Key takeaways:
Folic acid (also known as vitamin B9) is one important part of health and development. It helps prevent anemia and neural tube defects, among other uses.
Many years ago, it was suspected that large amounts of folic acid could promote seizures. But with more research available, that’s no longer a concern.
It’s important to be aware of drug interactions between folic acid supplements and certain anti-seizure medications. Make sure to talk to your healthcare provider if you’re planning on taking both.
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Fact or myth? That’s a question pharmacists and healthcare providers get asked from time to time when it comes to supposed medication side effects or interactions.
Some of these common safety questions are about folic acid and its effect on anti-seizure medications. Although folic acid is needed to build and develop healthy cells, there have been concerns over whether large amounts might promote seizures. Some of these concerns are outdated and new data has lessened these concerns, while others are still important to consider.
Let’s break down the basics about folic acid and its relation to anti-seizure medications.
What is folic acid used for?
Folic acid is a B vitamin, specifically vitamin B9. It can be found in many fortified foods and several vitamins and supplements.
As a dietary supplement, folic acid can be used to treat certain types of anemia, prevent neural tube defects (birth defects of the brain, spine or spinal cord), and treat folate deficiency.
Folic acid supplementation comes in both oral and injectable forms. A typical dose is 1 mg (1,000 mcg) daily, but this dose may change depending on your age, medical history, and specific needs.
The oral form is more common than the injectable version, and it can be found in over-the-counter (OTC) products like multivitamins, prenatal vitamins, and even stand-alone products.
Is folic acid the same as folate?
Not exactly. Folic acid and folate are different versions of vitamin B9.
Folic acid is a synthetic (lab-made) form of vitamin B9 that’s found in dietary supplements and fortified foods. This includes enriched cereals, breads, and rice. It’s the only type of vitamin B9 shown to prevent neural tube defects.
Meanwhile, folate is a natural form of vitamin B9 that’s found in foods. Here are some examples of foods with high levels of folate:
Beans
Nuts
Dark green leafy vegetables
Brussels sprouts
Citrus fruits
How do folic acid supplements work?
First, folic acid has to be absorbed into your body before it can start working. In general, folic acid supplements are better absorbed by your body than folate from food sources.
Once it’s absorbed, it helps your body make DNA and plays a role in cell growth. This is especially important for unborn babies during pregnancy. Folic acid also works with vitamin B12 to make red blood cells and help iron function properly.
Do folic acid levels affect seizure control?
This doesn’t appear to be the case.
Several decades ago, it was suspected that large amounts of folic acid could promote seizures. But since then, researchers have gathered more data, and that connection is no longer a concern.
Actually, some recent research now suggests the opposite. For example, one study found that folic acid supplementation improved seizure control in folate-deficient children who were taking anti-seizure (also known as antiepileptic) medications.
However, some anti-seizure medications can mess with your folate levels. Antiepileptic medications causing folate deficiency is an important concern, as we’ll discuss below.
What does the research say about folic acid interacting with anti-seizure medications?
If you have a seizure condition, you may be taking one or more anti-seizure medications. Some anti-seizure medications can interfere with how folic acid absorbs into your body or breaks down, possibly leading to folate deficiency.
Phenytoin (Dilantin, Phenytek), carbamazepine (Tegretol), and barbiturate medications like phenobarbital have been shown to reduce folate levels by up to 90%. Folic acid supplementation may be recommended by a healthcare provider if you’re taking any of these medications. This is especially important for women of child-bearing age, since there is a higher risk of neural tube defects.
Folic acid supplements may interfere with one type of anti-seizure medication: phenytoin. The supplements can make phenytoin not work as well, which could mess with seizure control. So your healthcare provider may adjust the dose of phenytoin if this is the case. But, this issue isn’t much of a concern with the other anti-seizure medications, such as valproic acid.
Do any other medications interact with folic acid?
Yes. Some other medications can also interact with folic acid. Some examples include:
Methotrexate (Trexall)
Pyrimethamine (Daraprim)
Sulfasalazine (Azulfidine)
Methotrexate is used to treat many health conditions, including certain types of cancer and autoimmune disorders. Pyrimethamine helps treat toxoplasmosis, an infection caused by a parasite. They both block an enzyme (protein) called dihydrofolate reductase, which normally works by using folate to make DNA.
Taking folic acid supplementation with these medications can interfere with how they work. But when it comes to methotrexate, folic acid is actually sometimes used as a supplement to help control methotrexate side effects, especially when it’s being used to treat autoimmune disorders.
Sulfasalazine is different. It can block how well folic acid is absorbed or broken down in the body. This could lead to a folate deficiency if the interaction is not properly addressed.
Managing these interactions is a bit complex, so you should talk with your healthcare provider and pharmacist before taking medications like these with folic acid.
Should I talk to my healthcare provider before taking folic acid if I’m taking an anti-seizure medication?
If you’re taking any of the medications listed above, it’s important to talk to your healthcare provider and pharmacist. It’s also helpful to give them an updated list of all the medications you take to let them check for other potential drug interactions. An interaction could potentially change the amount of folic acid supplementation that’s recommended or even how well medications like phenytoin work.
The bottom line
Vitamin B9, also known as folic acid, is important for healthy cell growth and development. But, its safety has been questioned in the past when taken alongside anti-seizure medications. Certain anti-seizure medications can reduce folate levels in the body, causing folate deficiency. And folic acid can reduce phenytoin levels in the body, affecting seizure control.
If you’re taking an anti-seizure medication, it’s important to talk to your healthcare provider and pharmacist before starting folic acid supplements.
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References
A-S Medical Solutions, LLC. (2021). Sulfasalazine [package insert].
Caudill, M.A., (2010). Folate bioavailability: implications for establishing dietary recommendations and optimizing status. The American Journal of Clinical Nutrition.
Centers for Disease Control and Prevention. (2017). Folic acid safety, interactions, and effects on other outcomes.
Centers for Disease Control and Prevention. (2020). Facts about neural tube defects.
Centers for Disease Control and Prevention. (2020). MTHFR gene, folic acid, and preventing neural tube defects.
DailyMed. (2022). Folic acid injection, solution.
Deopa, B., (2018). Effect of folic acid supplementation on seizure control in epileptic children receiving long term antiepileptic therapy. The Indian Journal of Pediatrics.
Epilepsy Foundation. (2019). Epilepsy and folic acid.
Fernández-Villa, D., et al. (2019). Folic acid antagonists: Antimicrobial and immunomodulating mechanisms and applications. International Journal of Molecular Sciences.
Mahmood, L., (2014). The metabolic processes of folic acid and vitamin B12 deficiency. Journal of Health Research and Reviews.
Morrell, M. J., (2002). Folic acid and epilepsy. Epilepsy Currents.
National Institutes of Health. (2021). Folate: Fact sheet for consumers.
Preferred Pharmaceuticals Inc. (2022). Folic acid [package insert].
Reynolds, E. H., (1973). Anticonvulsants, folic acid, and epilepsy. The Lancet.
