Oral contraceptives use hormones to prevent pregnancy. Combination pills contain both progestin and estrogen.

The pill - combination; Oral contraceptives - combination; OCP - combination; Contraception - combination; BCP - combination

Birth control pills help keep you from getting pregnant. When taken daily or as prescribed, they are one of the most effective methods of contraception. For most women they are extremely safe. They also have a number of other benefits. Some of these include:

• Improve painful, heavy, or irregular periods
• Treat acne
• Reduce the chance of developing ovarian cancer

Combination birth control pills contain both estrogen and progestin. Some combination birth control pills allow you to have fewer periods each year. These are called continuous or extended-cycle pills. Ask your health care provider about dosing options to decrease the frequency of your menstrual cycles.

Birth control pills come in packages. You take pills from a 21-pack once a day for 3 weeks, then you do not take pills for 1 week. It may be easier to remember to take 1 pill every day, so other pills come in a 28-pack of pills, with some having active pills (containing hormones) and some with no hormones.

There are 5 types of combination birth control pills. Your provider will help you choose the right one for you. The 5 types are:

• One phase pills: These have the same amount of estrogen and progestin in all the active pills.
• Two phase pills: The level of hormones in these pills changes once during each menstrual cycle.
• Three phase pills: Every 7 days the dose of hormones changes.
• Four phase pills: The dose of hormones in these pills changes 4 times each cycle.
• Continuous or extended cycle pills: These keep the level of hormones up so you have few or no periods.

You may:

• Take your first pill on the first day of your period.
• Take your first pill on the Sunday after your period starts. If you do this, you need to use another birth control method (condom, diaphragm, or sponge) for the next 7 days. This is called backup birth control.
• Take your first pill any day in your cycle, but you will need to use another birth control method for the first month.

For continuous or extended cycle pills: Take 1 pill every day, at the same time each day.

Take 1 pill every day, at the same time of day. Birth control pills only work if you take them every day. If you miss a day, use a backup method.

If you miss 1 or more pills, use a backup method of birth control and call your provider right away. What to do depends on:

• What type of pill you are taking
• Where you are in your cycle
• How many pills you missed

Your provider will help you get back on schedule.

You may decide to stop taking birth control pills because you want to get pregnant or change to another birth control method. Here are some things to expect when you stop taking the pill:

• You might become pregnant right away.
• You may have mild spotting of blood before you get your first period.
• You should get your period 4 to 6 weeks after taking your last pill. If you do not get your period in 8 weeks, call your provider.
• Your period may be heavier or lighter than usual.
• Your acne may return.
• For the first month, you may have headaches or mood swings.

Use a backup method of birth control, such as condom, diaphragm, or sponge if:

• You miss 1 or more pills.
• You are not starting your first pill on the first day of your period.
• You are sick, throwing up, or have loose stools (diarrhea). Even if you take your pill, your body may not absorb it. Use a backup method of birth control for the rest of that cycle.
• You are taking another medicine that may keep the pill from working. Tell your provider or pharmacist if you take any other medicines, such as antibiotics, seizure medicine, medicine to treat HIV, or St. John's wort. Find out if what you take will interfere with how well the pill works.

Contact your provider if you have any of the following symptoms after starting to take the birth control pills:

• You have swelling in your leg
• You have leg pain
• Your leg feels warm to the touch or has changes in skin color
• You have fever or chills
• You are short of breath and it is hard to breathe
• You have chest pain
• You cough up blood
• You have a headache that gets worse, especially a migraine with aura

Allen RH, Kaunitz AM, Hickey M, Brennan A. Hormonal contraception. In: Melmed S, Auchus, RJ, Goldfine AB, Koenig RJ, Rosen CJ, eds. Williams Textbook of Endocrinology. 14th ed. Philadelphia, PA: Elsevier; 2020:chap 18.

Glasier A. Contraception. In: Jameson JL, De Groot LJ, de Kretser DM, et al, eds. Endocrinology: Adult and Pediatric. 7th ed. Philadelphia, PA: Elsevier Saunders; 2016:chap 134.

Isley MM. Postpartum care and long-term health considerations. In: Landon MB, Galan HL, Jauniaux ERM, et al, eds. Gabbe's Obstetrics: Normal and Problem Pregnancies. 8th ed. Philadelphia, PA: Elsevier; 2021:chap 24.