There are two contraceptive injections to choose from - Depo Provera that lasts for 14 weeks, and Noristerat that lasts for 8 weeks (but you can only use it for a maximum of 16 weeks).
An implant is a small, flexible, rod that is put in the upper part of the arm and works for up to 3 years.
The main advantage is you don't have to worry about remembering to use it, so they are good if you're a bit forgetful. However, like the pill and the IUD they do not offer any protection against sexually transmitted infections.
If there is any possibility of infection, you should use condoms as well.
Most women choose implants after trying the pill or condoms. There are many reasons women change, including concerns about or actual side effects of the pill, wanting to stop using condoms, forgetting to take the pill, irregular periods and to reduce the risk of pregnancy or because of problems with other methods.
Before changing your contraception you can read leaflets about what's available or talk to your GP, Family Planning or Brook clinic staff. Remember, implants and injections do not suit everyone, so you'll need to see what you prefer.
Many women are happy with the injection; but some stop taking it because of health concerns. Some use implants or injections as contraception after childbirth, although one woman thought two weeks after having her baby was too soon for an injection.
Last reviewed April 2010.
Last updated April 2010.