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Birth Control Pill Fact Sheet

How effective is it?

Of 100 women who use this method each year, about 5 women are likely to get pregnant. The risk of pregnancy is much less for women who take the pill correctly (every day at about the same time). The pill may be less effective in women who are very overweight. Talk with your health care provider if you have any questions about birth control pills.

Advantages of the pill

  • The pill is easy to use and doesn't require that you ask a male partner.

  • 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 that include fewer menstrual cramps, less acne, and stronger bones. They can also reduce the risk of some cancers that affect reproductive organs.

How do I get it?

You need a prescription. Birth control pills can be purchased at pharmacies and clinics. To search for a family planning clinic near you use our Clinic Locator.

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Quick Facts

Effectiveness in Preventing Pregnancy

  • About 5 women out of 100 using this method for one year will get pregnant.
  • The risk is lower in women who take birth control pills correctly.


  • Pills must be taken daily.

STI Protection

  • No

Clinic 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 medicine 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 work by causing the cervical mucus to thicken, which blocks sperm from meeting with and fertilizing an egg.

Progestin-only pills (or "mini-pills") contain only one hormone, progestin. These pills work mainly by causing the cervical mucus to thicken, which prevents sperm from reaching an egg. Less often, mini-pills prevent pregnancy by stopping 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.  With either the 21- or 28-day pills, 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 daily so she won't have any periods

Mini-pills come only in packages of 28-day "active" pills. It is important not only to take mini-pills everyday, but 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. 

With either type of birth control pill, take them 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).
  • You need to visit a clinic to get a prescription.
  • You must take your pills every day.
  • Certain antibiotics and supplements (such as St. John's Wort) may make birth control pills less effective.
  • If you stop the pill, it may take a month or two before normal periods return.
  • Combined pills may cause dizziness, nausea, mood swings, and weight gain (these side effects often go away in a few weeks or months). 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.
  • Rarely, use of the combined pill increases the risk of blood clots, heart attack, and stroke.



Office on Women's Health:

Centers for Disease Control and Prevention

Food and Drug Administration