What are the most common side effects of folic acid?

It’s well known that folic acid is an important vitamin, particularly for anyone who’s pregnant. Indeed, healthcare services around the globe suggest taking folic acid to support proper growth of a baby during early pregnancy.¹ 

Nevertheless, as with any supplement, folic acid can lead to side effects among some people. Although most people can take folic acid without experiencing side effects, it’s good to know what they could be so you can spot them early if needed and seek medical advice.

If you are pregnant or planning to get pregnant, discuss folic acid supplementation with your healthcare team before you begin to learn more about whether folic acid is right for you and what dosage you should take.²

What are the side effects of taking folic acid?

Most people who take folic acid supplements don’t notice any side effects. When side effects do happen, they are usually mild and temporary. Some people may feel a little nauseous, have an upset stomach, or notice a reduced appetite. These often improve as your body gets used to the supplement, or by taking folic acid with meals or at a different time of day.

In rare cases, a more serious allergic reaction can occur. Signs to watch for include swelling of the face, lips, tongue or throat, trouble breathing, or a rash that spreads quickly, becomes itchy, or looks unusual. If any of these happen, seek medical attention immediately.³⁴

Can folic acid make you feel sick?

Some people feel a bit nauseous when they start taking folic acid supplements.⁵ This can be tricky for women in early pregnancy, since nausea is common then too, making it hard to tell whether it’s from the folic acid or pregnancy itself.

One way to make it easier is to take the supplement at a time of day when you usually feel less queasy. For example, if mornings are the toughest, try taking it in the evening. Taking folic acid with food can also help reduce nausea.⁶

If the nausea keeps bothering you, it’s a good idea to check in with a healthcare professional. They can help figure out whether the supplement or something else is causing the discomfort.

Can folic acid delay your period?

There isn’t any solid research showing that folic acid directly affects your menstrual cycle. That said, some people have noticed changes, like a later start to their period, while taking folic acid supplements.⁷

It’s worth remembering that period changes are very common and can happen for lots of reasons, such as stress, gaining or losing weight. One important point is that a missed or late period is often one of the first signs of pregnancy for many women.⁸

If you notice a change in your cycle and feel concerned, it’s always a good idea to check in with a healthcare professional, especially if you’re trying to get pregnant.

Does folic acid make you sleepy?

Folic acid on its own doesn’t make you feel sleepy or drowsy. In your body, it gets converted into folate, which is the form your body actually uses. Folate can help fight tiredness and fatigue by supporting normal red blood cell production and energy metabolism.⁹

That is, while folic acid supplements won’t put you to sleep, in the long term they will in fact decrease perceptions of tiredness if you had a folic acid deficiency in the first place.

Can folic acid cause stomach upset?

Some people notice tummy troubles when taking folic acid. This can show up as bloating, stomach cramps, or even diarrhoea.¹⁰

These side effects are usually mild and not dangerous. Taking folic acid with food, splitting the dose across the day, or drinking enough water can often help ease discomfort.

If your stomach problems continue or become painful, it’s a good idea to check in with your doctor. They can help figure out if the supplement is the cause and suggest ways to make you feel better.

Folic acid tablets are important nutrients for overall health, especially during pregnancy. Most people can take it safely, though some might notice mild effects like nausea or indigestion. Severe allergic reactions are rare, but if they do happen, they require immediate medical attention.

If you experience any unusual or unexpected side effects, talk to your healthcare provider, particularly if you are pregnant or planning to become pregnant. When used correctly, folic acid can be a safe and beneficial part of your health routine.

 

References

1. NHS. (2023). Vitamins and minerals – Folic acid. Retrieved from https://www.nhs.uk/conditions/vitamins-and-minerals/folic-acid/
   
2. National Institutes of Health (NIH). (2021). Folate fact sheet for health professionals. Office of Dietary Supplements. Retrieved from https://ods.od.nih.gov/factsheets/Folate-HealthProfessional/
   
3. Mayo Clinic. (2022). Folic acid (oral route) side effects. Retrieved from https://www.mayoclinic.org/drugs-supplements/folic-acid-oral-route/side-effects/drg-20073253
   
4. MedlinePlus. (2023). Folic acid. U.S. National Library of Medicine. Retrieved from https://medlineplus.gov/druginfo/meds/a682333.html
   
5. American Pregnancy Association. (2023). Morning sickness. Retrieved from https://americanpregnancy.org/healthy-pregnancy/pregnancy-health-wellness/morning-sickness/
   
6. NHS. (2023). Morning sickness in pregnancy. Retrieved from https://www.nhs.uk/pregnancy/related-conditions/common-symptoms/morning-sickness/
7. National Institutes of Health (NIH). (2022). Micronutrients and menstrual health. Retrieved from https://ods.od.nih.gov/
8. Office on Women’s Health (OWH). (2021). Menstrual cycle: What is normal? U.S. Department of Health & Human Services. Retrieved from https://www.womenshealth.gov/menstrual-cycle/your-menstrual-cycle
   
9. Great Britain Nutrition and Health Claims Register. (2024). Authorised nutrition and health claims. Retrieved from https://www.gov.uk/government/publications/nutrition-and-health-claims-great-britain-register
   
10. Cleveland Clinic. (2022). Folic acid: Uses, benefits & side effects. Retrieved from https://my.clevelandclinic.org/health/drugs/22536-folic-acid