Folic Acid: Click for Uses, Side Effects and Dosage

What is oral folic acid? How is oral folic acid used?

Folic acid and folate are water-soluble forms of vitamin B9 that is naturally found in many of the foods we eat. Folate occurs naturally in food while folic acid is the man-made form of this important vitamin. Common dietary sources of folate include

  • green leafy vegetables,
  • fruits and fruit juices,
  • nuts,
  • beans,
  • peas,
  • dairy products,
  • poultry,
  • meats,
  • eggs,
  • seafood,
  • grains,
  • yeast,
  • beef kidney, and
  • beef liver.

Additionally, folic acid is added to many food products (fortified) and is available as a dietary supplement.

Folic acid is an important vitamin that is needed for the proper development of the human body. Folic acid is needed to make DNA and other genetic material and for the synthesis of red blood cells. Folic acid deficiency can cause megaloblastic anemia, a red blood cell disorder that can cause symptoms of weakness, fatigue, trouble concentrating, irritability, headache, abnormal heartbeats, and shortness of breath. Folic acid is necessary for healthy skin, hair, and nails. Therefore, folic acid deficiency may cause sores in the mouth, and changes in the color of the skin, hair, or fingernails. Additionally, maintaining healthy levels of folic acid during pregnancy is very important. Pregnant women who do not get enough folic acid are at risk of giving birth to babies with neural tube defects such as spina bifida. Folic acid deficiency during pregnancy may also increase the likelihood of having a premature delivery or a low weight baby.

What brand names are available for folic acid-oral?

FA-8, Folacin, Folic Acid, GNC Folic Acid 400, and many more

Is folic acid-oral available as a generic drug?


Do I need a prescription for folic acid-oral?


What are the side effects of oral folic acid?


Folic acid supplementation is generally thought to be safe for human use. However, in rare cases, allergic or anaphylactoid reactions have occurred. Patients experiencing any signs or symptoms of a severe allergic reaction including hives, difficulty breathing or swallowing, and shortness of breath should seek emergency medical help.

What is the dosage for oral folic acid?


  • For folic acid deficiency, the typical dose is 250 mcg (micrograms) to 1 mg (milligrams) per day.
  • For preventing neural tube defects, at least 400 mcg of folic acid per day from supplements or fortified food should be taken by women capable of becoming pregnant and continued through the first month of pregnancy. Women with a history of previous pregnancy complicated by such neural tube defects usually take 4 mg per day beginning one month before and continuing for three months after conception.
  • For reducing colon cancer risk, 400 mcg per day.
  • For treating high levels of homocysteine in the blood, 200 mcg to 15 mg/day has been used, although 800 mcg to 1 mg/day appears to be more effective.
  • In people with end-stage renal disease, high homocysteine levels may be more difficult to treat, and doses of 800 mcg to 40 mg/day have been used. Other dosage plans such as 2.5 to 5 mg 3 times weekly have also been used. Doses higher than 15 mg daily do not seem to be more effective.
  • For improving the response to medications for depression, 200 to 500 mcg daily has been used.
  • For vitiligo, 5 mg is typically taken twice daily.
  • For reduction of toxicity associated with methotrexate therapy for rheumatoid arthritis (RA) or psoriasis, 1 mg/day is probably enough, but up to 5 mg/day may be used.
  • For preventing macular degeneration, folic acid 2.5 mg, vitamin B12 (cyanocobalamin) 1000 mg, and vitamin B6 (pyridoxine) 50 mg daily.


For gum problems due to a drug called phenytoin (6 to 15 years), 500 mcg of folic acid daily has been used.

The adequate intakes (AI) for infants are 65 mcg for infants 0 to 6 months and 80 mcg for infants 7 to 12 months of age.

From childhood to adulthood

The recommended dietary allowances (RDAs) for dietary folate equivalent (DFE), including both food folate and folic acid from fortified foods and supplements are:

  • Children 1 to 3 years, 150 mcg;
  • Children 4 to 8 years, 200 mcg;
  • Children 9 to 13 years, 300 mcg;
  • Adults over 13 years, 400 mcg;
  • Pregnant women 600 mcg; and
  • Breastfeeding women, 500 mcg.

The tolerable upper intake levels (UL) of folate are:

  • 300 mcg for children 1 to 3 years of age,
  • 400 mcg for children 4 to 8 years,
  • 600 mcg for children 9 to 13 years,
  • 800 mcg for adolescents 14 to 18 years, and
  • 1 mg for everyone over 18 years of age.

Which drugs or supplements interact with oral folic acid?

Coadministration of folic acid with cholestyramine (Prevalite, Questran, Questran Light) may decrease the absorption of folic acid. Patients taking both medications are advised to take folic acid 1 hour before or 4-6 hours after cholestyramine.

Folic acid may interfere with methotrexate (Trexall, Rhuematrex, MTX), a medication used to treat certain cancers. Methotrexate works by decreasing the effects of folic acid and therefore, taking these medications together may decrease the effectiveness of methotrexate.

Folic acid supplements may reduce blood levels of certain anti-seizure medications including phenytoin (Dilantin), fosphenytoin (Cerebyx), primidone (Mysoline) and phenobarbital (Luminal) thereby reducing their effectiveness. Also, these medications may also reduce the blood levels of folic acid.

Sulfasalazine (Azulfidine) may decrease the body's ability to absorb folic acid.

Folic acid may decrease the effectiveness of pyrimethamine (Daraprim), a medicine used to treat parasite infections.


According to the USDA, there is no difference between a “portion” and a “serving.”
See Answer

Is oral folic acid safe to take if I’m pregnant or breastfeeding?

Adequate intake of folic acid during pregnancy is very important for the health of the mother and her baby. Clinical evidence shows that fetal neural defects can be prevented with folic acid supplementation in folic acid deficient mothers.

Folic acid is safe for use during pregnancy. However, pregnant women are advised to speak to their doctor or pharmacist before starting supplementation.

Maintaining adequate folic acid intake is important for nursing mothers. Women who are unable to get enough dietary folic acid may require supplementation to achieve adequate intake during lactation. The American Academy of Pediatrics (AAP) considers use of folic acid supplements to be compatible with breastfeeding.

What else should I know about oral folic acid?

What preparations of folic acid-oral are available?

  • Preservative free oral capsules: 5 and 20 mg
  • Solution for injection: 5 mg/ml (10 ml)
  • Oral tablets: 400 mcg, 800 mcg, 1 mg
  • Preservative free oral tablets: 800 mcg dye free, 400 and 800 mcg
How should I keep folic acid-oral stored?

Folic acid preparations should be stored at room temperature between 15 C and 30 C (59 F and 86 F).

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