The contraceptive injection is given into a muscle into your arm or bottom and works in a number of ways. Firstly, it stops any eggs being released from the ovaries. Secondly, it thickens the mucus in the neck of the womb which makes it very difficult for sperm to get through. Finally, it affects the lining of the womb which makes it difficult for a fertilised egg to implant there.
Like a lot of other methods of contraception, the contraceptive injection offers no protection against sexually transmitted infections.
Depo-Provera is the most common type used in Scotland and will protect you for up to 12 weeks. Noristerat is an alternative contraceptive injection and is effective for up to 8 weeks. After this you will need to get another injection to stay protected.
Some prescribed medications (such as some of those for epilepsy) can mean that you need a shorter gap between injections. If you are taking any other medication, it's important to discuss this with the person prescribing your contraception.
If used correctly it's more than 99% effective. This means that fewer than one woman in 100 who use the injection will become pregnant in a year. However, you must remember to get your next scheduled injection on time, if you are late you risk getting pregnant.
Injections are available from your GP or sexual health clinic and will be given by a trained doctor or nurse.