Tetracyclines Hormonal contraceptives

Evidence is very limited but it has been suggested that all patients given long-term minocycline treatment should be well screened for the development of pigmentation, particularly if they are taking other drugs such as the oral contraceptives that are known to induce hyperpigmentation. Remember also that very rarely contraceptive failure has been associated with the use of minocycline and other tetracyclines, see Hormonal contraceptives + Antibacterials Tetracyclines , p.983. 

When acne is severe it may require medidnes that have to be taken by mouth and these may be stronger antibiotics combined with hormone therapy. Tetracyclines and erythromycin are typically used and they have to be taken for many weeks, but there are signs that bacteria are becoming resistant to these antibiotics and if there is no improvement in the acne within three months then this type of treatment has to be discontinued, or a much stronger antibiotic tried. Hormone therapy is available for young women with severe acne and this can block the sebum-stimulating effect of natural hormones - as well as having a contraceptive effect. 

Contraceptive efficacy can be decreased when taken concurrently with drugs that increase the metabolism of hormones (e.g., CYP450 inducers). Similarly, drugs that reduce enterohepatic recycling of COCs (e.g., tetracycline, penicillins) can also reduce efficacy. 

Only 3 reports of pregnancies were identified in women who took metronidazole and an oral contraceptive (unspecified) in the adverse reactions register of the CSM in the UK for the years 1968 to 1984. A survey of oral contraceptive failure identified one failure due to metronidazole (48 of a total of209 cases were attributed to antibacterials), and a follow-up study identified one fiuther case. Another survey found one contraceptive failure in a woman taking metronidazole, but she was also taking dox-ycycline (see Hormonal contraceptives + Antibacterials Tetracyclines , p.983). It is possible that these cases represent chance associations. 

The interactions between the oral contraceptives and tetracyclines summarised here are all that have been identified in the literature. Much of the evidence is anecdotal with insufficient controls (if any). These interactions are not adequately established and the whole issue remains controversial. Bearing in mind the extremely wide use of both drugs, any increase in the incidence of contraceptive failure above the accepted failure rate is clearly very low indeed. On the other hand, the personal and ethical consequences of an unwanted pregnancy can be very serious. For this reason, the Faculty of Family Planning and Reproductive Health Care (FFPRHC) Clinical Effectiveness Unit recommends that an additional form of contraception, such as condoms, should be used while taking a short course of antibacterials that do not induce liver eiKymes, and for 7 days after the antibacterial has been stopped. See Hormonal contraceptives + Antibacterials Penicillins , p.981, for more detailed information on how to manage this interaction. 

The FFPRHC advise that additional contraceptive protection is not required in established users of the combined hormonal contraceptive patch taking tetracycline. This is in line with the findings of the study cited above. 

Note that doxycycline is increasingly used in the treatment of malaria. See Hormonal contraceptives + Antibacterials Tetracyclines , p.983, for further information on possible combined hormonal contraceptive failure with tetracyclines. 

The reliability of progestogen-only methods of hormonal contraception are not affected by antibacterials that do not induce liver enzymes, such as the penicillins and tetracyclines. 

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