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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.

These contraceptive injections are made up of a hormone similar to progesterone. Depo-Provera and Noristerat are given as an injection into a muscle, usually in the woman's buttock, whilst Sayana Press in given by injection under the skin, usually in the abdomen or front of the thigh.

Depo-Provera and Sayana Press provide protection against pregnancy for up to 13 weeks, Noristerat injection is effective for up to eight 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:

Are there side effects associated with the injections?

Possible side effects include:

  • Irregular menstrual periods, or no periods at all
  • Headaches
  • Nervousness
  • Depression
  • Dizziness
  • Acne
  • Changes in appetite
  • Weight gain
  • Excessive growth of facial and body hair
  • Hair loss
  • Loss of bone mineral density

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 and Sayana Press 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.

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.

What are the advantages of using the contraceptive injection?

  • You don't have to remember to take it every day or use it before sex.
  • It provides long-term protection as long as you get the injection as often as recommended.
  • It doesn't interfere with sexual activity.
  • It's over 99% effective.
  • It is not affected by other medications.

What are the disadvantages of using the contraceptive injection?

  • It can cause unwanted side effects, which will last for the duration of the injection.
  • It does not provide protection against sexually transmitted infections.
  • It can cause irregular menstrual periods.
  • There can be a delay of up to a year before the return of periods and fertility.
  • Regular GP or clinic visits can be inconvenient, although after training, Sayana Press can be self-injected at home.

WebMD Medical Reference

Medically Reviewed by Dr Rob Hicks on July 12, 2017

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