Breast tenderness and enlargement, bloating, headaches, and nausea are some of the common side effects of birth control pills. In most cases, side effects are merely bothersome and are usually not dangerous. Some birth control pill side effects, however, are potentially serious and should be reported to a healthcare provider, including chest pain, breast lumps, or high blood pressure.
(Click Side Effects of Birth Control Pills for a more in-depth look at side effects associated with this form of contraception, including potentially serious problems that may require immediate medical attention.)