Vitamins and Haematinics
Pregnancy: Safe in pregnancy; essential for neural tube development
Folic Acid
Brand names: Lexpec
Adult dose
Dose: 5 mg
Route: Oral
Frequency: Once daily
Max: 15 mg/day (haemolytic anaemia)
Neural tube defect prevention: 400 micrograms daily pre-conception; high risk (prior NTD): 5 mg daily
Paediatric dose
Dose: 100-500 micrograms/kg (haemolytic anaemia) micrograms/kg
Route: Oral
Frequency: Once daily
Max: 5 mg/day
Megaloblastic anaemia: 100-500 micrograms/kg once daily. Haemolytic anaemia (e.g. sickle cell, thalassaemia): 2.5-5 mg daily. Neural tube defect prevention in mothers with prior NTD-affected child: 5 mg daily from pre-conception
Dose adjustments
Renal
No dose adjustment required
Hepatic
No dose adjustment required
Paediatric weight-based calculator
Megaloblastic anaemia: 100-500 micrograms/kg once daily. Haemolytic anaemia (e.g. sickle cell, thalassaemia): 2.5-5 mg daily. Neural tube defect prevention in mothers with prior NTD-affected child: 5 mg daily from pre-conception
Clinical pearls
- Always exclude vitamin B12 deficiency before starting folic acid alone — treating pernicious anaemia with folic acid alone can precipitate subacute combined degeneration of the spinal cord
- Sickle cell and thalassaemia patients: supplementation ongoing due to chronic haemolysis and increased folate demand
- Women of childbearing age with epilepsy on valproate or carbamazepine should take 5 mg/day — enzyme inducers deplete folate
Contraindications
- Undiagnosed megaloblastic anaemia (may mask B12 deficiency)
Side effects
- Nausea
- Abdominal distension
- Rarely hypersensitivity
Interactions
- Phenytoin (folic acid reduces phenytoin levels; phenytoin reduces folate absorption)
- Methotrexate (antagonist)
- Trimethoprim (folate antagonist)
Monitoring
- FBC
- Serum B12 level before initiation
Reference: BNF for Children; NICE PH11 (Folic Acid Supplementation); BNF 90. Verify against your local formulary and the latest BNF before prescribing.
Related
Curated clinical cross-links plus same-class fallbacks.
Calculators