Abiraterone acetate is a prescription medication used to treat prostate cancer. It is a type of hormone therapy known as an androgen biosynthesis inhibitor, which works by blocking the production of male hormones in the body, especially testosterone. Abiraterone acetate comes in the form of a capsule taken by mouth once a day. It is usually prescribed in combination with prednisone, a type of steroid medication. Common side effects of abiraterone acetate include fatigue, high blood pressure, joint pain, and hot flashes.