Do Antibiotics Affect Progesterone?

In our latest question and answer, the pharmacist discusses whether or not antibiotics like amoxicillin affect progesterone.

Jan 10, 2018

Kayla asked

One doctor prescribed Amoxicillin for a sinus infection and one doctor prescribed Progesterone Micronized to stop my menstrual cycle (I have PCOS). Would the Amoxicillin affect Progesterone like a birth control? I really don't want to wait to take one of them, because my sinus infection is really bad and has been going on for 2 months now and my period has been going on for 8 I'd really like to take both meds at the same time if possible. Is that a good idea?


Amoxcillin does not have a significant effect on micronized progesterone (brand name Prometrium) and there is no reported or listed interaction between them. In fact, most data points to the vast majority of antibiotics not having any affect on progesterone levels in those taking it as a prescription. While there is some controversy regarding whether or not antibiotics affect hormonal birth control, you can feel confident that there is no interaction in your case.

Antibiotic Progesterone Interaction

Most studies show that only one class of antibiotics (rifamycin) definitively decrease hormone levels from combined hormonal contraceptive pills (i.e. ones the contain an estrogen and progestone). In addition, rifamycin antibiotics have shown to affect progesterone only products such as Prometrium, intra-vaginal progesterone products and injectable progesterone.

While not conclusive, current data suggests that no other class of antibiotic is associated with contraceptive failure or significant alteration of hormone blood levels when taken with oral hormonal contraceptive pills.

In studies that did have a small number individuals experience lowered hormone levels, it appeared that estrogen levels are more affected than progesterone levels. All in all, non-rifamycin antibiotics (such as amoxicillin) do not appear to significantly affect progesterone levels, if at all. 

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