The flu itself can cause delayed menstruation, and anti-flu virus medications can also cause changes in the menstrual cycle and irregular menstruation. However, this condition does not need to be treated. By adopting a good lifestyle, getting plenty of rest, ensuring enough sleep, drinking plenty of water, keeping the room ventilated, not eating spicy and stimulating foods, having a happy mood and actively treating the flu, the patient may return to normal by the time her next period arrives. If the patient’s period is delayed for more than a week, it is recommended to exclude the possibility of pregnancy.