What you need to know about the injection

The contraceptive injection contains progestogen, a copy of the naturally produced hormone progesterone.

If you use Sayana Press, you’ll inject it yourself 4 times a year into the skin of the thigh or abdomen. If you choose Depo Provera, a health professional will inject it 4 times a year into your bottom. It lasts 13 weeks and usually stops your period.

The injection works in three ways. It stops you from releasing eggs (ovulating) so that there’s no egg to be fertilised. It thickens the mucus in the entrance of the womb so that sperm can’t get through. It also thins the lining of the womb so that a fertilised egg can’t implant and grow.

The contraceptive injection

  • is very effective – one of the most effective methods to prevent pregnancy

  • is a long-term method – you only need to take action 4 times a year

  • is reversible, although it may take a little while (up to 18 months) after you stop using the injection for your fertility to go back to what’s normal for you

  • means you don’t need to remember it on a daily basis or when you’re having sex

Also known as

  • Depo

  • Depo-Provera

  • Sayana Press

  • self-injection

  • Noristerat

This is an excellent method of contraception for people who don’t want periods, for people who exercise regularly or don’t put on weight easily and for people who don’t want to have to think about their contraception very often.

Dr Paula Baraitser. Medical Director, SH:24

Likelihood of getting pregnant over a year

Used perfectly, the injection is over 99% effective. But none of us are perfect and it's more usual that people will miss injections, do them late or won't do them exactly right. So with more typical use, the injection is 94% effective.

This means typically 6 in 100 people using the injection will get pregnant in one year.

The injection is a good option if you...

  • have sickle cell disease – the injection can help to lower the severity of sickle cell crises

  • suffer heavy or painful periods, or have endometriosis – the injection can reduce or stop your bleeding

  • can’t take the combined pill or hormonal contraceptives containing oestrogen (for example if you get migraines with aura, or smoke and are over 35 years of age)

  • exercise a lot or don’t put on weight easily (injectable contraception can cause a small weight gain in some people) 

  • take medication that speeds up the metabolism of other hormonal contraceptives, for example, some epilepsy medications

  • are a trans man – 70% of people don’t have periods by the end of their first year on the contraceptive injection, which may be an advantage for you (it also doesn’t interfere with hormone treatments)

It’s not recommended for people who...

  • want a regular period

  • are trying to lose weight

  • are planning to become pregnant soon, since it can affect your fertility for up to 18 months after you stop using it

  • have several risk factors for heart disease, such as being overweight, a smoker or having a family history of heart disease

  • have risk factors for osteoporosis – this may be particularly important for those aged under 18 or over 45

  • currently have breast cancer or have a past history of breast cancer

  • have reduced liver function – this is because you need your liver to break down the hormones in the injection

  • are over 50

  • have irregular bleeding, unless you’ve investigated the treatable causes of it

Everything you wanted to know about sexual health and wellbeing - your questions answered by our expert team.