Contraceptive injection

The contraceptive injection (Depo-Provera, Sayana Press or Noristerat) is used to prevent pregnancy.

If used correctly, the contraceptive injection is 99% effective. This means that 1 in 100 people who use the injection will become pregnant in a year.

In real world use about 6 in 100 people become pregnant in a year because people forget to get their next injection (94% effective).

It does not protect you against sexually transmitted infections (STIs).

Depo-Provera contraceptive injection

How the injection works

The injection prevents pregnancy by releasing progestogen which:

  • prevents you from releasing an egg (ovulating)
  • makes it difficult for sperm to get to an egg
  • thins the womb lining, so there’s less chance an egg will attach to it

There are 3 types of injection used in the UK.


This lasts for 13 weeks. You usually have this injection in your bum. Sometimes you may have it in your upper arm.

This type of injection is done by a doctor or nurse.

Sayana Press

This lasts for 13 weeks. You usually have this injection in your lower tummy or the front of your thigh.

You normally learn how to do this injection yourself.


This lasts for 8 weeks. You usually have this injection in your bum. Sometimes you may have it in your upper arm.

It’s usually used for short periods of time – for example, if your partner is waiting for a vasectomy.

This type of injection is done by a doctor or nurse.

When it starts to work

You can have the injection at any time during your menstrual cycle, as long as you’re not pregnant.

If you have it during the first 5 days of your cycle, you’ll be immediately protected against pregnancy.

If you have it on any other day of your cycle, you should use additional contraception such as condoms for 7 days.

After giving birth

You can have the contraceptive injection any time after you’ve given birth.

If you start injections on or before day 21 after the birth, you’ll be protected against pregnancy.

If you start injections after day 21, you’ll need to use additional contraception such as condoms for 7 days.

After a miscarriage or abortion

You can have the injection immediately after a miscarriage or abortion. You’ll be protected against pregnancy straight away.

If you have the injection more than 5 days after a miscarriage or abortion, you’ll need to use additional contraception for 7 days.

Who can use the injection?

Most people can use the contraceptive infection, however it might not be suitable for some people. Your doctor or nurse will talk about this with you.

You should not use the injection if you:

  • think you might be pregnant
  • do not want your periods to change
  • want to have a baby in the next year
  • have bleeding in between periods or after sex
  • have arterial disease or a history of heart disease or stroke
  • have liver disease
  • have breast cancer or have had it in the past
  • are at risk of osteoporosis

What if I’m taking other medicines?

The contraceptive injection is not affected by other medication.

Side effects of the injection

The contraceptive injection may cause side effects. You should consider these carefully before deciding if it’s right for you.

Disrupted periods

Your periods may change significantly during the first year of using the injection. They’ll usually become irregular and may be very heavy, or shorter and lighter, or stop altogether. This may settle down after the first year but may continue as long as the injected progestogen remains in your body.

It can take a while for your periods and natural fertility to return after you stop using the injection. You may have to wait longer for your periods to return to normal if you’re trying to get pregnant.

Until you are ovulating regularly each month, it can be difficult to work out when you are at your most fertile. In some cases, it can take 3 months to a year for your periods to return to normal.

Weight gain

You may put on weight when you use the contraceptive injection, particularly if you’re under 18 years old and are overweight with a BMI (body mass index) of 30 or over.

Other side effects

Other side effects that some people report are:

  • headaches
  • acne
  • breast tenderness
  • mood changes
  • loss of sex drive

Benefits of using the injection

Some benefits of the contraceptive injection are that:

  • each injection lasts for either 8 or 13 weeks
  • it doesn’t interrupt sex
  • the injection is an option if you can’t use contraception containing oestrogen such as the combined pill, contraceptive patch or vaginal ring
  • you do not have to remember to take a pill every day
  • the injection is safe to use while you’re breastfeeding
  • the injection is not affected by other medicines
  • the injection may reduce heavy, painful periods and help with premenstrual symptoms for some women
  • the injection offers some protection from pelvic inflammatory disease (the mucus from the cervix may stop bacteria entering the womb) and may also give some protection against cancer of the womb

Risks of using the injection

Sometimes the area of skin where the injection has been injected can become infected. If this happens, the area will be cleaned and may be treated with antibiotics.

In very rare cases, some people may have an allergic reaction to the injection.

Some women who use Sayana Press get a dimple where it’s been injected.

Depo-Provera can affect your oestrogen levels. This can cause slight thinning of the bones which is reversed if you stop using the injection. This doesn’t increase your risk of breaking a bone.

You should speak to your doctor or nurse about this before starting the contraceptive injection.

Where can you get the injection?

You can get the contraceptive injection for free from:

If you’re under 16

Anyone can get contraception for free in Scotland, even if you’re under 16.

If you’re under 16, they might encourage you to tell your parents, but you do not have to.

The only time a professional might need to tell someone else is if they think you’re at risk of harm, such as abuse. The risk would need to be serious. They’d usually talk about it with you first.

Last updated:
30 December 2022