The Contraceptive Injection

An injectable option of contraception that contains the hormone progestogen, more than 99% effective when used perfectly.

 Key points:

  • Depending on the type of injection you receive, the contraceptive effect lasts for 8 to 13 weeks.
  • Very useful contraception method for women who struggle to remember to take their oral contraceptives daily.
  • Suitable for women who could not tolerate oestrogen in their choice of contraceptive.
  • The contraceptive injections do not prevent sexually transmitted infections (STIs), a barrier method is still needed, e.g. condoms.

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Is it just another female contraceptive method?

Contraceptive methods have evolved and revolutionised over the years, however, the mechanism of action remains the same, that is through the release of hormones similar to those produced by the ovaries to achieve contraception. 

The contraceptive injections release progestogen into your bloodstream over a period of time, tricking the body into thinking you are already pregnant. In turn, the release of an egg (ovulation) is delayed or prevented, the uterus lining becomes thinner so a fertilised egg is less likely to implant successfully, and the cervical mucus also thickens making it more difficult for sperm to get through the cervix. 

The need to develop new methods is to improve both efficacy and compliance. Until this day, especially with busier lifestyles, many users forget to take or use them properly thus resulting in a failure of these methods for them.

Long-acting reversible contraception (LARC) has significantly increased in popularity because users do not have to remember to use it every day for effective contraception. Currently, there are four types of LARC available.

  1. The contraceptive implant, e.g. Nexplanon
  2. Intrauterine device (IUD), e.g. copper IUD
  3. Intrauterine system (IUS), e.g. Mirena, Jaydess
  4. Contraceptive injection, e.g. Depo-Provera, Sayana Press, Noristerat

See our wide selection of contraceptive pill brands online

Why should I consider contraceptive injections?

Depo-Provera and Noristerat are administered intramuscularly, usually given at the buttocks, but Depo-Provera can also be given in the upper arm muscle. Sayana Press, on the other hand, is administered subcutaneously, just under the skin, usually into the front of the thigh or into the abdomen.

Like all contraception methods, contraceptive injections come with their own advantages and disadvantages.


  • Each injection lasts either 8 weeks (Noristerat) or 13 weeks (Depo-Provera and Sayana Press), depending on the product. During which time you do not have to think about contraception.
  • Contains only progestogen hormone, therefore suitable for those who could not tolerate oestrogen-containing contraception.
  • Comes in liquid form to be injected, and does not need to be removed before the next injection is due.
  • It does not interrupt sex.
  • It is safe to use while breastfeeding.
  • It is not known to interact with other medicines you may be taking.
  • The option to self administer (only with Sayana Press) after basic injection technique training, instead of having to attend the clinic frequently.
  • For some women, it improves their premenstrual symptoms, regulates their heavy and painful periods.


  • Once injected, it stays in your body for 8 or 13 weeks and can not be removed. If you experience any side effects, these may last throughout this duration or longer afterwards.
  • It does not provide protection against sexually transmitted infections (STIs), barrier methods like condoms are still necessary.
  • It could take up to a year or longer for your fertility to return to normal.
  • If you are a user of Depo-Provera or Noristerat, you will need regular appointments with a trained healthcare professional to administer the injections.
  • For some women, there have been reports of irregular, heavy, longer, shorter periods or no period altogether. This could continue for some time after stopping the injection.
  • You may experience weight gain with Depo-Provera or Sayana Press.
  • You may experience some side effects such as headaches, hair loss, abdominal discomfort, acne, mood swings, and lower sex drive.

While you weigh up the pros and cons, it is also worth noting there are certain groups of women in which the contraceptive injection method may not be suitable for,

  • Women who are or may already be pregnant
  • Women who plan to become pregnant in the next year
  • Women who have unexplained bleeding between periods or after sexual intercourse
  • Women who do not want their periods to be affected
  • Women who are allergic to the ingredients of the injection
  • Women who have or had breast cancer
  • Women with arterial diseases, or a history of heart disease or stroke
  • Women who have or are at risk of osteoporosis, including known family history
  • Women who have liver disease

Most women can have the injections, but it is also advisable that you seek advice from your GP, pharmacist, or sexual health clinic healthcare professional, especially if you take long term regular medication.

How long does it take to start working?

 Following a negative pregnancy test, you can have the injection at any point in your menstrual cycle. If this is done within the first 5 days of your menstrual cycle, you will be immediately protected against pregnancy. On any day outside of the first 5 days, you will need additional protection, such as a condom, for seven days following the injection.

The contraceptive injection is safe to use after childbirth and when breastfeeding. If you receive the injection within 21 days of childbirth, you will receive immediate protection against pregnancy, whereas outside of the 21 days, you will need to use additional contraception for the next seven days. Starting the injections within the first few weeks since giving birth is more likely to cause heavy or irregular bleeding.

For breastfeeding women, you should wait at least 6 weeks from childbirth before starting the injections. The injections are not known to be harmful or affect your milk supply.

The contraceptive injections can also be used after a miscarriage or abortion. If you start the injections immediately you will be protected straight away. If the injections are started 5 days or more afterwards, you will need additional contraception, such as a condom, for the next seven days.

If you are considering switching from another form of contraception, you should discuss with your healthcare professional about it to ensure continuous coverage of contraception. For example, if you are switching over from an oral contraceptive, and are taking the pill as instructed, you should receive your first injection within 7 days of taking your last active pill.

Where can I get the injections?

Contraception is offered for free across the UK to females of child-bearing age, including females under 16 years of age. You may visit:

  • Your GP surgery
  • Sexual health and genitourinary (GUM) clinic
  • Contraception clinics
  • Some young people’s services

Find your nearest sexual health service provider using this link.