The most common way of preventing pregnancy is by taking birth control pills or oral contraceptive pills. The combination of progestin and estrogen in these pills makes them more effective. Both progestin and estrogen are female sex hormones which work together to prevent ovulation or the release of eggs from the ovaries. They help in changing the uterus lining to prevent pregnancy. They also help to stop the sperm from entering the body by changing the mucus at the cervix. Though the pills are highly effective form of birth control, they do not provide any protection against the spread of HIV, the virus which causes AIDS and other sexually transmitted diseases. Certain birth control pills also help in treating acne.

Yaz is an example of oral contraceptive pills which helps in treating premenstrual dysphonic disorder in women who are using it. These pills are also very effective in treating irregular or heavy menstruation and endometriosis in which a particular type of tissue which forms the uterus lining tends to grow in other parts of the body causing pain and irregular menstruation. One should be very careful while using these pills because overdose of the same can cause nausea and vaginal bleeding. Some common side effects of these pills are vomiting, diarrhea, weight gain or loss, painful periods, enlargement or tenderness of breast, white vaginal discharge and etc.