Injectable contraception

The injectable contraception contains an artificial progestogen hormone.

It is:

  • 99% effective when you use the method correctly every time
  • 94% effective when you don’t always use the method correctly

What is it?

An injection is given by a healthcare professional about every 12 weeks.

How it works

The hormone progestogen sits in the muscle and is slowly absorbed from the muscle into the blood over a course of 12 weeks. This prevents ovulation (an egg being released).

If you are considering injectable contraception, you should talk to a doctor, who will assess if this contraceptive option is best for you.


  • Does not interrupt sex.
  • May protect against cancer of the womb lining.
  • Useful for women who forget to take their pill daily.
  • Can be used by women who cannot take oestrogen in the combined oral contraceptive pill, such as women over 35 who smoke.


  • May cause irregular bleeding at first. Then can create a lighter period or no period at all in most cases.
  • Must be given by a doctor or a nurse.
  • Cannot be immediately reversed if you have side-effects.
  • Can take six to twelve months for regular periods and fertility to return to normal.
  • Does not protect against sexually transmitted infections.