<s>[INST] I am currently taking flucloxocillin for a boil that i have i know about the side affects but did not see anything about mmy period being late or missing altogether. I am 6 days late and have done a pregnancy test and it came back negative. could this be because of the antibiotic [/INST] Hi, Flucloxacillin is an antibiotic commonly prescribed to treat infections caused by susceptible bacteria like skin and wound infections. Its common side effects include nausea, vomiting, diarrhea, bloating and indigestion.  It is not known to cause delayed menstrual period. Delayed period could be due to infection, stress, change of job or place, or hormonal disorders. Hope I have answered your question. Let me know if I can assist you further.  </s>