Definitions of the grades of recommendation based on levels of evidence (A-C, Good Practice Point) are provided at the end of the "Major Recommendations" field.
What should be discussed when prescribing drugs to women using hormonal contraception?
- Clinicians should consider the possibility of a drug interaction when prescribing contraception and when prescribing other medicines to women using hormonal contraception (Good Practice Point).
- Clinicians giving women information on contraceptive options should enquire about current and previous drug use; prescription, nonprescription and herbal drug use; and specifically about use of drugs which induce liver enzymes and non-liver enzyme-inducing antibiotics (Good Practice Point).
- Women should be informed that some drugs might reduce the effectiveness of hormonal contraception and should be advised where to seek advice if other drugs are taken (Good Practice Point).
- After counseling, women using short courses of drugs that interact with hormonal contraception may choose to continue their current hormonal method even if additional contraception, such as condoms, is required. However, women on long-term courses of drugs that continue to interact with hormonal contraception should be encouraged to consider a contraceptive method that is unaffected by the interacting drug (Good Practice Point).
What drugs may reduce the efficacy of hormonal contraception?
Liver Enzyme-inducing Drugs
- Women should be informed that drugs which induce liver enzymes can reduce the efficacy of combined hormonal contraception, progestogen-only pills (POPs), and implants but do not appear to reduce the efficacy of progestogen-only injectables or the levonorgestrel-releasing intrauterine system (LNG-IUS) (Grade C).
Refer to Table 1 titled, "Drugs that induce liver enzymes and relevant associated drugs that do not induce liver enzymes" in the original guideline document for additional information.
Non-liver Enzyme-inducing Antibiotics
- Women should be informed that non-liver enzyme-inducing antibiotics can reduce the efficacy of combined hormonal contraception but there is no reduction in the efficacy of progestogen-only methods (Grade C).
What advice should be given to women using hormonal contraception and liver enzyme-inducing drugs?
Combined Hormonal Contraception
- Women taking liver enzyme-inducing drugs who wish to use combined oral contraception (COC) should choose a regimen containing at least 50 micrograms ethinylestradiol (EE) daily. Additional contraceptive protection, such as condoms, should be used until 4 weeks after the liver enzyme-inducing drug has been stopped. Information should be given on the use of alternative methods of contraception if liver enzyme-inducing drugs are to be used long term (Grade C).
- Breakthrough bleeding does not necessarily indicate low serum EE concentrations and risk of ovulation. Nevertheless, women using liver enzyme-inducing drugs with breakthrough bleeding may increase their dose of EE above 50 micrograms daily (Good Practice Point).
- No evidence was identified that supports omitting or reducing the pill-free interval to reduce the risk of ovulation in women using liver enzyme-inducers (Good Practice Point).
- Women using liver enzyme-inducing drugs may use a combined contraceptive patch with additional contraceptive protection, such as condoms, until 4 weeks after the liver enzyme-inducing drug has been stopped. Information should be given on the use of alternative methods of contraception (Grade C).
- Women using even short courses of rifampicin (for prophylaxis) should be advised to use additional contraception during the course and for 4 weeks afterwards (Grade C).
Refer to Table 2, "Advice regarding contraceptive use for women using liver enzyme-inducing drugs" in the original guideline document for additional information.
Progestogen-only Contraception
- Women using liver enzyme-inducing drugs should be advised that progestogen-only injectables are unaffected and can be continued with the usual injection interval (Grade C).
- Women using liver enzyme-inducing drugs in the short term may choose to continue with progestogen-only implants. Additional contraceptive protection, such as condoms, should be used until 4 weeks after the liver enzyme-inducing drug has stopped. Information should be given on the use of alternative contraception if liver enzyme-inducing drugs are to be used long term (Good Practice Point).
- Women using POPs should be advised to consider alternative contraception if liver enzyme-inducing drugs are used (Grade C).
- Women can be advised that the LNG-IUS appears to be unaffected by liver enzyme-inducing drugs (Grade B).
- Women using liver enzyme-inducing drugs who require progestogen-only emergency contraception (POEC) should be advised: to take a total of 2.25 mg levonorgestrel (LNG) as a single dose as soon as possible and within 72 hours of unprotected sex; that this use is outside the product license; and about the alternative use of an intrauterine contraceptive device (IUD) (Grade C).
What advice should be given to women using hormonal contraception and non-liver enzyme-inducing antibiotics?
- Women should be advised that pregnancies have been reported in COC users taking non-liver enzyme-inducing antibiotics, but the evidence does not generally support reduced COC efficacy and causation (Grade B).
- A COC user taking a short course (less than 3 weeks) of non-liver enzyme-inducing antibiotics should be advised to use additional contraceptive protection, such as condoms, during the treatment and for 7 days after the antibiotic has been stopped. If fewer than seven active pills are left in the pack after antibiotics have stopped, she should omit the pill-free interval (or discard any inactive pills) (Grade C).
- A combined contraceptive patch user taking a short course (less than 3 weeks) of non-liver enzyme-inducing antibiotics (except tetracycline) should be advised to use additional contraceptive protection, such as condoms, during the treatment and for 7 days after the antibiotic is stopped. If there are less than 7 days remaining before her usual patch-free week, another patch should be applied when due for changing and the patch-free week delayed by 7 days (Grade C).
- A woman who is an established user of non-liver enzyme-inducing antibiotics (longer than or equal to 3 weeks) does not require additional contraceptive protection when starting combined hormonal contraception unless she changes to a different antibiotic (Grade C).
- Women should be informed that the efficacy of progestogen-only methods of contraception is not reduced by non-liver enzyme-inducing antibiotics and additional contraceptive protection is not required (Grade C).
- Women using non-liver enzyme-inducing antibiotics (short- or long-term) who require POEC may be advised that the usual dose (1.5 mg within 72 hours of unprotected intercourse) is appropriate (Grade C).
Refer to Table 3, "Advice regarding contraceptive use for women using non-liver enzyme inducing antibiotics" in the original guideline document for additional information.
Definitions:
Grades of Recommendation
A Evidence based on randomised controlled trials (RCTs)
B Evidence based on other robust experimental or observational studies
C Evidence is limited but the advice relies on expert opinion and has the endorsement of respected authorities
Good Practice Point where no evidence exists but where best practice is based on the clinical experience of the Expert Group
