Overview & Description

Progestin injections are shots of a type of progestin that is given to women for birth control. Medroxyprogesterone acetate is the progestin used in these shots. It is similar to the female hormone progesterone that the body naturally produces.

Who is a candidate for the procedure?

Progestin injections are often used as birth control, to prevent pregnancy. They are also used to control heavy or irregular menstrual bleeding. Progestin injections also decrease a woman's risk for uterine cancer.

Progestin injections prevent pregnancy in these ways:

How is the procedure performed?

Progestin injections are generally given in the muscle of the buttocks or upper arm. A single shot provides birth control for 12 weeks. It can be repeated if the woman wishes to continue birth control. It is very important for a woman to get these shots exactly every 12 weeks. The shots are less effective in preventing pregnancy if the time between shots is more than 12 weeks. Shots may be given more often if they are used for heavy or abnormal menstrual bleeding.

Preparation & Expectations

What happens right after the procedure?

A woman can go home and return to normal activities right after the injection.

Home Care and Complications

What happens later at home?

Over-the-counter pain medicines, such as acetaminophen or ibuprofen, can be used as needed for pain or swelling.

What are the potential complications after the procedure?

There is less chance of getting pregnant with progestin injections than with oral contraceptives, or birth control pills. This is mainly because a woman does not need to remember to take a pill every day.

Unfortunately, many women develop irregular vaginal bleeding. They may not have one period every month. They may have multiple episodes each month of bleeding for several days. Sometimes a woman's period may last longer than it did before beginning the shots. Other women may find that their periods are shorter than before. These problems may cause a woman to want to stop using the injections for birth control. Many women will stop having periods within a year of using this form of birth control. Some of the other possible side effects are as follows:

Progestin injections decrease a woman's bone mass and may put her at risk for osteoporosis. Bone loss tends to be greatest during the first few years of use. It then drops to a rate of bone loss similar to that of women of the same age. The effects on bone density are reversible once the injections are stopped.

Using progestin injections may slightly increase the risk of breast cancer. Some research has shown no increase in risk. Other studies have shown a small increase in risk. Once a woman stops the progestin injections, her overall chances of becoming pregnant are not different from women who never used the injections. However, a woman who has used the injections may take a longer time to become pregnant.