What are the side effects of taking folic acid?

Folic acid is a substance well known to many expectant mothers. Also called vitamin B9, it is a water-soluble vitamin. Women who are planning pregnancy or are already pregnant require appropriate folic acid supplementation—not only for their own health but also for the healthy development of their fetus. However, folic acid should be taken only under medical supervision; otherwise, certain side effects may occur. So, what are the potential side effects of folic acid? Below, we address this question.

What Are the Side Effects of Folic Acid?

Generally, folic acid is well tolerated and rarely causes side effects when taken at recommended doses. However, excessive intake may lead to toxicity in the body. Long-term consumption of high-dose folic acid may cause gastrointestinal symptoms such as loss of appetite, abdominal distension, and dark yellow urine. Excessive folic acid intake during pregnancy may adversely affect the child’s future neurological development or increase susceptibility to psychiatric disorders. Currently, women before and during pregnancy are generally advised to take 400 micrograms (mcg) daily; however, specific dosage recommendations should always follow the instructions provided with individual folic acid supplements. Women of childbearing age should begin daily folic acid supplementation (400 mcg) three months prior to conception and continue throughout pregnancy. This is because folic acid levels in the body do not rise significantly within a short period after initiating supplementation.

Knowledge Expansion: Benefits and Functions of Folic Acid

1. Reduces Risk of Neural Tube Defects (NTDs)

Neural tube defects (NTDs) are congenital malformations with a notably high incidence in China. Therefore, women should ensure adequate folic acid intake during pregnancy. Folic acid promotes proper neural tube development in the fetus, supporting complete structural formation and effectively preventing NTDs—thereby helping women deliver healthier, more cognitively developed babies.

2. Prevents Cardiovascular Disease

Folic acid is not exclusively beneficial for women or pregnant individuals; middle-aged and older adults may also benefit from appropriate folic acid supplementation. This nutrient acts directly on the cardiovascular system—helping regulate blood pressure and lipid levels, dilating coronary arteries, improving circulation, and significantly reducing the incidence of atherosclerosis, coronary heart disease, and other cardiac conditions.

The above outlines the potential side effects associated with folic acid supplementation. We hope this information is helpful to you.