If your period is delayed for 18 days and you are not sexually active or if pregnancy is ruled out, it is a case of irregular menstruation. Most of the menstrual irregularities are related to the imbalance of sex hormone levels in the body, and there are many factors affecting the imbalance of endocrine sex hormone levels, such as tiredness or staying up late at night, mental stress, emotional changes, or irregular diets, as well as climatic influences, or changes in the environment, which can affect the endocrine sex hormone level imbalance and influence the presence of irregularities in the menstrual cycle. Need to go to the hospital to do ultrasound, observe the thickness of the endometrium, take medication to regulate menstruation treatment, clinically can generally be taken to relax pill, wuji baifeng pill or Dingkundan, kuntai particles, motherwort particles and other proprietary Chinese medicines to regulate, if necessary, can also be used with some of the hormone medication to the joint treatment of the symptoms, such as progesterone or progesterone tablets and other medications to the symptomatic treatment. Diet should be comprehensive and diversified, at the same time, pay attention to rest, avoid labor, stay up all night, and emotionally stable, which will also help improve menstruation. The above content is for reference only, specific medication and treatment please refer to the doctor’s guidance.