• In young women and women with special needs, assess their competence to decide, and support them in making their own decisions about contraception.
• Exclude pregnancy.
• Assess the risk for sexually transmitted infection and, when appropriate, advise testing, promote safer sex, and/or refer for counselling.
• Check the woman's blood pressure, weight and body mass index (BMI).
• Check the UK Medical Eligibility Criteria to ensure that the woman is eligible for a progestogen-only pill (POP).

In depth

• Any licensed progestogen-only pill (POP) may be used first-line.
• However, rules about missed pills differ between products, and this may affect their acceptability.
• If the woman weighs more than 70 kg, then consider the desogestrel-only pill, Cerazette^®, as the first line option.
• Irregular bleeding (particularly in the first few months) may be more of a problem with the desogestrel-only pill than with other POPs.

In depth

• Women who are not amenorrhoeic and have not been pregnant in the past 6 months:
• Start the progesterone only pill (POP) on the first day of the period (licensed use), or up to day 5 of the cycle (unlicensed use), for immediate contraceptive cover.
• The POP can started at any other time in the cycle, but additional contraception is needed for the first 48 hours of taking the pill (unlicensed use).
• Inform the woman that the instructions in the packet may differ from those provided by the healthcare professional.
• If starting immediately after oral emergency contraception:
• Levonorgestrel emergency contraception used — advise additional contraception (condoms or avoidance of sex) for the first 2 days of use.
• Ulipristal acetate emergency contraception used — advise additional contraception (condoms or avoidance of sex) for the first 9 days of use.
• Advise the woman to take a pregnancy test no sooner than 3 weeks after the last episode of unprotected sex.
• If the woman is amenorrhoeic:
• Start the POP at any time, provided that it is reasonably certain that a woman is not pregnant (unlicensed use).
• Advise additional contraceptive protection (such as condoms) for the first 48 hours of pill taking.
• If the woman is postpartum and not breastfeeding:
• Contraception is not required before day 21 postpartum.
• Ideally, start the POP on day 21 postpartum for immediate contraceptive protection — this is the only licensed use for postpartum women.
• However, the POP can be started before day 21 if requested.
• If started after day 21, advise additional contraceptive protection (such as condoms) for the first 48 hours of pill taking.
• If the woman is postpartum and breastfeeding:
• Start on or before day 21 postpartum for immediate contraceptive protection.
• If started after day 21, advise additional contraceptive protection (such as condoms) for the first 48 hours of pill taking.
• These are unlicensed uses.

In depth

• Changing from a combined oral contraceptive (COC): the progestogen-only pill (POP) may be started immediately.
• Changing from an injectable progestogen-only contraceptive: the POP should be started on the day that the injection would have been given.
• Changing from a copper intrauterine device (IUD) or levonorgestrel-releasing intrauterine system (IUS):
• The POP is most conveniently begun within 5 days of the start of menstrual bleeding. No additional contraceptive protection is needed. The IUD can be removed at this time.
• The woman can also start a POP at any other time, if it is reasonably certain that she is not pregnant. Because the POP will become effective after 48 hours, the IUD or IUS should not be removed before this if she has been sexually active in the past 7 days, or if she requires interim protection from the IUD or IUS.
• Changing from a non-hormonal method (other than a copper IUD): start the POP within 5 days of the start of menstrual bleeding:
• If the POP is started outside of day 5, additional contraception should be used for the first 48 hours.

In depth

• First follow up at 10–12 weeks and then at least every 12 months thereafter, provided there are no problems.
• Review should include risk factors, correct use, lifestyle issues, adverse effects, possible drug interactions and information on how to manage contraception relating to missed pills and potential drug interactions.

In depth

• A woman who vomits (for any reason) within 2 hours of taking a progestogen-only pill (POP) should repeat the dose as soon as possible.
• If she is now more than 3 hours late (or 12 hours for desogestrel), continues to vomit or has very severe diarrhoea, the woman should follow the instructions for missed pills.
• If vomiting or severe diarrhoea persists for more than 24 hours, the woman should follow the instructions for missed pills, counting each day of vomiting and/or severe diarrhoea as a missed pill:
• Additional contraceptive cover is required during the illness and for 48 hours afterwards.

In depth

• Missed pill:
• Desogestrel (Cerazette^®): > 12 hours late (i.e. > 36 hours since taking the last pill).
• Other progestogen-only pills: > 3 hours late (i.e. > 27 hours since taking the last pill).
• If the woman has missed any progestogen-only pills, she should:
• Take a progestogen-only pill as soon as possible, then continue taking the pills as before. This can mean taking two pills within 24 hours.
• Use additional contraceptive protection for the next 48 hours.
• Consider whether emergency contraception is required. For more information, see the CKS topic on Contraception - emergency.

In depth

• Some drugs and herbal remedies may interfere with the effectiveness of progestogen-only pills (POPs).
• Women taking liver enzyme–inducing drugs should use additional contraception (e.g. condoms) whilst taking the drug and for 4 weeks after finishing the course:
• Commonly encountered liver enzyme–inducing drugs are:
• Antibiotics: rifampicin and rifabutin.
• Anticonvulsants: carbamazepine, oxcarbazepine, phenytoin, phenobarbital, primidone, topiramate.
• Herbal remedies: St John's wort.
• Antiretrovirals: drug interactions between certain antiretroviral agents and hormonal contraceptives could alter the safety and effectiveness of both the hormonal contraceptives and the antiretroviral agents. See antiretrovirals.
• Antibiotics that do not induce liver enzymes (i.e. all antibiotics except rifampicin and rifamycin) do not reduce the effectiveness of POPs.
• Emergency contraception should be considered if sexual intercourse has taken place in the past 5 days and the efficacy of the POP is doubtful — see the CKS topic on Contraception - emergency.

In depth

• Menstrual irregularities are common. Some women have frequent or prolonged bleeding, whilst some experience amenorrhoea.
• Identify and manage causes for bleeding irregularities such as missed pills, drug interactions, vomiting, severe diarrhoea, pregnancy.
• Exclude or manage other situations which could result in unscheduled bleeding, such as:
• Sexually transmitted infections.
• Risk of STI if the woman is under 25 years, or has a new sexual partner, or more than one partner in the last year.
• Pregnancy.
• Gynaecological conditions such as cervical cancer. Provided there is consistent and correct use of contraception, speculum examination is warranted:
• For persistent bleeding beyond the first 3 months of use.
• For new symptoms or a change in bleeding after at least 3 months of use.
• If the woman has not participated in a National Cervical Screening programme.
• If requested by the woman.
• After a failed trial of modification of POP treatment (at least 6–8 weeks).
• If there are other symptoms such as pain, dyspareunia, or post coital bleeding. (Note that these symptoms also warrant pelvic examination.)
• If frequent or prolonged bleeding occurs, consider the use of a different progestogen-only pill (POP).
• If the woman experiences amenorrhoea, exclude pregnancy. The POP can then be continued.

In depth