Iron deficiency anaemia means the blood is low in red cells because the body is short of iron. In men, and in women after menopause, the most common reason is slow, unseen blood loss from the gut. That is why iron deficiency in these groups should be investigated rather than only treated with iron tablets.
Common causes
- Bleeding from the stomach or bowel: ulcers, inflammation, polyps, angiodysplasia (fragile blood vessels) and bowel or stomach cancer
- Anti-inflammatory painkillers (NSAIDs) and aspirin
- Poor absorption of iron: coeliac disease, H. pylori, previous stomach surgery
- Heavy periods, in women before menopause
- Low dietary iron, which is rarely the only cause in adults
Investigations
For men and for women after menopause, guidelines advise both a gastroscopy and a colonoscopy, usually done in one session, together with a blood test for coeliac disease. Women before menopause may also need these tests, especially with gut symptoms, a family history of bowel cancer, or anaemia that returns despite treatment. If both scopes are normal, the small bowel may need to be examined, for example with capsule endoscopy.
Treatment
- Treat the cause that is found
- Iron tablets, often once a day or on alternate days, which can be easier on the stomach
- Iron given through a drip (intravenous iron) when tablets are not tolerated, not absorbed, or not enough
- A repeat blood test to confirm that the blood count and iron stores have recovered
General information only. Reviewed by Dr Chia Chung King, 2026-11-07. Book a consultation.