The U.S. Food and Drug Administration does not strictly regulate herbs and supplements. There is no guarantee of strength, purity or safety of products, and effects may vary. You should always read product labels. If you have a medical condition, or are taking other drugs, herbs, or supplements, you should speak with a qualified healthcare provider before starting a new therapy. Consult a healthcare provider immediately if you experience side effects.


Avoid in people with known allergy or sensitivity to product ingredients in folic acid-containing supplements.

Side Effects and Warnings

Folate is likely safe when added to foods in the following amounts: in breakfast cereals, below 400 micrograms per serving; in infant formula, 4 micrograms per 100 kilocalories of infant formula; in corn grits, 1 milligram per pound; in meal-replacement products, 200-400 micrograms per serving, with the amount depending on whether the food is used once or more than once daily.

Use cautiously if taken above the suggested or maximum daily intake levels.

Folate may cause bitter taste, bloating, blood flow problems (caused by narrowed vessels), breathing difficulty, changes in urine color, confusion, cramps, diarrhea, dizziness, fatigue, gas, hair loss, headache, impaired judgment, increased asthma risk (in children of women taking folic acid during late pregnancy), increased cancer risk, increased seizure frequency, inflammation (such as in the mouth), lung muscle spasms, mood swings (excitability or irritability), nausea, overactivity, psychotic behavior, skin symptoms (flushing, hives, itching, rash, and redness), sleep problems, vivid dreaming, and weight changes.

Folate may cause low blood pressure. Caution is advised in people taking drugs or herbs and supplements that lower blood pressure.

Folate may lower blood sugar levels. Caution is advised in people with diabetes or low blood sugar, and in those taking drugs, herbs, or supplements that affect blood sugar. Blood sugar levels may need to be monitored by a qualified healthcare professional, including a pharmacist, and medication adjustments may be necessary.

Use cautiously in combination with aspirin or in supplemental doses above the maximum daily intake without the care of a medical professional. Injections of folic acid containing benzyl alcohol should only be used under the care of a doctor.

Use cautiously in people who have or are at risk of anemia, cancer, lung disorders, malaria, nervous system disorders, seizure disorders, skin conditions, and stomach problems.

Avoid using with a combination of B vitamins after heart surgery or in people taking anticancer agents or folic acid antagonists (blockers), unless prescribed by a healthcare professional.

Avoid in people with known allergy or sensitivity to product ingredients in folic acid-containing supplements.

Pregnancy and Breastfeeding

The U.S. Preventive Services Task Force and other groups suggests that all women planning to be pregnant take a daily supplement containing 0.4-0.8 milligrams (400-800 micrograms) of folic acid. It is suggested that all women capable of becoming pregnant consume folate in order to reduce the risk of the fetus developing birth defects.

Folic acid is likely safe to use during breastfeeding under the supervision of a qualified healthcare provider.

This evidence-based monograph was prepared by The Natural Standard Research Collaboration