injectable contraceptives

Last reviewed 08/2019

Injectable hormonal contraceptives are slow release, long lasting progesterone preparations administered i.m. at intervals from 1 to 6 months. Common preparations include medroxyprogesterone acetate and norethisterone enanthate.

The main disadvantages are due to the progesterone. Many experience some degree of menstrual disturbance; in some, this can be irregular uterine bleeding which may be heavy and prolonged whilst others may experience amenorrhoea.

Injectable contraception however, may be particularly suited:

  • following rubella vaccination in the puerperium
  • while awaiting for vasectomy to be proven in a partner
  • in women with a chaotic lifestyle where taking an oral contraceptive regularly is difficult

Injectable hormonal contraception has a failure rate of 1 in 1000. Thus this form of contraception is more effective than the combined pill and female sterilisation (1 in 200 failure rate) (1).


  • (1) Prescriber (2001), 12 (5), 83-95.
  • (2) BNF 7.3