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What are the Side Effects of Folic Acid?

Henry Gaudet
Henry Gaudet

The side effects of folic acid are rare. As with any medication, treatment, or supplement, there are, however, potential risks, especially at higher doses. Before exploring these risks, it is important to understand the role of folic acid in maintaining good health, as well as the need for folic acid supplements.

Folic acid, also known as folacin or vitamin B9, has a crucial role in producing healthy new cells and maintaining the body’s metabolism. It occurs naturally in foods such as leafy green vegetables, beans, peas, and nuts. Still, many people do not get enough folic acid from dietary sources, and since the vitamin is water soluble, it cannot be stored in the body. To meet this need, folic acid supplements are widely available; folic acid is also included in many multivitamins.

Legumes contain folic acid.
Legumes contain folic acid.

Women who are pregnant or are considering childbirth typically need higher levels of folic acid than most people, and supplements are generally recommended. Insufficient levels of folic acid early in pregnancy can increase the chance of birth defects such as Spina Bifida. Folic acid has also been used to treat schizophrenia, arthrosclerosis, heart disease, depression, diarrhea, and anemia. Some medications cause the body to metabolize folic acid more quickly and a supplement is often given to people on such prescriptions to counteract this deficiency.

A banana bag containing folic acid.
A banana bag containing folic acid.

While side effects of folic acid are uncommon, they do occur with varying degrees of severity. Many side effects are relatively minor, including gastric complaints such as flatulence, bloating, loss of appetite, and nausea. Other less serious side effects include a reduced ability to concentrate, redness of the skin, a general weakness or lethargy, a bitter taste in the mouth, and insomnia. Anyone experiencing any of these side effects should consult a doctor, who may adjust the dosage, suggest a different supplement, or even discontinue the treatment as necessary.

Folic acid might cause insomnia.
Folic acid might cause insomnia.

Some side effects of folic acid are known to occur primarily when taking large doses. People taking more than 15,000 micrograms (mcg) – well in excess of the Recommended Daily Allowance (RDA) of 400 mcg – have an increased incidence of many of the side effects reported at lower dosages. Additional symptoms including stomach pain and bloating, changes in normal sleep patterns, and seizures have also been observed.

An allergic reaction to folic acid may include hives.
An allergic reaction to folic acid may include hives.

Some of the most serious side effects of folic acid include allergic reactions, which can include rashes, hives, and swelling. Allergic reactions can be especially dangerous as swelling may make breathing difficult or even obstruct the airway. Anyone experiencing any of these side effects of folic acid should stop taking the supplement and seek medical assistance immediately.

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    • Legumes contain folic acid.
      By: Stefano Neri
      Legumes contain folic acid.
    • A banana bag containing folic acid.
      By: beerkoff
      A banana bag containing folic acid.
    • Folic acid might cause insomnia.
      By: arekmalang
      Folic acid might cause insomnia.
    • An allergic reaction to folic acid may include hives.
      By: Jürgen Fälchle
      An allergic reaction to folic acid may include hives.