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Contraception health centre

Contraceptive injections

Contraceptive injections are an alternative to other hormonal contraceptive, such as the Pill. They have the advantage of lasting for some weeks rather than having to take a daily tablet.

There are 3 contraceptive injections available - Depo-Provera, Noristerat and Sayana Press.

These contraceptive injections are made up of a hormone similar to progesterone and are given as an injection by a doctor or nurse into a muscle in the woman's arm or buttock.

Depo-Provera injection provides protection against pregnancy for up to 12 weeks, Noristerat injection is effective for up to eight weeks, and Sayana Press injection is effective for 13 weeks. The injections must be given on time to stay protected against pregnancy.

How soon do the injections work?

Contraception with injections begins immediately if given during the first five days of your menstrual period. If given on any other day of the cycle then it only becomes effective after seven days.

How effective are the injections?

They are over 99% effective in preventing pregnancy. However, they do not prevent the spread of STIs. To help protect yourself from STIs, use a male condom each time you and your partner have sex if either one of you could have an STI.

Can any woman use the injections?

Most women can use contraceptive injections, however, they may not be recommended for women who may already be pregnant or are planning a pregnancy within a year, don't want their period cycle to change, or who have:

  • Had breast cancer in the last five years
  • Unexplained vaginal bleeding
  • Arterial disease, heart disease or stroke
  • Diabetes with complications 
  • Liver disease
  • Osteoporosis risk factors
  • Lupus.

Are there side effects associated with the injections?

Possible side effects include:

Most of the side effects are not common. Change in the menstrual cycle is the most common side effect. You may experience irregular bleeding or spotting. Some women find that their periods stop altogether. Their periods usually return when they discontinue the injections.

Prolonged use of Depo-Provera may result in significant loss of bone mineral density, increasing the risk of osteoporosis. This risk is more likely for those who have been taking it for longer than two years, particularly when other risk factors for osteoporosis exist, such as family history of osteoporosis and long-term alcohol and/or tobacco use. Although there are no studies to show benefit, it is advised that all women on Depo-Provera get adequate calcium and vitamin D (through diet and/or supplements) to help prevent osteoporosis.

Can I become pregnant after I stop taking the injections?

With contraceptive injections a woman could become pregnant before her first period after stopping using the contraceptive injection. However, it may take some women up to a year or two to conceive after they stop using this type of contraception.

WebMD Medical Reference

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