Can taking antibiotics cause a missed period?

Antibiotics can cause an imbalance in the production of estrogen and progesterone in the body, which in turn can delay or cause an irregular menstrual cycle, states Menstrual Cycle Calculator. Antibiotics also interfere with the body's metabolic performance and regulation of hormones, which can decrease the effectiveness of birth control.

Because antibiotics are absorbed through the liver, where estrogen and progesterone are metabolized, the hormone metabolism rate will be affected, according to Menstrual Cycle Calculator. This change in the rate of metabolism affects the amount of estrogen in the blood, which can cause an irregular cycle, as incorrect information is being sent to the pituitary gland.