Since 1991 when dental practitioners were advised to discuss the subject of reduced effectiveness of oral contraceptives during antibiotic use, research has not clearly established the mechanism by which this interaction takes place. The failure rate of oral contraceptives used concurrently with antibiotics is similar to the failure rate of oral contraceptives in general (between 1 and 3 percent). In oral contraceptives, levels of the principal active ingredient being ethinyl estradiol, do not seem to be altered by commonly used antibiotics. Recently, however, a report identified some antibiotics used in dentistry such as amoxicillin, ampicillin, metronidazole, and tetracycline as drugs which may reduce the effectiveness of oral contraceptive.
Therefore, it may be prudent for women to use a backup form from of contraception throughout antibiotic therapy and for 1 week after completion or early cessation of the antibiotic course.
Dentists are being advised to do the following:
- Advise the patient to maintain compliance with oral contraceptives when using antibiotics.
- Recommend that the patient discuss with her physician the use of an additional non-hormonal means of contraception.
- Advise the patient of the potential risk of the antibiotic’s reducing the effectiveness of the oral contraceptive.