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Most Doctors Are OK with Prescribing Them Together as Long as You Use a Second Method of Birth Control
The Essential Info
Doctors sometimes prescribe both birth control pills and antibiotics at the same time for women who suffer from acne, and there are cases in which antibiotics might lead to breakthrough pregnancy (pregnancy while on birth control). However, research indicates that the risk is slight.
To be on the safe side, scientists recommend using a second method of birth control while taking these two medications at the same time.
One Exception – Rifampin: An antibiotic called rifampin may reduce the efficacy of oral contraceptives, and women taking it should be aware of the risk of breakthrough pregnancy. Doctors do not prescribe rifampin for acne, but if you’re on it for any other reason, it’s best to use a backup method of contraception.
Caution: Antibiotics should be a last resort when it comes to acne treatment. Physicians understand this and prescribe them less for acne today than in the past. This is because antibiotics usually do not provide satisfying results, offer only temporary relief, and cause resistant strains of bacteria in about half of users, particularly when they are used for longer periods of time (over 3 months).
The Science
Doctors sometimes prescribe both birth control pills and oral antibiotics to treat acne in women. In addition, many women use birth control pills to prevent pregnancy and to treat other conditions, such as menstrual problems, and then their doctors prescribe oral antibiotics for acne.
Research indicates that there is an extremely small risk that taking antibiotics while on birth control pills results in breakthrough pregnancy, which occurs when a woman gets pregnant even though she uses birth control. Because of this risk, scientists recommend caution and using a second method of birth control when taking these medications at the same time, particularly when using an antibiotic called rifampin.
Let’s have a deeper look now and see what the studies say.
Do Oral Antibiotics Make Birth Control Pills Less Effective?
Five large systematic reviews investigated the evidence concerning whether antibiotics make birth control pills less reliable. Systematic reviews are rigorous literature reviews that look at multiple studies and pool the results into a combined analysis. This type of review is considered to be the highest level of evidence.
Overall, these reviews have found that there is little chance of breakthrough pregnancy when using antibiotics prescribed for acne, but particular care should be taken in women who are using an antibiotic called rifampin.1-5
Expand to read details of reviews
A 1999 review published in The Canadian Journal of Infectious Diseases concluded that rifampin, which is not prescribed for acne, is the only antibiotic that reduces estrogen levels and makes birth control pills less reliable. The authors concluded that a backup method of birth control is necessary when taking rifampin. However, they also noted that antibiotics which are used for acne, including metronidazole and tetracycline, had been associated with breakthrough pregnancies in at least three clinical cases. The authors stated, “When these agents are used, the clinician should discuss the available data with the patient and suggest a second form of birth control.”1
A 2001 review published in Obstetrics and Gynecology reported at least 30 cases of breakthrough pregnancy in women who had been taking both birth control pills and antibiotics. The antibiotic most associated with breakthrough pregnancy was rifampin. However, the study also reported 24 pregnancies in women taking tetracyclines or penicillins along with birth control pills. When the researchers pooled the results into a combined analysis, only rifampin affected the levels of estrogen and progestin. Nevertheless, there were cases of women taking other antibiotics who had experienced a decrease in these hormones that led to pregnancy. The authors concluded that doctors should be cautious when prescribing any antibiotic along with a birth control pill.2
A 2002 review published in the Journal of the American Academy of Dermatology found that rifampin was the only antibiotic that reduced estrogen levels. The authors found no evidence that other antibiotics lowered estrogen levels or increased the risk of pregnancy, even though there are clinical reports of breakthrough pregnancies when taking other antibiotics. They concluded, “Available scientific…data [does] not support the hypothesis that antibiotics (with the exception of rifampin) lower the contraceptive efficacy of oral contraceptives.”3
A comprehensive review article published in the British Journal of Obstetrics and Gynaecology in 2018 also confirmed that rifampin could lower the contraceptive efficacy of oral contraceptives. The authors reviewed 11 studies looking at women who took rifampin or rifampin-related antibiotics together with hormonal birth control. The researchers found that in 2 studies, rifampin increased the frequency of ovulation, which could make breakthrough pregnancy more likely. Additionally, in 5 studies, taking rifampin reduced estrogen and/or progestin levels, potentially making oral contraceptives less effective. Therefore, the authors concluded that women taking rifampin together with birth control pills should be aware that the efficacy of their birth control might be reduced. The scientists wrote, “Women taking COCs with rifampin should be advised of possible drug interactions affecting contraceptive effectiveness, but should not be denied use of this method.”4
The same authors published another systematic review in the American Journal of Obstetrics & Gynecology in 2018 to determine whether antibiotics other than rifampin can make hormonal birth control less effective. Rifampin is part of a class of closely related antibiotics called rifamycin antibiotics. The authors looked at 29 studies on non-rifamycin antibiotics. They found no evidence of breakthrough pregnancies caused by non-rifamycin antibiotics. In other words, according to this review, antibiotics that are typically prescribed for acne, such as doxycycline or erythromycin, are unlikely to make birth control pills less effective. The authors wrote, “Most women can expect no reduction in [hormonal contraceptive] effect with concurrent use of non-rifamycin antibiotics.” However, due to the limited quality and quantity of the available research, it is still recommended to use a second form of birth control while taking both antibiotics and oral contraceptives.5
Two other, less rigorous studies came to conflicting conclusions. While one study found that antibiotics increased the risk of breakthrough pregnancy while on birth control, the second study found no connection between taking antibiotics and breakthrough pregnancy.6,7
Expand to read details of studies
A 2012 study in Pharmacoepidemiology and Drug Safety compared 397 cases of pregnancy while on both antibiotics and birth control to 29,022 normal pregnancies. The authors concluded that the risk of pregnancy was greater in the group that had used antibiotics.6
A 2011 study in Contraception looked at 1,330 breakthrough pregnancies and concluded that there was no association between simultaneous antibiotic and birth control use. However, the authors noted, “[Because of study limitations,] findings from this study cannot rule out an elevated risk of COC failure among antibiotic users.”7
The World Health Organization stated in 2004 that, while there are suspicions that antibiotics reduce the effectiveness of birth control pills, breakthrough pregnancy rates among women taking both antibiotics and birth control pills are similar to those taking only birth control pills.8
Takeaway
One thing that is clear thus far is that rifampin reduces the reliability of birth control pills. When it comes to other antibiotics, the bulk of the evidence is pointing toward most antibiotics not interfering with birth control pills, but occasional reports of breakthrough pregnancies continue to trickle in.9 Given the many cases of breakthrough pregnancies reported over the years, it is prudent to employ a second method of birth control while taking antibiotics.
References
- Zhanel, G. G., Siemens, S., Slayter, K. & Mandell. L. Antibiotic and oral contraceptive drug interactions: is there a need for concern? Can. J. Infect. Dis. 10, 429 – 433 (1999). https://www.ncbi.nlm.nih.gov/pubmed/22346401
- Dickinson, B. D., Altman, R. D., Nielsen, N. H. & Sterling, M. L. Drug interactions between oral contraceptives and antibiotics. Obstet. Gynecol. 98, 853 – 860 (2001). https://www.ncbi.nlm.nih.gov/pubmed/11704183
- Archer, J. S. & Archer, D. F. Oral contraceptive efficacy and antibiotic interaction: a myth debunked. J. Am. Acad. Dermatol. 46, 917 – 923 (2002). https://www.ncbi.nlm.nih.gov/pubmed/12063491
- Simmons, K.B., Haddad, L.B., Nanda, K. & Curtis, K.M. Drug interactions between rifamycin antibiotics and hormonal contraception: a systematic review. BJOG 125, 804-811 (2018). https://www.ncbi.nlm.nih.gov/pubmed/29130574
- Simmons, K. B., Haddad, L. B., Nanda, K. &, Curtis, K. M. Drug interactions between non-rifamycin antibiotics and hormonal contraception: a systematic review. Am. J. Obstet. Gynecol. 218, 88-97 (2018). https://pubmed.ncbi.nlm.nih.gov/28694152/
- Koopmans, P. C., Bos, J. H. & de Jong van den Berg, L. T. Are antibiotics related to oral combination contraceptive failures in the Netherlands? A case-crossover study. Pharmacoepidemiol. Drug Saf. 21, 865 – 871 (2012). https://www.ncbi.nlm.nih.gov/pubmed/22553004
- Toh, S., Mitchell, A. A., Anderka, M., de Jong-van den Berg, L. T. & Hernandez-Diaz, S. Antibiotics and oral conceptive failure- a case-crossover study. Contraception 83, 418 – 425 (2011). https://www.ncbi.nlm.nih.gov/pubmed/21477683
- Bauer, K. L. & Wolf, D. Do antibiotics interfere with the efficacy of oral contraceptives? J. Fam. Pract. 54, 1079 – 1080 (2005). https://www.ncbi.nlm.nih.gov/pubmed/16321347
- Aronson, J. K. & Ferner, R. E. Analysis of reports of unintended pregnancies associated with the combined use of non-enzyme-inducing antibiotics and hormonal contraceptives. BMJ Evid. Based Med. 26, 112-113 (2021). https://pubmed.ncbi.nlm.nih.gov/32817012/
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