There are 2 types of injections:
IMPORTANT! Make sure that you go back for your repeat injection at the right time! A time lapse between injections could mean the injection won't work properly to prevent pregnancy.
Side effects With the injection, you may have irregular bleeding like light spotting, or you may have heavier periods at first. Later on, you may have no monthly bleeding at all. Not getting your period doesn't mean that blood is collecting in your body or that you can't get pregnant in future.
Some people may gain some weight at first as your body gets used to the injection, but this doesn't last long, and doesn't happen to everyone.
Some people also get headaches, dizziness, bloating, acne, tender breasts and mood changes. It may also make heavy periods lighter, or relieve premenstrual symptoms (PMT) for some.
Caution: think about this! If you want to get pregnant after having the injection, you might have to wait up to 10 months for your body to become fertile again.