Overview
Folic acid is a B vitamin (B9) essential for DNA synthesis, red blood cell formation, and proper neural tube development in fetuses. It is used to treat folate deficiency and prevent neural tube defects during pregnancy.
Mechanism of Action
Folic acid is converted to tetrahydrofolate (THF) in the body, which acts as a coenzyme in one-carbon transfer reactions involved in DNA synthesis, amino acid metabolism, and red blood cell formation.
Indications
- Treatment of megaloblastic anemia due to folate deficiency
- Prevention of neural tube defects during pregnancy
- Supplementation in patients with malabsorption syndromes
- Adjunct in methotrexate therapy to reduce toxicity
Dosage
Adults: 0.4-1 mg daily orally. Pregnancy: 0.4-0.8 mg daily. Deficiency treatment: 1-5 mg daily. Higher doses may be used for specific conditions under medical supervision.
Contraindications
- Hypersensitivity to folic acid or any component of the formulation
- Untreated vitamin B12 deficiency (may mask hematologic signs while neurological damage progresses)
Side Effects
- Generally well-tolerated
- Rare allergic reactions (rash, itching, bronchospasm)
- Gastrointestinal disturbances (nausea, bloating)
- Bitter taste in mouth
- Sleep disturbances with high doses
Interactions
- Methotrexate: Folic acid may reduce efficacy in cancer treatment but is used to reduce toxicity in rheumatoid arthritis treatment
- Anticonvulsants (phenytoin, phenobarbital, primidone): May reduce serum levels of these drugs
- Sulfasalazine: May reduce folate absorption
- Zinc supplements: High-dose folic acid may impair zinc absorption