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Birth Control Shot

Medically reviewed by: Lonna P. Gordon, MD

What Is the Birth Control Shot?Birth Control Shot

The birth control shot is an injection given to a girl every 3 months to help prevent pregnancy. The birth control shot contains a longer acting form of the hormone progestin.

How Does the Birth Control Shot Work?

The hormone progestin in the birth control shot works by preventing ovulation (the release of an egg during the monthly menstrual cycle). If an egg isn't released, pregnancy can't happen because there's no egg for the sperm to fertilize.

The progestin also thickens the mucus around the cervix. This makes it hard for sperm to enter the uterus and reach any eggs that may have been released. The progestin also thins the lining of the uterus so that an egg will have a hard time attaching to the wall of the uterus.

How Well Does the Birth Control Shot Work to Prevent Pregnancy?

The birth control shot is an effective birth control method. Over the course of a year, about 6 out of 100 typical couples who use the birth control shot will have an accidental pregnancy. The chance of getting pregnant increases if a girl waits longer than 3 months to get her next shot.

In general, how well each type of birth control method works depends on a lot of things. These include whether a person has any health conditions or is taking any medicines that might affect its use. It also depends on whether the method is convenient and whether the person remembers to use it correctly all of the time.

Does the Birth Control Shot Help Prevent STDs?

No. The birth control shot does not protect against STDs. Couples having sex must always use condoms along with the shot to protect against STDs.

Are There Any Side Effects With the Birth Control Shot?

The birth control shot often causes period changes. Side effects can include:

  • irregular periods or no menstrual periods
  • weight gain, headaches, and breast tenderness
  • depression

The U.S. Food and Drug Administration (FDA) has issued a safety warning about the use of the birth control shot. Studies link this shot to a loss of bone density, although bone density may recover when someone stops getting the shot. The loss of bone density seems to be worse when the shot is used for longer periods of time.

Doctors are not sure how this type of shot may affect the bone density of young people in the future, though. Anyone considering the shot should talk to their doctors about it and make sure that they get enough calcium each day. Those who smoke should be sure to let their doctors know because smoking may be connected to this bone density loss.

Some people receiving shots may notice their periods are irregular for up to a year after stopping the shot. But the shot does not cause permanent loss of fertility and most users can get pregnant after they stop getting the shot.

Who Can Use the Birth Control Shot?

Anyone who has trouble remembering to take birth control pills and who wants extremely good protection against pregnancy may want to use the birth control shot. Also, nursing mothers can use the birth control shot.

Some medical conditions make the use of the shot less effective or riskier. For example, it is not recommended anyone who has had blood clots, some types of cancers, or liver disease. Those who have had unexplained vaginal bleeding (bleeding that is not during their periods) or who might be pregnant should not get the birth control shot and should talk to their doctors.

Where Is the Birth Control Shot Available?

The shot must be prescribed and is given every 3 months in a doctor's office or family planning clinic.

How Much Does the Birth Control Shot Cost?

Each injection (3 months' worth of birth control) costs between $0 and about $150. Many health insurance plans cover the cost of birth control shots, as well as the cost of the doctor's visit. Family planning clinics (such as Planned Parenthood) may charge less.

When Should I Call the Doctor?

If you use the birth control shot, call your doctor if you:

  • might be pregnant
  • have a change in the smell or color of your vaginal discharge
  • have unexplained fever or chills
  • have belly or pelvic pain
  • have pain during sex
  • have heavy or long-lasting vaginal bleeding
  • have yellowing of the skin or eyes
  • have severe headaches
  • feels depressed
  • have signs of a blood clot, such as lower leg pain, chest pain, trouble breathing, weakness, tingling, trouble speaking, or vision problems
Medically reviewed by: Lonna P. Gordon, MD
Date reviewed: January 2022