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Folic Acid

Last reviewed on RxList: 11/18/2020
Folic Acid Side Effects Center

Medical Editor: John P. Cunha, DO, FACOEP

What Is Folic Acid?

Folic acid is a B complex vitamin 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.

What Are Side Effects of Folic Acid?

Side effects of folic acid are uncommon and may include allergic reactions such as:

Dosage for Folic Acid

The usual therapeutic dosage of folic acid in adults and children (regard less of age) is up to 1 mg daily.

What Drugs, Substances, or Supplements Interact with Folic Acid?

Folic acid may interact with phenytoin and other anticonvulsants, methotrexate, barbiturates, alcohol, pyrimethamine, nitrofurantoin, and antibiotics. Tell your doctor all medications and supplements you use.

Folic Acid During Pregnancy and Breastfeeding

Tell your doctor if you are pregnant or plan to become pregnant before using folic acid; folic acid requirements are markedly increased during pregnancy, and deficiency may harm a fetus. Folic acid passes into breast milk. Folic acid requirements are markedly increased while breastfeeding; however, amounts present in breast milk are adequate to fulfill infant requirements. Consult your doctor before breastfeeding.

Additional Information

Our Folic Acid Side Effects Drug Center provides a comprehensive view of available drug information on the potential side effects when taking this medication.

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.


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Folic Acid Professional Information


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. Other side effects reported in patients receiving 15 mg daily include altered sleep patterns, difficulty in concentrating, irritability, overactivity, excitement, mental depression, confusion, and impaired judgment. Decreased vitamin B12 serum levels may occur in patients receiving prolonged folic acid therapy. In an uncontrolled study, orally administered folic acid was reported to increase the incidence of seizures in some epileptic patients receiving phenobarbital, primidone, or diphenylhydantoin. Another investigator reported decreased diphenylhydantoin serum levels in folatedeficient patients receiving diphenylhydantoin who were treated with 5 mg or 15 mg of folic acid daily.

Read the entire FDA prescribing information for Folic Acid (Folic Acid)


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Related Resources for Folic Acid

© Folic Acid Patient Information is supplied by Cerner Multum, Inc. and Folic Acid Consumer information is supplied by First Databank, Inc., used under license and subject to their respective copyrights.

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