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Contraceptive injection

The contraceptive injection contains the hormone progestogen. This is similar to the progesterone naturally produced in women’s ovaries and works to control your fertility.

Here are some key facts:

  • The injection is over 99% effective
  • One injection can protect you from pregnancy for 8, 12 or 13 weeks depending on the type you are using 
  • Depo-Provera is the most commonly used contraceptive injection in the UK
  • The injection is a method of long-acting reversible contraception (or LARC) which don’t rely on you remembering to take them
  • It doesn't protect against sexually transmitted infections (STIs) so you will also need to condoms
  • The injection is not affected by medication that often affects other types of contraception

How does the contraceptive injection work?

Pregnancy happens when sperm reaches an egg and fertlises it. Theinjection works in three ways to interrupt this process:

  • It stops ovulation
  • It thickens the mucus around the cervix, which makes it harder for sperm to get through
  • It makes the lining of the womb thinner so that a fertilised egg cannot implant 

The injection is a method long-acting reversible contraception (or LARC). These methods don’t rely on you remembering to take them, but they do need a trained doctor or nurse to administer or fit them for you.

The most commonly used injection is Depo-Provera (or DMPA). Depo-Provera and Noristerat must be administered by a doctor or nurse. However, there is now an injection called Sayana Press which you can be taught to inject yourself at home.  

The injection is over 99% effective at preventing pregnancy. This means that less than one woman in 100 will get pregnant in a year.


How do I get the contraceptive injection?

You will need to see a doctor or nurse to discuss which of the three injections is most suitable for you. However, Sayana Press (the one you inject yourself) is not available everywhere at the moment. The injection is available free of charge from contraceptive clinics, your GP and Brook. Find your nearest using our find a service tool.

When you go to get the injection, an appointment will typically include:

  • A few questions about your medical and family history, to work out what would suit you best.
  • The doctor or nurse will take your blood pressure and they will weigh you.

You will not be required to have an internal or breast examination for the injection. 

After the injection has been given you only need to go back if you have any problems or when you need a new injection (at either 8, 12 or 13 weeks depending on the type). If you are using the Sayana Press (which you inject yourself at home) you only have to go back to the clinic annually because you will be given a years supply. You can return to the clinic at any time if you are worried about anything.  

Contraception and sexual health services such as Brook are free and confidential, including for people under the age of 16. Health professionals work to strict guidelines and won’t tell anyone else about your visit unless they believe you're at serious risk of immediate harm. Find out more about Brook’s confidentiality policy.

Can you use the contraceptive injection yourself?

Sayana Press has recently been approved for self-administration. This means you inject yourself at home. If you have chosen Sayana Press the nurse or doctor will teach you to inject yourself and also how to dispose of the needle safely. They will also explain to you when the next injection is due (every 13 weeks). You will be given a yearly supply of the injection to use at home.

If you are interested in this method ask at your local clinic. Brook are also in the process of introducing this method.

Starting the contraceptive injection and when you are protected from pregnancy

You can have the injection at any time in your menstrual cycle if you are certain you are not pregnant. If you're given the injection during the first five days of your period you will be protected against pregnancy immediately.

If you have the injection on any other day of your cycle you will not be protected for the first seven days, so you will need to use another method of contraception, like condoms. You may also be required to take a pregnancy test after the injection has been given. 

Depo-Provera and Noristerat are injected into a muscle (usually in your buttocks) and Depo-Provera can also sometimes be injected into your arm. Sayana Press is injected beneath the skin at the front of the thigh or abdomen.

How often you need to have renewal injections depends on the type of injection you are given. Always check with your nurse or doctor when the next injection is due: 

  • Depo-Provera injections are every 12 weeks
  • Noristerat injections are every eight weeks
  • Sayana Press injections are every 13 weeks

Advantages of the contraceptive injection

  • It doesn’t interrupt sex
  • The injection works for 8, 12 or 13 weeks (depending upon which one is used)
  • It may reduce heavy periods
  • It may reduce period pain
  • It can be used by some women who cannot use the contraception that contains oestrogen
  • The injection is not affected by vomiting, diarrhoea or antibiotics (like some methods)
  • Using Sayana Press (self-injection) may mean only one visit to the clinic per year

Disadvantages of the contraceptive injection

  • Periods may be irregular or stop altogether
  • It can cause slight thinning of the bones by reducing bone mineral density (this usually recovers once the injections stop)
  • It may take a while for your periods to return to normal when you stop having the injection, this does not mean you cannot get pregnant, as it’s not possible to predict exactly when your periods and fertility will return to normal
  • Some women may put on weight when they use Depo-Provera, research has shown this is more common in the first six months of use
  • It can cause some side effects including headaches, mood swings, breast tenderness and irregular bleeding. Because the injection can’t be removed from your body (like an IUD, IUS or implant) if you do have any side effects they are likely to last as long as the injection and for some time afterwards 
  • It doesn’t protect you against sexually transmitted infections (STIs), so you will need to use a barrier method such as condoms
  • It can cause acne
  • There can be a very small risk of infection at the site of the injection

What can make the contraceptive injection less effective?

Follow-up injections must be given on time. If you miss just one injection, you are at risk of pregnancy.

If you think your next injection is late use condoms until you know that your contraception is definitely protecting you again.

If you have had unprotected sex and are worried you may need to use emergency contraception.

How will it affect my periods?

The injection may cause an irregular bleeding pattern, and your periods may be irregular, heavier, and longer or they may stop all together. 

However it is also important to check that the bleeding is not due to any other cause. It is recommended that you discuss any concerns that you may have with your nurse or doctor. It might be possible to give some additional medication that can help with the bleeding.

Using the contraceptive injection after having a baby

You can have the injection three weeks after giving birth. If you start the injection on or before day 21 you will be protected against pregnancy straight away. If the injection is started later than day 21 you will need to use an additional method of contraception for seven days.

If you are breastfeeding, the injection is usually given from six weeks after you have given birth, although it can sometimes be started sooner if appropriate. The contraceptive injection can be used safely while you are breastfeeding and will not affect your milk supply.

Using the contraceptive injection after having an abortion or miscarriage

You can start the injection immediately after a miscarriage or abortion and you will be protected from pregnancy straight away. If you start the injection more than five days afterwards you will need to use an additional method of contraception such as condoms for seven days.

Page last reviewed: August 2017
Next review due: August 2019