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 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 the antibiotic rifampin.
First, let’s look at the roles that birth control pills and antibiotics play in acne treatment. Then we will consider the risks of breakthrough pregnancy when taking these two types of medication at the same time.
Birth Control Pills in Acne Treatment
The menstrual cycle influences acne. Many women report acne symptoms that coincide with their period, with an increase in acne lesions approximately 7–10 days before menstruation and then improvement once menstruation starts. These acne symptoms result from the fluctuation of several different hormones during the menstrual cycle. Each of these hormones plays a role in acne:
- Estrogens (female hormones that are present in both males and females) reduce skin oil production. Estrogens also may reduce the production of androgens (male hormones that are present in both males and females). The reduction of skin oil and androgen levels each can result in less acne.
- Androgens increase skin oil production, which can trigger acne. Progesterone (hormone present in both males and females) might play a role in the changing levels of skin oil throughout the menstrual cycle, therefore affecting acne. However, the role that progesterone plays in acne is unclear and is a matter of debate among scientists.1-3
Birth control pills prevent pregnancy, but they also regulate the menstrual cycle by stabilizing the levels of hormones during the month. This hormonal stabilization helps clear acne during the whole month.1-3
The most commonly prescribed birth control pills for acne are called combination oral contraceptives (COCs), meaning that they contain a combination of ethinyl estradiol (a synthetic form of estrogen) and progestin (a synthetic form of progesterone). In addition to preventing ovulation, the estrogen in COCs reduces the production of skin oil and may reduce androgen levels. The lower levels of skin oil and androgens lead to improved acne management. The role of progestin in acne treatment is unclear. Some studies indicate that progestin reduces androgen and skin oil levels, while other studies suggest that it worsens acne.3,4
While acne is primarily an inflammatory disease, a type of bacteria called P. acnes also plays a role. Oral antibiotics used in acne treatment kill or prevent the growth of P. acnes. At the same time, those prescribed for acne also are anti-inflammatory.
Antibiotics in Acne Treatment
According to a 2016 article in the Journal of the American Academy of Dermatology, “The [oral] antibiotics typically used in the management of acne, tetracyclines, have additional antiinflammatory actions independent of microbial killing.”4So, antibiotics treat both the bacterial and inflammatory aspects of acne.
Oral antibiotics that research has shown to be at least somewhat effective for acne are:
Despite antibiotics’ side effects, limited effectiveness, and the fact that they should be used for no longer than 3-6 months, authors of a 2016 article in the Journal of the American Academy of Dermatology wrote:
“The tetracycline class of antibiotics [tetracycline, doxycycline, and minocycline] should be considered first-line therapy in moderate to severe acne, except when contraindicated because of other circumstances (i.e., pregnancy, [the patient being less than] 8 years of age, or allergy).”4
While doctors commonly prescribe oral antibiotics for moderate-to-severe acne, oral antibiotics come with significant drawbacks:
- Antibiotics contribute to a phenomenon called antibiotic resistance, in which bacteria stops responding to an antibiotic, and that antibiotic loses its ability to kill the bacteria. Antibiotic resistance is a serious, worldwide problem that is made worse by over-prescribing antibiotics.
- Because of the danger of antibiotic resistance, oral antibiotics should not be taken for more than 3-6 months, and they should be combined with a topical (applied to the skin) treatment.
- Though serious side effects of oral antibiotics are rare, unpleasant side effects such as stomach cramps and diarrhea are common.
- Oral antibiotics are only somewhat effective for treating acne and do not completely clear the skin.4
Do Oral Antibiotics Make Birth Control Pills Less Effective?
One concern about using birth control pills and antibiotics at the same time is that antibiotics can make birth control pills less effective and lead to breakthrough pregnancy. Three large systematic reviews investigated the evidence concerning whether antibiotics make birth control pills less reliable or not. Systematic reviews are rigorous literature reviews that review 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.
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.”5
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 reported also 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.6
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.”7
Two newer but less rigorous studies came to conflicting conclusions.
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.8
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.”9
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.10
We can conclude from these studies that the only scientific evidence thus far is that rifampin reduces the reliability of birth control pills and that the question of whether other antibiotics also reduce their effectiveness or not is unanswered. However, multiple cases of breakthrough pregnancies have been reported over the years when antibiotics and birth control pills are taken simultaneously. These reports include a variety of antibiotics. Given the many cases of breakthrough pregnancies, it is prudent to employ a second method of birth control while taking antibiotics.