Folic acid

Folic acid is effective in the treatment of megaloblastic anemias due to a deficiency of folic acid (as may be seen in tropical or nontropical sprue) and in anemias of nutritional origin, pregnancy, infancy, or childhood.

• Oral administration is preferred
• Although most patients with malabsorption cannot absorb food folates, they are able to absorb folic acid given orally
• Parenteral administration is not advocated but may be necessary in some individuals (e.g., patients receiving parenteral or enteral alimentation)
• Doses greater than 0.1 mg should not be used unless anemia due to vitamin B 12 deficiency has been ruled out or is being adequately treated with a cobalamin
• Daily doses greater than 1 mg do not enhance the hematologic effect, and most of the excess is excreted unchanged in the urine
• The usual therapeutic dosage
• In adults and children (regard less of age) is up to 1 mg daily
• Resistant cases may require larger doses
• When clinical symptoms have subsided and the blood picture has become normal, a daily maintenance level should be used, i.e., 0.1 mg for infants and up to 0.3 mg for children under 4 years of age, 0.4 mg for adults and children 4 or more years of age, and 0.8 mg for pregnant and lactating women, but never less than 0.1 mg/day
• Patients should be kept under close supervision and adjustment of the maintenance level made if relapse appears imminent
• In the presence of alcoholism, hemolytic anemia, anticonvulsant therapy, or chronic infection, the maintenance level may need to be increased

Folic acid is contraindicated in patients who have shown previous intolerance to the drug.

Administration of folic acid alone is improper therapy for pernicious anemia and other megaloblastic anemias in which vitamin B 12 is deficient.

Allergic sensitization has been reported following both oral and parenteral administration of folic acid. Folic acid is relatively nontoxic in man. Rare instances of allergic responses to folic acid preparations have been reported and have included erythema, skin rash, itching, general malaise, and respiratory difficulty due to bronchospasm. One patient experienced symptoms suggesting anaphylaxis following injection of the drug. Gastrointestinal side effects, including anorexia, nausea, abdominal distention, flatulence, and a bitter or bad taste, have been reported in patients receiving 15 mg folic acid daily for 1 month. …

Except during pregnancy and lactation, folic acid should not be given in therapeutic doses greater than 0.4 mg daily until pernicious anemia has been ruled out. Patients with pernicious anemia receiving more than 0.4 mg of folic acid daily who are inadequately treated with vitamin B 12 may show reversion of the hematologic parameters to normal, but neurologic manifestations due to vitamin B 12 deficiency will progress. …

Take it when you remember, unless it is nearly time for the next dose. Then skip the missed one. Never take two doses at once to make up for it. Check your leaflet, as some medicines are different.