Birth control pills use hormones to prevent pregnancy. The female hormones in the pills change a woman's natural hormone levels and prevent her ovaries from releasing an egg each month. The hormones also help prevent pregnancy in 2 other ways: They cause a thickening of the mucus on the cervix and they change the lining of the uterus. The thickened mucus on the cervix makes it hard for sperm to enter the uterus to fertilize any egg that might have escaped from the ovary. The change in the lining of the uterus helps prevent an egg from attaching to the uterus if an egg did escape and was fertilized.
The most commonly used pills contain man-made forms of 2 female hormones: estrogen and progesterone. There is also a progesterone-only pill (the mini-pill), but it is not as effective and you are more likely to have bleeding between menstrual periods.
Another name for birth control pills is oral contraceptives.
The pills that contain both hormones usually come in a package of 28 pills. They are also available in 21-pill or 91-pill packs. You and your healthcare provider will decide which type of package is best for you. Your provider will probably advise you to start taking the pills on the Sunday after your period has started or on the first day of your next period, depending on your preference.
21-day pill pack
If you are using the 21-pill pack, take 1 pill every day for 3 weeks. Stop taking the pills for 7 days and then start a new pack. Your period will start during the week that you are not taking pills.
28-day pill pack
If you are using the 28-day package, take 1 pill every day for 4 weeks and then start a new package the next day. The last 7 pills in the pack are inactive, which means that they do not contain medicine for birth control. They just keep you in the habit of taking a pill every day. Your period will start during the week that you are taking the last 7 pills that have no hormone medicine in them.
91-day pill pack
If you are using the 91-day pill pack, you take 1 pill of active medicine every day for 12 weeks (84 days). Then you take 1 inactive pill every day for 7 days. You will have your period while you are taking the inactive pills. This means that you will have a period just once every 3 months.
If you miss taking a pill, you may get pregnant.
If you forget 1 pill, take it the scheduled day as soon as you remember. If you don’t remember until the next day, take 2 pills that day. Then go back to your regular schedule and take the next pill on time. You may have some spotting from missing the pill.
If you miss 2 or more pills in a row, see the information sheet that comes in the medicine package or ask your healthcare provider what to do. Use another method of birth control, such as condoms, until your next period starts.
The benefits are:
One disadvantage of birth control pills is that you must remember to take a pill every day.
The pills are generally considered safe, but sometimes they cause side effects, such as:
You should not smoke. Smoking increases the risk of serious side effects, such as heart attack, stroke, and blood clots. This is especially true if you are over 35 years old and smoke.
Other rare risks of taking birth control pills include cataracts, gallstones, and noncancerous liver tumors.
Although some of these possible side effects may seem concerning, keep in mind that most women have no problems when taking birth control pills.
Birth control pills do not protect you from sexually transmitted diseases such as AIDS. Latex or polyurethane condoms are the only safe way to protect against the HIV virus and AIDS.
Some medicines can change the way birth control pills work in your body. Birth control pills may not keep protecting you against pregnancy if you are taking certain antibiotics or medicines for seizures or fungal infections. Tell your healthcare provider about all medicines or natural remedies you are taking. You may need to use an additional form of birth control while you are taking these medicines.
Call your provider right away if you have any of the following symptoms:
Call during office hours if: