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The Birth Control Shot

What Is the 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 long 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 cycle). If a girl doesn't ovulate, she cannot get pregnant because there is no egg to be fertilized.

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?

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. In fact, some studies show that the birth control shot may possibly increase the risk of getting some STDs, although scientists do not understand why.

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?

Many girls who use the birth control shot will notice a change in their periods. Side effects that some girls have 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 in women, although bone density may recover when a woman is no longer 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 teen girls in the future, though. Girls who are 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.

Women may notice a decrease in fertility for up to a year after they stop getting the birth control shot. However, the shot does not cause permanent loss of fertility and most women can get pregnant after they stop getting the shot.

Who Can Use the Birth Control Shot?

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

Not all girls can — or should — use the birth control shot. Some medical conditions make the use of the shot less effective or more risky. For example, it is not recommended for girls who have had blood clots, some types of cancers, or liver disease. Girls 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?

Someone using the birth control shot should call the doctor if she:

  • might be pregnant
  • has a change in the smell or color of vaginal discharge
  • has unexplained fever or chills
  • has belly or pelvic pain
  • has pain during sex
  • has heavy or long-lasting vaginal bleeding
  • has yellowing of the skin or eyes
  • has severe headaches
  • feels depressed
  • has signs of a blood clot, such as lower leg pain, chest pain, trouble breathing, weakness, tingling, trouble speaking, or vision problems
Reviewed by: Larissa Hirsch, MD
Date reviewed: August 2018