Folic Acid Side Effects — Can You Get Too Much?

2. Supplement Side Effects

Folic acid, like most supplements, can cause side effects for some people. Most potential side effects are fairly mild, such as a bitter aftertaste, nausea, vomiting, loss of appetite, diarrhea, or stomach gas. These could be due to the body getting used to the supplement. More serious side effects include confusion, irritability, and sleep disruptions. Chest pain, difficulty breathing, or a skin rash may indicate a potentially life-threatening reaction and require immediate medical attention.