Can antibiotics make your period late?

Antibiotics do not make a period late. Things such as stress and illness do affect ovulation, which in turn effects periods, according to the American Pregnancy Association.

Ovulation for most women occurs approximately 12 to 16 days prior to a period, according to the American Pregnancy Association. This means that whether a period is late or early is already determined 12 to 16 days prior to the period, with the occurrence of ovulation.

Antibiotics as a whole don't modify ovulation. Rifampin is the only antibiotic known to directly affect the effectiveness of contraceptives such as birth control pills, according to Mayo Clinic.