The birth control shot, also known by its brand name Depo-Provera, is a hormonal method of birth control. Approved by the Food and Drug Administration (FDA) in 1992, Depo-Provera has been used (or at least tried) by 22 percent of women in the U.S., according to the U.S. Centers for Disease Control and Prevention.

What Is It?

The birth control shot is an injection of the hormone progestin, which prevents pregnancy for up to three months.

How Does It Work?

The birth control shot contains a synthetic hormone called progestin, which essentially blocks ovulation (the release of an egg in the ovaries). Without ovulation, pregnancy cannot occur because there is no egg for the sperm to fertilize. Progestin also thickens the cervical mucus to block sperm and weakens the lining of the uterus to prevent implantation of the egg. Each birth control shot has enough hormones to prevent pregnancy for up to three months.

How Do I Use it?

You need a prescription to get the birth control shot. Make an appointment with your doctor to discuss what method of birth control is best for you. A doctor will administer the shot during your exam, usually at the start of your menstrual period. You will need to return to the doctor’s office every three months for an injection. The birth control shot is typically given in the upper arm or buttocks.

Effectiveness

The Depo-Provera shot is one of the most effective birth control methods, preventing pregnancy in more than 99 percent of cases.

Benefits

The primary benefit of the birth control shot is its simplicity. Get a shot every three months and you don’t have to worry about birth control every day or before sex. The shot also provides a level of privacy not available with other birth control methods. There is no evidence of birth control on your body or any supplies or packaging to carry around. Because the birth control shot only contains the hormone progestin, it is a good option for women who cannot take estrogen. This is also considered a good option for teenagers who are less likely to be compliant with a daily birth-control-pill regimen and may not want to have a visible implant or patch.

Disadvantages

The birth control shot does not protect against sexually transmitted diseases. Research has found that the use of Depo-Provera may cause a temporary loss of some of the calcium stored in your bones, which can lead to osteoporosis. Doctors recommend only using Depo-Provera long-term (for more than two years) if other birth control methods do not work for you. Some women experience minor side effects from the birth control shot, including irregular bleeding, change in sex drive, weight gain, nausea, and sore breasts.