Ferrous sulfate

How it works

It delivers elemental iron in the ferrous form, absorbed in the duodenum and used for haemoglobin synthesis and replenishment of body iron stores.

Prescribing in practice

• Iron preparations are a frequent cause of accidental poisoning fatalities in children, so safe storage out of reach is essential.
• Absorption is impaired by tea, antacids, calcium and proton pump inhibitors, and it chelates tetracyclines, quinolones, levothyroxine and bisphosphonates, so dosing should be separated.
• Constipation, nausea and abdominal discomfort are common and may be eased by taking with food, with alternate-day dosing an option to improve tolerability.

Monitoring

Check haemoglobin after a few weeks to confirm a response and continue treatment after normalisation to restore iron stores.

Counselling the patient

• Expect black stools, which are harmless.
• Keep tablets safely away from children due to overdose risk.
• Do not take at the same time as tea, milk or antacids.

Evidence & guidelines

NICE identifies oral ferrous sulfate as the first-line treatment for iron-deficiency anaemia in adults.