Ferrous sulfate with folic acid
Brand names: Ferrograd Folic, Slow-Fe Folic
This combination of ferrous sulfate with folic acid is used mainly for the prevention of iron and folate deficiency in pregnancy.
Adult dose
Dose independently re-sourced from UK Summary of Product Characteristics (SPC) via the eMC; US FDA prescribing information (openFDA / DailyMed) — cross-check; US labelling may differ from UK — clinician-reviewed. Always confirm against the product SmPC and your local formulary before prescribing.
Contraindications
- Megaloblastic anaemia due to primary vitamin B12 deficiency
- Pernicious anaemia
- Intestinal diverticular disease or any intestinal obstruction
- Haemochromatosis and haemosiderosis (iron preparations are contraindicated)
- Patients receiving repeated blood transfusions
- Concomitant use with parenteral iron therapy (oral iron preparations are contraindicated when used concomitantly)
- Hypersensitivity to folic acid (rare)
Side effects
- Nausea, vomiting, abdominal pain or discomfort, blackening of stools, diarrhoea and/or constipation — the side effects reported are similar to those of conventional oral iron preparations, but the incidence is less owing to the prolonged-release nature of the formulation
- Allergic reaction — isolated cases reported, ranging from rash to anaphylaxis; allergy is more common in people who are allergic to aspirin
- Allergic sensitisation has been reported following both oral and parenteral administration of folic acid
- Bronchial stenosis (see the aspiration warning in §4.4)
- Mouth ulceration (post-marketing, frequency not known) — in the context of incorrect administration, when the tablets are chewed, sucked or kept in the mouth
- Oesophageal lesions or bronchial necrosis in elderly patients and patients with deglutition disorders, in case of false route
Monitoring
- Exclude primary vitamin B12 deficiency and pernicious anaemia before starting — folic acid at the recommended dosage may obscure the neurological manifestations of pernicious anaemia
- Be aware that iron preparations colour the faeces black, which may interfere with tests used for the detection of occult blood in the stools; the guaiac test occasionally yields false positive results
- Evaluate the individual risk of aspiration in elderly patients and patients with swallowing difficulty before using iron sulfate tablets, and consider alternative formulations
- Advise patients to seek medical attention in case of suspected aspiration
- Consider the safety hazard of the controlled-release tablet and its inert plastic matrix in elderly or other patients with delayed intestinal transit
Clinical monograph
How it works
Ferrous sulfate supplies absorbable iron for haemoglobin synthesis, while folic acid provides the folate required for DNA synthesis and normal red cell maturation, together supporting erythropoiesis and neural tube development.
Prescribing in practice
- The folic acid dose in these prophylactic combinations is intended for prevention and is insufficient for established megaloblastic anaemia or for high-risk neural tube defect prophylaxis, which require dedicated higher-dose folic acid.
- Folic acid can mask the haematological signs of vitamin B12 deficiency while allowing neurological damage to progress, so exclude B12 deficiency before relying on folate alone.
- Standard iron absorption interactions apply, so separate from tea, antacids, calcium and chelated drugs such as tetracyclines and levothyroxine.
Monitoring
Monitor haemoglobin during pregnancy and review the formulation if treatment of an established anaemia rather than prophylaxis is required.
Counselling the patient
- This product is for preventing iron and folate deficiency, usually in pregnancy.
- Stools may turn black, which is harmless.
- Keep out of reach of children because of iron overdose risk.
Evidence & guidelines
NICE advises folic acid supplementation before and in early pregnancy to reduce neural tube defect risk, with combination iron-folate products used for routine antenatal prophylaxis.
Reference: NICE CG62; Confirm identity and dosing against the manufacturer SPC (eMC) and NICE. Verify against your local formulary and current prescribing references before prescribing. The structured dose values shown have been reviewed by a clinician. Monograph status: clinician-reviewed (2026-07-04).
Related
Curated clinical cross-links plus same-class fallbacks.
- Corrected Reticulocyte Count / Reticulocyte Production Index · Anaemia
- Ganzoni Equation for Iron Deficiency · Anaemia
- Transferrin Saturation Calculator · Anaemia / Iron Studies
- Tumor Lysis Syndrome (Cairo-Bishop Criteria) · Oncological Emergency
- Iron Deficiency Anaemia Calculator · Anaemia Assessment
- Ferritin Iron Store Interpretation · Haematological Values
- Major Haemorrhage / Massive Transfusion · BCSH; RCOA; RCEM; RCS — BCSH Guidelines
- Anaemia Investigation · BSH / NICE
- Splenomegaly Workup · BSH; BMJ Best Practice
- Deep Vein Thrombosis Diagnosis and Treatment · NICE CG144 / NICE NG158
- Sickle Cell Crisis · BSH 2021 / BCSH
- Neutropenic Sepsis · NICE CG151 2012 / ESMO