Get emergency medical help if you have signs of an allergic reaction to folic acid: hives, rash, itching, skin redness; wheezing, difficult breathing; swelling of your face, lips, tongue, or throat.
Common folic acid side effects may include:
nausea, loss of appetite;
bloating, gas, stomach pain;
bitter or unpleasant taste in your mouth;
confusion, trouble concentrating;
sleep problems;
depression; or
feeling excited or irritable.
This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.
 Folic acid side effects (more detail)
