Once you have an injection or implant, you should be protected from pregnancy for as long as they are in place. There are two types of contraceptive injection. Depo-Provera is the most commonly used contraceptive injection. It protects you against pregnancy for 12 weeks. The other injection, Noristerat, gives contraceptive protection for 8 weeks.
Injections use a progestogen hormone.
This is injected into a muscle and is released very slowly into your body. This means that less than 1 woman in 100 will get pregnant in a year. Your injection may be less effective if you don't have your next injection on time, or if you take a prescribed medicine that affects the injection. These include medicines that treat epilepsy and tuberculosis. Always say that you are using a contraceptive injection if you are prescribed any medicines.