Hi, Usually most of the antibiotics will not interfere with the menstrual cycle as per the literature available. But the clinical condition for which the antibiotic was taken can interfere with the natural cycles. Any ill-health which affects the general metabolism of the body can affect the reproductive hormonal balance and can lead to menstrual irregularity. But usually this type of irregularity can get corrected spontaneously without the need of any medication if there are no any other associated causes. Better to wait and watch for a few days. If you do not get the periods, even after one week better to consult your gynecologist once, get evaluated by clinical examination and an ultrasound, then take tablets for withdrawal bleeding. Take care. Hope I have answered your question. Let me know if I can assist you further. Regards, Dr. Sree Gouri S. R., OBGYN