The contraceptive injection, also known as the depo or depo-provera, is a long-acting contraception containing the hormone progestogen. It has to be given every 12 weeks in order to work.
The hormone is injected into a muscle, usually your bottom.
How does it work?
Its main way of working is to stop the release of an egg; but it also works by thickening cervical mucous (to prevent sperm from being able to reach an egg) and by thinning the lining of the womb - so that if an egg was fertilised, it would not be able to implant.
How effective is it?
The contraceptive injection is over 99% effective in preventing pregnancy.
Advantages of the contraceptive injection:
- you only have to remember to take it once every 12 weeks and it does not interrupt sex
- lighter or no periods
- reduced period pain and less premenstrual symptoms
- research also suggests that it provides some protection against womb cancer and pelvic inflammatory disease.
Disadvantages of the contraceptive injection:
Using the contraceptive injection can disrupt your periods, cause irregular bleeding, and for some women cause periods to be heavier and longer.
Other side effects include headaches, mood changes, weight gain, spotty skin and breast tenderness, as well as a potential for small weight gain.
Also, in the short-term, once you have stopped using the injection it may take up to a year for your fertility to return to normal.
If started at a very young age, the contraceptive injection may also stop bones from reaching their full thickness, which may lead to problems in later life for women with osteoporosis. However, the evidence for this is not very strong.
Things to bear in mind:
The contraceptive injection may not be suitable for women aged below 19, because bone development is still taking place during your teenage years. You will be counselled about the risks of osteoperosis before you are prescribed the medication.
The injection is not reversible, so if you have side effects you will not be able to stop them until the injection has worn off after 12 weeks.
Most importantly, the contraceptive injection does not provide any protection against HIV or other sexually transmitted infections like a condom does.
Where can I get it from and how much does it cost?
The contraceptive injection is available free on the NHS. You can only get it on prescription. This can be from your GP, a practice nurse or a sexual health or young person's clinic.