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    HomeMedication GuideFolic Acid safety
    B-vitamin supplementSupplement / Nutraceutical

    Folic Acid: What to Know Before You Take It

    Also known as FA-8

    Other names: folic-acid-injectable, folate, vitamin-b9, injectable-folate

    Folic acid (folate, vitamin B9) is an essential B vitamin required for DNA synthesis, cell division, and neural tube development. Injectable folic acid is FDA-approved for folate deficiency states. Injectable use for general wellness or cognitive support is a supplemental off-label use.

    Injectable folic acid is FDA-approved for folate-deficiency anemia and megaloblastic anemia. Use for general wellness, cognitive support, or anti-aging is off-label supplemental use.
    Reviewed by the OmniRx Health clinical team•Last reviewed Jul 4, 2026

    In plain language

    What Folic Acid is used for

    • FDA-approved: folate deficiency, megaloblastic anemia
    • Off-label/supplement: homocysteine management, cognitive support, general wellness

    Taking this medicine

    How it is administered

    • Subcutaneous injection (compounded)

    Read before you decide

    Risks and precautions

    Risks and warnings

    • Nausea, bloating, gas
    • Abdominal cramps
    • Loss of appetite (rare)

    Who should not take it

    • Untreated vitamin B12 deficiency (high-dose folate may mask megaloblastic anemia from B12 deficiency, allowing neurological damage to progress)

    Medication review

    Folic Acid drug interactions

    Folic Acid + MethotrexateIf coadministration cannot be avoided, monitor closely for methotrexate adverse reactions when coadministered with: Oral antibiotics (including neomycin) Antifolate drugs (e.g., dapsone, pemetrexed, pyrimethamine and sulfonamides) Oral or intravenous penicillin or sulfonamide antibiotics Aspirin and other nonsteroidal anti- inflammatory drugs Hepatotoxic products Highly protein-bound drugs (e.g., oral anticoagulants, phenytoin, salicylates, sulfonamides, sulfonylureas, and tetracyclines) Prot…Major interactionFolic Acid + PhenytoinTable 1: Drugs That Affect Phenytoin Concentrations Interacting Agent Examples Drugs that may increase phenytoin serum levels Antiepileptic drugs Ethosuximide, felbamate, oxcarbazepine, methsuximide, topiramate Azoles Fluconazole, ketoconazole, itraconazole, miconazole, voriconazole Antineoplastic agents Capecitabine, fluorouracil Antidepressants Fluoxetine, fluvoxamine, sertraline Gastric acid reducing agents H 2 antagonists (cimetidine), omeprazole Sulfonamides Sulfamethizole, sulfaphenazol…Moderate interactionFolic Acid + Valproic AcidEvidence suggests that folic acid supplementation prior to conception and during the first trimester of pregnancy decreases the risk for congenital neural tube defects in the general population [see Use in Specific Populations ( 8.1 )] .Minor interaction
    Check this against your full medication list in the Interaction Checker

    FDA safety data

    Most-reported side effects

    Based on 246,828 FAERS reports. Reports do not prove the drug caused the effect.

    drug ineffective 25,052fatigue 23,757pain 23,464arthralgia 19,801off label use 17,739rheumatoid arthritis 17,720nausea 15,945diarrhoea 14,504headache 14,471rash 13,829dyspnoea 13,508abdominal discomfort 11,840
    Explore full FDA safety data

    Regulatory record

    FDA recalls (2)

    Class IITerminated · Jan 26, 2022

    CGMP Deviations: Products were exposed to temperatures outside of the products labeled storage conditions.

    Recalling firm: CARDINAL HEALTHCARE

    Class IITerminated · Mar 15, 2021

    CGMP Deviations: Intermittent exposure to temperature excursion during storage.

    Recalling firm: Cardinal Health Inc.

    Common questions

    Patient questions

    Is injectable folic acid better than oral folate?

    For most people, oral folic acid or methylfolate supplements are sufficient. Injectable folic acid is indicated for malabsorption syndromes or confirmed deficiency states where oral absorption is impaired. A licensed provider or dietitian can assess your folate status.

    Who needs injectable folic acid?

    Injectable folic acid (FDA-approved for folate-deficiency anemia and megaloblastic anemia) is used in patients who cannot absorb oral folate, such as those with severe malabsorption, certain bowel conditions, or who are receiving parenteral nutrition. Most people with folate deficiency respond to oral supplementation.

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    This information is educational — not medical advice.

    This page is provided for general educational purposes and summarizes publicly available data from sources such as the U.S. Food & Drug Administration. It is not a substitute for the judgment of a licensed clinician and should not be used to start, stop, or change any medication. It may be incomplete or out of date, and individual circumstances vary. Always talk with your prescriber or pharmacist about your specific medications and health conditions. If you think you may have a medical emergency, call 911.

    Sources & References

    Learn more about where our data comes from and how we write and review medical content.