• 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.
• Check the woman's blood pressure, weight and body mass index.
• Check the UK Medical Eligibility Criteria to ensure that there are no contraindications.
• Assess the risk for sexually transmitted infection and, when appropriate, advise testing, promote safer sex, and/or refer for counselling.

In depth

• First-line options are monophasic preparations containing 30 micrograms of oestrogen, and either norethisterone or levonorgestrel.
• However, consider the person's preference, as any combined oral contraceptive (COC) can be provided first-line.

In depth

• Not currently using a regular method of contraception:
• Ideally start the COC on the first day of the period (or up to day 5) for immediate contraceptive cover.
• COCs can be started at any other time in the cycle, if pregnancy has been excluded. Additional contraception is needed for the first 7 days of taking the pill.
• Inform the woman that medical advice may differ from that included in the packet of pills.
• Specific advice for women who are amenorrhoeic, postpartum and breastfeeding, postpartum and not breastfeeding, or post-abortion is summarized in the table below.
• Starting immediately after oral emergency contraception:
• Levonorgestrel emergency contraception used — advise additional contraception (condoms or avoidance of sex) for the first 7 days of pill taking.
• Ulipristal acetate emergency contraception used — advise additional contraception (condoms or avoidance of sex) for the first 14 days of pill taking.
• Advise the woman to take a pregnancy test no sooner than 3 weeks after the last episode of unprotected sex.
• Using another COC, combined contraceptive patch, or progestogen-only pill:
• The new COC may be started immediately. There is no need to wait for the next menstrual period.
• However, the woman may want to complete the cycle of her current COC or progestogen-only pill, omitting any hormone-free interval (or the inactive pills of Every Day preparations), before starting the new COC. No additional contraceptive protection is required.
• Using a progestogen-only injectable:
• The COC should be started when the repeat injection would have been given.
• No additional contraceptive protection is needed if the COC is started < 14 weeks (98 days) after the injection (outside the terms of the product licence).
• Using a copper intrauterine device (IUD) or the levonorgestrel-releasing intrauterine system (IUS):
• The COC is most conveniently begun within 5 days of the start of menstrual bleeding. No additional contraceptive protection is needed. The IUD or IUS can be removed at that time.
• The COC can be started at any other time in the menstrual cycle, provided it is reasonably certain that she is not pregnant. However, she will need to abstain from sex or use additional contraceptive protection for the next 7 days.
• To provide the extra protection removal of the IUD or IUS could be delayed for at least 7 days.
• The IUD or IUS can be removed immediately unless she has had sexual intercourse in the past 7 days. In which case it should be left in until she has taken at least 7 pills sequentially.

In depth

• Follow up at 10–12 weeks after first prescriptions, and 6–12 monthly thereafter.
• Review blood pressure, risk factors, (e.g. new headaches), correct usage, lifestyle issues, adverse effects, and information on how to manage contraception relating to missed pills, diarrhoea and vomiting, surgery, and drug interactions.

In depth

• Restart/catch up with the pill cycle.
• When seven or fewer active COC pills have been missed, the woman should resume taking her pills as soon as possible.
• Restarting. If pills are missed in weeks 1, 2, or 3 of the pack: she should take the last missed pill as soon as possible and continue with the usual pill-taking schedule. Depending on when she remembers, she may take two pills at different times (the moment of remembering and her regular time), or two pills at the same time. For users of everyday COCs: if inactive pills are missed in week 4, she should throw away the missed inactive pills and continue the usual pill-taking schedule.
• Skipping the pill-free interval. If pills are missed in week 3 of the pack: she should finish the active pills in the current pack and then immediately start a new pack (omitting the pill-free interval or discarding any inactive tablets).
• When more than seven active COC pills have been missed, the woman needs to restart the COC as if she had not used it before.
• Assess if contraceptive protection has become unreliable.
• Loss of contraception is most likely if missed pills extend the pill-free (or inactive pill) interval to more than 7 days.
• The fpa (Family Planning Association) and the Faculty of Sexual and Reproductive Healthcare (FSRH), formerly the Faculty of Family Planning and Reproductive Healthcare (FFPRHC), regard contraception as becoming unreliable if:
• Two or more 20-microgram ethinylestradiol pills (Loestrin 20^®, Mercilon^®, Femodette^®) are missed — mnemonic: 'Two for twenty'.
• Three or more 30- or 35-microgram ethinylestradiol pills (all other COCs) are missed — mnemonic: 'Three for thirty'.
• The BNF (British National Formulary) regards:
• Contraception as unreliable if the delay is >= 24 hours (especially the first in the packet).
• Lost if more than 2 COC tablets are missed from the first 7 tablets in a packet.
• If contraceptive protection has become unreliable:
• Advise additional protection, such as condoms or abstinence, until the woman has taken her COC for 7 days in a row.
• Consider emergency contraception. If contraceptive protection has become unreliable and the woman has been sexually active without taking other precautions, consider the possibility of pregnancy and whether emergency contraception would be appropriate — see the CKS topic on Contraception - emergency.

In depth

• Liver enzyme–inducing drugs, some antibiotics, and some natural remedies, can reduce the efficacy of combined oral contraceptives (COCs).
• COCs can alter serum concentrations of other drugs, such as lamotrigine, ciclosporin, and theophylline.

In depth

• Liver enzyme–inducing drugs may reduce the efficacy of combined oral contraceptives (COCs). Commonly encountered drugs include:
• Antibiotics: rifampicin and rifabutin
• Anticonvulsants: carbamazepine, oxcarbazepine, phenytoin, barbiturates, primidone, topiramate.
• Antiretrovirals: particularly non-nucleoside reverse transcriptase inhibitors and ritonavir-boosted protease inhibitors. Drug interactions between certain antiretroviral agents and hormonal contraceptives could alter the safety and effectiveness of both the contraceptives and the anti-retroviral agents. For further information, see antiretrovirals.
• Herbal remedies: St John's wort
• If a liver enzyme–inducing drug is to be used long-term:
• An alternative contraceptive method that is unaffected by enzyme-inducing drugs should be considered, for example, a long-acting reversible method such as s depot medroxyprogesterone, levonorgestrel-releasing intrauterine system or a copper intrauterine device (IUD).
• If the woman wishes to use the COC as her primary contraceptive method while taking a liver enzyme–inducing drug, refer to (or consult with) a specialist. A COC regimen with at least 30 micrograms of ethinylestradiol daily should be used, and/or taking the COC without a pill-free interval — these uses are outside the terms of the product license.
• The consistent use of condoms is recommended.
• If a liver enzyme–inducing drug is to be used short term (e.g. 3 weeks):
• Additional contraceptive protection (e.g. condoms) should be used while the liver enzyme–inducing drug is being taken and for at least 4 weeks after stopping it. For women using rifampicin or rifabutin, consider continuing alternative methods for up to 8 weeks after stopping it.
• Emergency contraception should be considered if sexual intercourse has taken place while efficacy of the COC is doubtful and within the past 5 days — see the CKS topic on Contraception - emergency.

In depth

• Additional contraceptive precautions are not required during or after courses of antibiotics that do not induce liver enzymes.
• However, women should be advised about the importance of correct contraceptive practice during periods of vomiting or diarrhoea.
• Rifampicin and rifabutin induce liver enzymes. Therefore, if the woman is taking, or needs to take, rifampicin or rifabutin at the same time as a COC, follow the advice for interactions with liver enzyme-inducing drugs.

In depth

• If the woman is already receiving lamotrigine:
• If she wishes to start a combined oral contraceptive (COC), advise her:
• That a COC containing a minimum of 30 micrograms of ethinylestradiol should be used.
• That seizure control may worsen.
• That the maintenance dose of lamotrigine may need to be increased as much as two-fold, according to clinical response.
• If she wishes to stop a COC, advise her:
• That adverse effects associated with lamotrigine can increase.
• That the maintenance dose of lamotrigine may need to be decreased by as much as 50%, according to clinical response.
• If the woman is already using a COC and wishes to initiate lamotrigine:
• The usual escalation regimen for lamotrigine is recommended.

In depth

• A woman who vomits (for any reason) within 2 hours of taking a combined oral contraceptive (COC) should repeat the dose as soon as possible.
• If vomiting or severe diarrhoea persists for more than 24 hours, the instructions for missed pill should be followed (see Missed COC pills), counting each day of vomiting and/or severe diarrhoea as a missed pill:
• Additional contraceptive cover is required during the illness and for 7 days afterwards.
• If the illness occurs while taking the last 7 tablets, omit any pill-free period (or inactive tablets) and start the next cycle immediately.

In depth

• Identify and manage causes for bleeding irregularities such as missed pills, drug interactions, vomiting, severe diarrhoea.
• 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 COC 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.)
• After potential causes have been excluded:
• Encourage persevering for up to three months for new users.
• Consider stopping the COC for up to 7 days and then restarting (and using an alternative method while protection is lost).
• Changing to a different COC (with a higher dose of oestrogen, or higher dose of progestogen or different type of progestogen).
• Changing to another form of contraception.

In depth

• Stop the combined oral contraceptive (COC) 4 weeks before any major surgery, surgery to the legs, or surgery with prolonged immobilization of a lower limb.
• If emergency surgery or immobilization (e.g. fractured leg) is necessary, the COC should be stopped and treatment to prevent thromboembolism should be given.
• Advise the use of another method of contraception that will minimize the risk for venous thromboembolism.
• No precautions are necessary for minor surgery where the duration of anaesthesia and immobilization is short (e.g. laparoscopic sterilization, varicose vein surgery, and tooth extraction).
• The COC should normally be recommenced at the first menses occurring at least 2 weeks after full mobilization.
• To restart the COC, take the COC on day 1 of the first menstrual period that occurs at least 2 weeks after full mobilization. If the woman has used a progestogen-only injectable in the interim, the COC can be restarted before the next injection would be due.

In depth