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Overview: Folic acid is a form of vitamin B9 (folate) that is used to increase vitamin B9 levels. It is available in various forms, including over-the-counter supplements and prescriptions. Folic acid is usually well tolerated. Before taking folic acid, tell your health care provider about all of your health conditions and any medicines or supplements you may be taking.

Uses

What is folic acid used for?

Folic acid is a form of vitamin B9 that is commonly used for the following.

  • To prevent or treat low vitamin B9 levels from various causes
  • To help maintain vitamin B9 levels in certain people with a type of anemia called megaloblastic anemia
  • To help prevent serious birth defects, called neural tube defects (such as spina bifida), in people who are pregnant or could become pregnant

Folic acid may also be used for other conditions as determined by your health care provider.

How does folic acid work (mechanism of action)?

Folic acid is a form of vitamin B9. Your body uses vitamin B9, also known as folate, to make DNA and to help your cells grow and divide.

In the United States, most people get enough folate from their diet. It is found in beef liver, vegetables, fruits, nuts, beans, and peas. It is also found in many fortified cereals and grains. For most adults, the recommended daily intake of folate is 400 micrograms (mcg). However, some people either do not get enough from their diet or have trouble absorbing it. When this happens, you can take folic acid to replace what you are not getting from your diet.

How is folic acid supplied (dosage forms)?

Brands and other names

  • Folicet
  • Folvite

Dosage forms and strengths

Folic acid, also known as vitamin B9, is available as a dietary supplement in various strengths and dosage forms. Folic acid is also available as a prescription in the following dosage forms and strengths.

  • 1 mg oral tablets

Folic acid is also commonly found as an ingredient in multivitamins, prenatal vitamins, and B-complex vitamins.

How should I store folic acid?

Storage requirements for folic acid may vary based on the product you are taking. Check your product label. Folic acid should usually be stored at room temperature, between 68 F and 77 F (20 C and 25 C). It can be exposed to temperatures between 59 F and 86 F (15 C and 30 C) for shorter periods of time, such as when transporting it. Store in a cool, dry place. If you are not sure how to store it, ask your pharmacist.

Side Effects

What are the most common side effects of folic acid?

Folic acid is usually well tolerated. Tell your health care provider if you have any side effects that bother you.

Contact your health care provider if you think you are having a side effect of a medicine. In the U.S., you can report side effects to the FDA at www.fda.gov/medwatch or by calling 800-FDA-1088 (800-332-1088). In Canada, you can report side effects to Health Canada at www.health.gc.ca/medeffect or by calling 866-234-2345.

What are the serious side effects of folic acid?

While less common, the most serious side effects of folic acid are described below, along with what to do if they happen.

Severe Allergic Reactions. Folic acid may cause allergic reactions, which can be serious. Stop taking folic acid and get help right away if you have any of the following symptoms of a serious allergic reaction.

  • Breathing problems or wheezing
  • Racing heart
  • Fever or general ill feeling
  • Swollen lymph nodes
  • Swelling of the face, lips, mouth, tongue, or throat
  • Trouble swallowing or throat tightness
  • Itching or skin rash
  • Bumps on the skin called hives that can be red, pink, white, or brown depending on your skin tone
  • Nausea or vomiting
  • Dizziness, feeling lightheaded, or fainting
  • Stomach cramps
  • Joint pain

Warnings & Precautions

Who should not use folic acid?

Allergies to Ingredients. People who are allergic to any of the following should not take folic acid.

  • Folic acid
  • Folicet
  • Folvite
  • Any of the ingredients in the specific product

Your pharmacist can tell you all of the ingredients in the specific folic acid products they stock.

What should I know about folic acid before using it?

There are multiple forms of folic acid available. If folic acid was prescribed to you by a health care provider, take it as prescribed. If you are taking folic acid as an over-the-counter supplement, follow the instructions that come with the product or take it as your health care provider recommends. If you have any questions about how to take folic acid, talk to your health care provider.

Do not share folic acid that was prescribed for you by a health care provider with other people, even if they have the same condition as you. It may harm them.

Keep folic acid out of the reach of children.

Folic acid is measured in a unit known as dietary folate equivalents (or DFE). This is because your body absorbs folic acid from supplements better than the folate found in foods. The recommended daily intake of folate for most adults is 400 mcg DFE. This is the same as 240 mcg of folic acid from supplements.

If you are using a liquid form of folic acid, use an accurate measuring device to measure your dose. A household spoon is not an accurate measuring device and may cause you to take the wrong dose. Ask your pharmacist what measuring device to use.

What should I tell my health care provider before using folic acid?

Tell your health care provider about all of your health conditions and any prescription or over-the-counter (OTC) medicines, vitamins/minerals, herbal products, and other supplements you are using. This will help them know if folic acid is right for you.

In particular, make sure that you discuss any of the following.

Low Vitamin B12 Levels. Taking folic acid might mask the symptoms of low vitamin B12 levels or make the symptoms worse. Your health care provider will let you know if you should have your vitamin B12 levels checked before taking folic acid.

MTHFR Gene Mutation. Some people have a change in their MTHFR gene, known as an MTHFR gene mutation. This gene tells the body to convert folic acid to its active form. People with an MTHFR gene mutation might not convert as much folic acid to its active form. Tell your health care provider if you have an MTHFR gene mutation. They will let you know whether you should take folic acid and how much you should take.

Other Current and Past Health Conditions. Tell your health care provider if you have or have had any of the following.

Other Medicines and Supplements. Folic acid may interact with other medicines and supplements. Before taking folic acid, tell your health care provider about any prescription or over-the-counter (OTC) medicines, vitamins/minerals, herbal products, and other supplements you are using. See the Interactions section for more details.

Pregnancy. It is important to make sure you are getting enough folic acid while pregnant. Tell your health care provider if you are pregnant or plan to become pregnant. Your health care provider will let you know if you should take folic acid while you are pregnant or trying to get pregnant.

Breastfeeding. Folic acid passes into breast milk. Tell your health care provider if you are breastfeeding or plan to breastfeed. Your health care provider will let you know if you should take folic acid while breastfeeding.

Interactions

Does folic acid interact with foods or drinks?

There are no known interactions between folic acid and foods or drinks.

It is unknown if drinking alcohol will affect folic acid, but drinking large amounts of alcohol may lower the levels of vitamin B9 in your body. It is best to limit the amount of alcohol you drink.

Does folic acid interact with other medicines (drug interactions)?

Always tell your health care provider about any prescription or over-the-counter (OTC) medicines, vitamins/minerals, herbal products, and other supplements you are using.

In particular, make sure that you discuss if you are using any of the following before using folic acid.

  • Any medicine for seizures, such as carbamazepine, phenobarbital, phenytoin, or primidone
  • Divalproex sodium, valproate sodium (Depakote and others), or valproic acid, which are medicines used for seizures and other conditions
  • Methotrexate (Trexall and others), which is a medicine commonly used for rheumatoid arthritis or certain types of cancer
  • Pyrimethamine (Daraprim), which is a medicine used to treat certain types of serious infections

This may not be a complete list of medicines that can interact with folic acid. Always check with your health care provider.

Does interact with other drugs you are taking?

Enter your medication into the WebMD interaction checker

Overdose/Missed Dose

What should I do if I accidentally use too much folic acid?

If you or someone else has used too much folic acid, get medical help right away, call 911, or contact a Poison Control center at 800-222-1222.

What should I do if I miss a dose of folic acid?

If you miss a dose, take it as soon as you remember. If it is almost time for your next dose, skip the missed dose and only take the next dose. Do not take double or extra doses.