Birth Control Pill
How effective is it?
Of 100 women who use this method each year, about nine women may get pregnant on the combined pills and five will get pregnant on the mini-pills. The risk of pregnancy is much less for women who take the pill correctly—every day at about the same time. Certain medications such as Rifampin (taken to treat tuberculosis) and supplements (such as St. John’s Wort) may make the pill less effective.
Advantages of the pill
- The pill is easy to use.
- Birth control pills are safe and work well in preventing pregnancy. Using the pill means you don’t have to think about birth control when you want to have sex.
- Combination pills may offer other benefits such as fewer menstrual cramps, decreased menstrual blood loss, less acne, and stronger bones. They also reduce the risk of some cancers that affect reproductive organs.
- Fertility returns to normal when women discontinue use.
How do I get it?
You need a prescription from your healthcare provider. Birth control pills can be purchased at pharmacies or obtained from a health center, including a family planning center. To search for a clinic near you use our Clinic Locator.
Download Birth Control Pill Fact Sheet
Effectiveness in Preventing Pregnancy
- Of 100 women who use this method each year, about nine may get pregnant.
- The risk is lower in women who take birth control pills correctly—every day at about the same time.
- Pills must be taken daily.
Office Visit Required
- Yes, you need a prescription to get birth control pills.
What is the birth control pill?
The birth control pill, also known as oral contraceptives or just “the pill,” is a medication taken daily to prevent pregnancy. Some women take the pill for reasons other than preventing pregnancy.
Combined pills contain two hormones, estrogen and progestin. Hormones are chemicals that control how different parts of your body work. These pills are taken every day and prevent pregnancy by keeping the ovaries from releasing eggs. The pills also cause cervical mucus to thicken and the lining of the uterus to thin. This keeps sperm from meeting with and fertilizing an egg.
Progestin-only pills (or “mini-pills”) contain only one hormone, progestin which causes cervical mucus to thicken and the lining of the uterus to thin. This keeps sperm from reaching the egg. Less often, mini-pills prevent pregnancy by keeping the ovaries from releasing eggs.
How do I use it?
Combined pills are typically packaged as 21 “active” pills that contain hormones. One pill is taken daily for three weeks, followed by one week off. Others are packaged as 28 pills that include 21 “active” pills taken daily, followed by one week of “inactive” reminder pills that don’t contain hormones.
Some newer formulations have increased the number of active pills to 24 and reduced the inactive pills to 4. With all combined pill formulations, protection against pregnancy continues during the week where no active pills are taken.
Some women use combined pills to limit the number of periods they have, or even to prevent them altogether:
- Extended Cycle use involves taking 12 weeks of active pills followed by one week of inactive pills. Women on an extended cycle have three or four periods a year.
- Continuous Use of pills is where a woman takes an active pill every day so she won’t have any periods at all.
Mini-pills come only in packages of 28-day “active” pills. It is important to take mini-pills every day, and to take them at the same time each day. If you’re late taking a mini-pill by more than three hours, you’ll need to use another type of birth control (such as a condom or sponge) to prevent pregnancy, but continue also to take the mini-pill.
All types of birth control pills should be taken exactly as directed by your health care provider, even on days when you don’t have sex.
Drawbacks of the pill
- The pill does not protect against sexually transmitted infections (STIs), including HIV.
- You need to visit a health care provider to get a prescription.
- You must take your pills every day.
- Certain medications such as Rifampin (taken to treat tuberculosis) and supplements (such as St. John’s Wort) may make the pill less effective.
- Combined pills may cause nausea, changes in your menstrual cycle, breast tenderness or headaches. Discuss your medical history with your health care provider before using any birth control pill, and let them know if you develop any side effects.
- It is uncommon, but some women develop high blood pressure.
- Rarely, use of the combined pill increases the risk of blood clots, heart attack, and stroke. The risk of blood clots increases for very overweight women who use the combined pill.
Centers for Disease Control and Prevention
- Unintended Pregnancy Prevention: Contraception
- United States Medical Eligibility Criteria for Contraceptive Use, 2010
"Contraceptive Technology," Robert A. Hatcher, MD, MPH et. al., 20th revised edition, Contraceptive Technology Communications Inc., 2011.
Food and Drug Administration
Office on Women's Health
Content last reviewed on August 16, 2016