Safety and side effects

When taken by mouth in typical amounts for a short time, evening primrose oil is most likely safe.

But taking evening primrose oil can cause:

• Upset stomach.
• Loose stools.
• Headache.

Don't take evening primrose if you have a bleeding condition. Taking the supplement may raise the bleeding risk. If you're having surgery, stop taking evening primrose two weeks before the surgery.

Also, don't take evening primrose if you have epilepsy or schizophrenia. The supplement might raise your risk of seizures.

Evening primrose oil might raise the risk of pregnancy complications. Some types of evening primrose may act like estrogen. So people with hormone-sensitive cancers also shouldn't take it. It also may raise blood pressure.