone cannot establish the cause.

Arrange a medical review if tiredness, weakness, altered sensation or cognitive changes persist. A blood test can assess vitamin B12 alongside related blood measures and help guide the next step. Tell the clinician about your diet, digestive symptoms, medicines and any supplements, because these details may affect interpretation and treatment.

Seek urgent help for sudden weakness, new trouble walking, severe dizziness, confusion, fainting or rapidly worsening numbness. Persistent nerve symptoms deserve timely assessment because untreated deficiency can affect nerve function.

Ask which blood tests are appropriate, whether another condition or medicine could explain the symptoms, whether supplements should be started before testing, and how progress will be monitored.