Can Antibiotics Affect a Pregnancy Test? I n most cases, antibiotics will not affect a pregnancy test. These tests are designed to detect pregnancy hormones, or hCG , not estrogen. One very practical point to note are antibiotics can affect the level of estrogen (and progestin) of the oral contraceptive pills. This in turn can cause the OC pill to fail when antibiotics are used in the same time period. Antiobiotics like Rifampicin, Ampicillin and some Cephalosporins are particularly notorious for this. My mother had her period and normally came on in the morning and was off her period by the end of the day. It is rare at a young age, but this can happen to older woman. It is rare at a young age. It is used to treat or prevent bacterial infections. What do I need to tell my doctor BEFORE I take Ciprofloxacin Injection? If you have an allergy to ciprofloxacin or any other part of ciprofloxacin injection. Hi, my name is Blessing, I had unprotected sex ( with withdrawal) on Sunday 15th Nov, I’ve missed my period for 3 days now. Since Friday 23, I’ve been experiencing cramps which I usually get before my period but still no period, nor any form of spotting. Can antibiotics affect your period? When antibiotics are prescribed and taken, they can have an impact on your menstrual cycle, even if they were not prescribed specifically for an infection of the reproductive system. i.e urinary tract infections, bacterial infections and some yeast infections. 38 thoughts on “ How do antibiotics affect your period ” arifa March 14, 2017. hi i am arifa i’ve taken antibiotic and tablets exler for allargic problem and now I am one week late for my petiod. this is my first problem and first time i am late for peroid. no possiblity for pregnancy Any woman can miss a period, spot or start early at any time. Just because you are regular for 10 years or more, doesn't prevent you from ever having an irregular cycle or two. Just because you are regular for 10 years or more, doesn't prevent you from ever having an irregular cycle or two. Did you know that antibiotics could affect the menstrual cycle? Indeed, most of them can have an effect on menstrual periods, with some reporting delays. I read that anti biotic can mess up with the gut and delay period, what about having slight boiling movement up in the belly button and period feeling before the period start in a week Can anti biotics affect the way my body feel about period??.