Contraception – Progesterone Only Pill – POP
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  • Generally used when COC is contra-indicated
  • Not as effective as COC, although still >99% effective
  • Often used in those on COC before / during / after surgery


99% effective when used correctly
Cerazette, Mini Pill
Thickens cervical mucus,
thins lining of womb,
Higher dose pop ie. cerazette also inhibits ovulation
Can be taken in those with CI to COC ie. breastfeeding, older women, cardiovascular risk, DM
>35yrs who smoke
normal fertility resumed immediately
Dysfunctional bleeding ie. irregualar, IMB. In many cases, bleeding is reduced or event absent
Breast tenderness, acne, weight change, headaches
Small inc ectopic pregnancy
Increased risk of ovarian cysts
Previous cysts or ectopic – may have slight inc risk ectopic if get pregnant
Take continuously for 28days at same time.
Mini Pill – If miss pill >3hrs must take barrier contraception for 7d
Cerazette – allows 12 hour window
Advantages over POP
  • Can use when breastfeeding
  • Not age restricted
  • Can help to reduce painful periods


  • Thickens cervical mucus
  • Alters lining of the uterus, making it difficult for implantation to take place
  • Some (Cerazette) also prevent ovulation – this probably means cerazette is more effective than other POP’s but there is no conclusive evidence yet

Side effects

  • Far fewer serious side effects than COC
  • Periods may be irregular / light / may stop completely. In some cases, they can become more heavy
  • Temporary side effects in first few months of treatment:
    • Breast tenderness, acne, weight change, headaches
  • Ovarian cysts – small risk, may cause pelvic pain, but usually resolve spontaneously.
  • Increased risk of ectopic pregnancy – in the unlikely event of pregnancy occurring

Advantages of POP over COC

  • Can use when breast feeding
  • Useful when COC is contra-indicated – and POP has far fewer contraindications
  • Can be used at any age:
    • Particularly useful in smokers over 35, in which COC is CI’d
    • Can reduce premenstrual symptoms and painful periods


Time window for admission during which the pill is effective is small (3 hours). However, the pill Cerazette allows a 12 hour window, similar to COC. Sometimes the regular (3hr window) POP is called the Mini Pill.

Starting treatment

Start on the first day of the cycle. If started within the first 5 days, protection is immediate
If started after day 5, use condoms or another contraception for 2 days

  • Those with a short menstrual cycle (<23 days) may not be protect if they start on day 4 or 5, as ovulation may occur early. Advise condoms for 2 days after commencing POP

After miscarriage / abortion

  • If <24 weeks, start straight away
  • If >24 weeks seek advice

After Pregnancy

Does not interfere with lactation, or increase the risk of thromboembolic event, and thus can be start straight after pregnancy

A small amount of progesterone does enter the breast milk, but this does not cause any adverse effects in the child

If started after 21 days after birth, use an additional method of contraception for 2 days

Missed pills

Take the missed pill and the next pill s soon as you remember. If the missed pill was >3 hours late (12 hours for cerazette), then you are not protected, and condoms should be used for 2 days.

Vomiting and diarrhoea

  • If this occurs within two hours of taking the pill, use condoms or another method of contraception for 2 days after


Fewer than COC – e.g. antibiotics are generally not a problem, however, any liver enzyme inducing drugs may still interact.
  • Additional contraception (e.g. condoms) should be used during treatment with the enzyme inducing drug, and for 4 weeks after

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Dr Tom Leach

Dr Tom Leach MBChB DCH EMCert(ACEM) FRACGP currently works as a GP and an Emergency Department CMO in Australia. He is also a Clinical Associate Lecturer at the Australian National University, and is studying for a Masters of Sports Medicine at the University of Queensland. After graduating from his medical degree at the University of Manchester in 2011, Tom completed his Foundation Training at Bolton Royal Hospital, before moving to Australia in 2013. He started almostadoctor whilst a third year medical student in 2009. Read full bio

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