Folic acid
Also sold as: Folvite
No prescription neededVitamins and minerals
Comes as:Tablet
Usual adult dose
To prevent birth defects: 400 micrograms (0.4 mg) once a day, ideally from before pregnancy until the end of the third month. For anaemia caused by lack of folate: usually 5 mg once a day, as advised by your doctor.
Your doctor may give you a different dose. Children's doses depend on weight.
Side effects
Common
- rare at normal doses
- mild stomach upset
Serious — get help
Stop taking it and see a doctor straight away if you notice:
- severe allergic reaction (rash
- swelling of face or throat
- difficulty breathing)
Do not take it, or take care, if
- Vitamin B12 deficiency that has not been treated — folic acid alone can hide it (check with a doctor)
- Some cancers being treated (ask your doctor)
Interactions
Medicines that can react with this one.
Moderate1 medicineTake together only with care. Ask your doctor or pharmacist.
- Phenytoin
Folic acid can lower phenytoin levels and seizure control; the doctor may check levels.
Minor1 medicineUsually not a problem, but tell your doctor.
- Sulfasalazine
Sulfasalazine reduces folic acid absorption; a supplement may be advised.