Side Effects of Folic Acid Tablets

Folic acid is safe if taken in the recommended dosage; however, its overuse may cause some side effects in the long run.
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Folate, or vitamin B9, is the active ingredient in folic acid. It is crucial during pregnancy and beneficial in treating various chronic conditions. As a supplement, folic acid is safe if taken in the recommended dosage. However, its overuse may cause some side effects in the long run.


What Is Folic Acid?

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You can find folic acid in dietary supplements and fortified foods. This compound is the synthetic form of folate, one of the group of B vitamins needed for the production and division of new cells, including the skin, hair, muscles and brain. It helps your body make red and white blood cells, and it's particularly important in DNA synthesis.

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Folic acid works together with vitamins B6 and B12 to control amino acid function in your blood. When proteins break down, elevated levels of amino acids, such as homocysteine, may be found in the bloodstream, which may increase your risk of cardiovascular disease. Promising but not yet proven benefits of folate include treating depression and autism, and reducing the risk of cancer.


Folic acid is essential for growth, especially in developing unborn babies. Taking folic acid before becoming pregnant and during early pregnancy may help prevent neural tube defects in babies.

Neural tube defects are major birth malformations in an infant's brain or spine. Since about half of all pregnancies are unplanned — as the Centers for Disease Control and Prevention (CDC) points out, most women and teenage girls who are planning to have a child soon may benefit from folic acid supplements. Taking a daily supplement, such as Folvite, during pregnancy may also decrease the likelihood of having a premature or low birth-weight baby.


Read more: 4 Health Benefits of Taking Folic Acid in Non-Pregnant Women

How Much Do You Need?

Recommendations have been established for the amount of folate you need each day for good health. These amounts are measured in dietary folate equivalents (DFE) because your body absorbs more folic acid from fortified foods and supplements than from the folate found naturally in foods.


Depending on your age, the recommended amount of folate you should strive for each day is as follows, according to the National Institutes of Health (NIH):

  • Birth to 6 months: 65 micrograms
  • Infants 7 to 12 months: 80 micrograms
  • Children 1 to 3 years: 150 micrograms
  • Children 4 to 8 years: 200 micrograms
  • Children 9 to 13 years: 300 micrograms
  • Ages 14 years and older: 400 micrograms
  • Pregnant women: 600 micrograms
  • Breastfeeding women: 500 micrograms



The CDC recommends women of reproductive age to take 400 micrograms of supplemental folic acid each day in addition to consuming foods rich in folate to help prevent birth defects in their babies.

Foods naturally high in folate include beans, dark green leafy vegetables, soy products, some fruits and vegetables and whole grains. Those that top the list for being highest in folate are:


  • Edamame, cooked — 121 percent of the daily value (DV) per cup
  • Lentils, cooked — 90 percent of the DV per cup
  • Asparagus, cooked — 67 percent of the DV per cup
  • Spinach, cooked — 66 percent of the DV per cup
  • Broccoli, cooked — 42 percent of the DV per cup
  • Avocados — 41 percent of the DV per fruit

Folic acid is added to many foods, including:

  • Enriched bread, flour, cornmeal, pasta and rice
  • Fortified breakfast cereals
  • Fortified corn masa flour, used to make corn tortillas and tamales


Read more: Fruits and Vegetables Containing Folic Acid

Are You Deficient in Folate?

Cooking and processing food can easily inactivate folate. Its levels may be reduced by several factors, including:

  • Poor or restricted diet
  • Chronic disease
  • Diabetes and other metabolic problems
  • Cancer
  • Smoking
  • Alcohol use
  • Medical conditions, such as celiac disease, which inhibit nutrient absorption
  • Medications, such as mood stabilizers, L-dopa, statins, oral antidiabetic drugs and chemotherapy drugs


Deficiencies seem to be more common in teenage girls, ages 14 to 18 years, and women, ages 19 to 30 years, as the NIH points out.

If you are at risk for folate deficiency, you may experience a number of symptoms, including a blood disorder known as megaloblastic anemia, which can cause:


  • Weakness
  • Fatigue
  • Trouble concentrating
  • Irritability
  • Headache
  • Heart palpitations
  • Shortness of breath

Folate deficiency may also cause:

  • Open sores in the mouth and on tongue
  • Changes in the color of the skin, hair or fingernails

Vitamin and Folate Supplements

Folic acid comes in tablet form. It is available in individual supplements, such as Folvite, multivitamin mineral pills, prenatal vitamins and B-complex dietary supplements.

Folic acid tablets are usually taken once a day. Follow the directions on your prescription label carefully and take the pill exactly as directed. If you're taking folic acid to treat a deficiency, you'll likely feel better within 24 hours, but don't stop taking it until your doctor says it's OK to do so.

Although too much folate from your diet isn't harmful, folic acid supplements or fortified foods in amounts that exceed the recommended tolerable upper levels may be detrimental to your health. According to the NIH, daily upper limits for folic acid have been established as a guideline for safe intake and are dependent on age. These amounts are:

  • Children 1 to 3 years: 300 micrograms
  • Children 4 to 8 years: 400 micrograms
  • Children 9 to 13 years: 300 micrograms
  • Teens 14 to 18 years: 800 micrograms
  • Adults 19 years and older: 1,000 micrograms

Side Effects and Interactions

When used in an appropriate dosage, folic acid is likely safe. However, the NIH warns that high doses of folic acid supplements, such as Folvite, may mask vitamin B12 deficiency.

Undetected, neurological consequences may become irreversible, including anemia and cognitive decline associated with low levels of vitamin B12. In addition, exceeding the recommended dosage may increase your risk of colorectal cancer and possibly other forms of cancer as well.


Although not common for most individuals, folic acid can cause an allergic reaction and some side effects that require medical attention. According to the Mayo Clinic, these may include:

  • Fever
  • General weakness or discomfort
  • Reddened skin
  • Shortness of breath
  • Skin rash or itching
  • Tightness in chest
  • Trouble breathing
  • Wheezing

Folate function may be compromised by interacting with certain drugs. Always consult your doctor before starting on a regime of folic acid supplements if you take any medications, including prescription, over-the-counter or herbal products. Possible interactions include, as reported by the Mayo Clinic:

  • Anticonvulsants: Taking folic acid with certain medications, such as Cerebyx, Dilantin, Phenytek or Mysoline, might decrease the drug's concentration in your blood.
  • Barbiturates: Taking folic acid with any medication that acts as a central nervous system depressant may reduce the drug's effectiveness.
  • Methotrexate (Trexall): Taking folic acid with some cancer-treating medications could interfere with its effectiveness.
  • Pyrimethamine (Daraprim): Taking folic acid in combination with antimalarial drugs might reduce the drug's effectiveness.




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