For adults prescribed iron tablets or capsules for anaemia or low iron stores.
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How to take it
- Take it on an empty stomach: 30 minutes before food, or 2 hours after.
- Swallow it whole with a glass of water. A glass of lemon water is also fine.
- Once a day is enough. Taking it two or three times a day does not add much iron and causes more side effects. Your doctor may advise one tablet on alternate days, which is absorbed just as well.
- If it upsets your stomach, take it with a little food. Some iron absorbed is better than none taken.
Keep a gap from these
| What | Gap |
|---|---|
| Tea, coffee, milk, curd, eggs | 2 hours |
| Calcium tablets and antacids | 2 hours |
| Thyroid tablet | 4 hours |
| Some antibiotics (ask the pharmacist) | 2 hours |
Long-term acidity medicines reduce iron absorption. Tell the doctor if you take one daily.
What to expect
- Black stools are normal and harmless while on iron. But black, sticky, foul-smelling stools with giddiness, or vomiting of blood, mean bleeding: go to a hospital.
- Constipation, loose motions or nausea can occur. Tell the doctor: a change of dose, timing or preparation usually solves it. Do not simply stop.
- Liquid iron stains teeth. Drink it through a straw and rinse the mouth.
How long
- Haemoglobin is checked after 2 to 4 weeks. It should rise by about 1 g/dL in the first 2 weeks.
- Continue for about 3 months after the haemoglobin is normal, to refill the body's iron stores. Stopping early is the commonest reason anaemia returns.
Tell the doctor if
- You cannot tolerate the tablets even with food
- Your haemoglobin has not risen after 4 weeks of regular tablets
- You feel more breathless, giddy or tired
Iron given into a vein is an option when tablets do not work or cannot be tolerated.
Keep iron away from children
A small number of adult iron tablets can kill a young child. Store them high up, in a closed container. If a child swallows any, go to a hospital with a children's emergency department at once.
Questions about this sheet? Call Caspian Healthcare reception on +91 89193 41154. A doctor is on duty at all hours for problems that are not critical. Caspian has no emergency department: in an emergency call 108.
Where this comes from
- British Society of Gastroenterology: guidelines for the management of iron deficiency anaemia in adults, 2021
- American Gastroenterological Association: clinical practice update on management of iron deficiency anaemia, 2024
- Stoffel and others: iron absorption from oral iron supplements given on consecutive versus alternate days, Lancet Haematology 2017
- NHS: how and when to take ferrous sulfate
Prepared by Caspian Healthcare from the sources above. Last reviewed October 2026. General information: your own doctor's written instructions come first.