Progestogen-only Injectable (POI) Contraception

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Progestogen-only injectable contraception is a hormonal type of contraception that is given through an injection. It contains a synthetic form of the hormone progesterone, known as progestin or progestogen. They provide protection against pregnancy for up to 8 to 14 weeks.


  • Medroxyprogesterone acetate (DMPA)
  • Norethisterone enanthate (NET-EN)

Mechanism of action

  • This hormone works primarily by suppressing ovulation (preventing the release of an egg from the ovaries).
  • It also thickens cervical mucus, making it more difficult for sperm to reach and fertilize an egg.
  • It can thin out the uterine lining, making it less suitable for the development of the fertilized egg.


When used correctly (getting the injection on time), progestogen-only injectable contraception is highly effective, approximately 0.2% in the first year of use. However, real-world effectiveness may be slightly lower due to missed or delayed injections and is typically about 6%.



  • Convenience – do not need to remember to take a daily pill, and it offers long-lasting protection.
  • Very effective compared to oral pills or condoms.
  • Can be used to treat conditions or symptoms in endometriosis, adenomyosis or uterine fibroids.
  • Long-term users may lower the risk of developing these conditions.
  • Can provide relief from heavy or painful periods.
  • Effectiveness is not affected by weight.
  • Does not interfere with sexual spontaneity.
  • Can be used while breastfeeding.


  • Must be administered by a healthcare provider every 8 -14 weeks (depending on the type)
  • Does not protect against sexually transmitted infections (STIs).
  • Irregular bleeding can be a nuisance for some users.
  • It may take several months after discontinuation for fertility to return to normal (up to 1 year in some women).

Side Effects:

  • Change in menstrual cycles – include irregular menstrual bleeding (which may be lighter or heavier). Some women will experience a complete absence of periods (amenorrhea), which can be beneficial for those with heavy or painful menstruation (in conditions such as adenomyosis or endometriosis).
  • Other side effects include weight gain, especially in younger women with higher BMI, mood changes, headaches, breast tenderness.
  • Uncommon – acne, decreased libido, hot flushes, hair loss and vaginitis.
  • Some individuals may also experience a decrease in bone density with long-term use, so it’s important to discuss this with a healthcare provider. Fortunately, this will revert to normal after discontinuation.

Who should not use the injectables.

These injections are safe for the majority of women of reproductive age. However, there are certain medical conditions that makes these unsuitable:

  • Known or suspected pregnancy.
  • Before evaluation of genital bleeding.
  • Liver disease, including tumors.
  • Cancer of the breast (past or present).
  • Hypersensitivity to any component of the product.

Timing of first injection (Initiation):

No additional protection needed if started –

  • up to Day 5 of menses.
  • switching from COCs: injection no later than Day 5 of pill-free interval.
  • switching from intrauterine device: initiate immediately on the day of removal.
  • switching from implant: initiate immediately on the day of removal.
  • postabortion (spontaneous or induced): initiate immediately.
  • postpartum non-breastfeeding: generally 3–4 weeks postpartum.
  • fully breastfeeding: initiate 6 weeks or longer.
  • perimenopausal: begins by day 5 of menses.

If not in line with the above criterias, then a woman needs protection for 7 days (using a condom)

What you need to know prior to injection

  • This is a good choice for women who has completed her family and / or has certain gynaecological problems associated with painful or heavy menstruation. Reduction in flow or absence of menses will offer relief.
  • Women should be able to accept changes in menstrual bleeding (including absence of menses) and up to 1 year delay in return of fertility.
  • Get adequate calcium intake.
  • If worry about weight gain, women should limit their calorie intake and get regular exercise.
  • Must be able to come on time for next injection. The interval will depend on the type of injectables given – please ask your healthcare provider and make sure you return for the next injection on time. Delay in the administration of the injectable may result in unplanned pregnancy.

See your healthcare provider if you have the following symptoms:

  • Injection site reactions – severe pain and swelling.
  • Pelvic/lower abdominal pain: need to exclude ectopic pregnancy.
  • Prolonged or heavy vaginal bleeding.
  • Yellowish discoloration skin (jaundice), light coloured stools.
  • Severe abdominal pain or leg swelling as these could be signs of a blood clots.

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