Folic Acid for Fibromyalgia & Chronic Fatigue Syndrome

You might associate folic acid with pregnancy, since it’s commonly recommended for preventing birth defects. Folic acid does a lot more than that, though, and it’s even gotten attention as a potential treatment for fibromyalgia and chronic fatigue syndrome.

Folic acid is also called vitamin B9 or folate. It plays a role in:

  • Turning food into fuel
  • Using fats and protein
  • Keeping hair, skin, and eyes healthy
  • Brain/nerve function
  • Liver health
  • Heart health,
  • Cancer prevention
  • Production of genetic material
  • Making iron and red blood cells work properly

Some studies suggest that folic acid may help alleviate depression; however, results are mixed.

Folic Acid Deficiency

Folic acid and vitamin B12 work closely together in many of these functions, and therefore it’s often recommended that they are taken together.

Low folic acid levels are somewhat common. A true deficiency, however, is rare. Deficiency can lead to:

  • Mental sluggishness
  • Forgetfulness
  • Irritability
  • Anemia (low red blood cell count)
  • Nerve problems in the limbs
  • Diarrhea,
  • Loss of appetite
  • Poor growth

Role in Treating Fibromyalgia and CFS

We don’t have a lot of research on folic acid for fibromyalgia and chronic fatigue syndrome. Studies done back in the 1980s and ’90s produced mixed results, but more recent ones have suggested that it may play a positive role in our treatment.

An uncontrolled study (Lundell, 2006) provided preliminary evidence that folic acid supplementation might improve symptoms in people with chronic fatigue syndrome, especially those with B-cell immunodeficiency and reactivated Epstein-Barr virus infection. However, this result has not been replicated.

A 2015 study (Regland) supported the use of folic acid and B12 supplementation in chronic fatigue syndrome, especially in those with comorbid fibromyalgia. Researchers concluded that higher dosages led to better response, especially in those with both conditions. However, those regularly taking opiate painkillersCymbalta (duloxetine), or Lyrica (pregabalin) on a daily basis reported a lesser effect. That led researchers to suspect a negative interaction between the drugs and supplements.

It’s common to see nutritionists and natural healers suggest folic acid as a treatment for fibromyalgia and chronic fatigue syndrome as well.

Dietary Sources

Folic acid is readily available in foods. Common dietary sources include:

  • Asparagus
  • Avocado
  • Beef liver
  • Beets
  • Brussel sprouts
  • Kidney, lima, white and mung beans
  • Milk
  • Orange juice
  • Root vegetables
  • Salmon
  • Spinach and other dark leafy greens
  • Wheat germ
  • Whole grains

In the United States, all grain and cereal products are fortified with folic acid.


If you choose to take folic acid supplements, first check on whether you’re already getting it in a multivitamin or B-vitamin complex.

In adults, the recommended daily allowance of folic acid is 400 mcg. (Higher doses are suggested for pregnant and breastfeeding women.)

It’s often recommended that you take a B-complex supplement because long-term supplementation with one of the B vitamins may lead to imbalances in the others. Also, folic acid supplements may mask symptoms of a dangerous B12 deficiency.

Side Effects

Any supplement you take has the potential to cause unwanted side effects. Side effects from folic acid are rare at the recommended daily allowance. High doses may lead to:

  • Confusion
  • Loss of appetite
  • Nausea
  • Seizures
  • Skin reactions
  • Sleep problems
  • Stomach problems

The following medications may interact negatively with folic acid:

  • Antibiotics
  • Dilantin (phenytoin)
  • Daraprim (pyrimethamine)
  • Chemotherapy medications

Many drugs can interfere with folic acid levels or absorption rates, including some that are common for those of us with fibromyalgia and chronic fatigue syndrome. Those include:

  • Anti-inflammatories (NSAIDs) such as Aleve (naproxen) or Advil/Motrin (ibuprofen)
  • Azulfidine (sulfasalazine) for rheumatoid arthritis or inflammatory bowel disease
  • Acid blockers, including antacids, H2 blockers (cimetidine, famotidine, ranitidine), and proton pump inhibitors (lansoprazole, omeprazole, rabeprazole)

Your doctor can help you identify any potential interactions and the pinpoint the correct dosage for you. It’s also never a bad idea to check with your pharmacist about interactions—they may be aware of some that your doctor is not.

More Supplement Information

To learn more about taking supplements for fibromyalgia and chronic fatigue syndrome, see:

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