More than usual menstrual pain, primary if it occurs immediately after first menstruation, and secondary if based on a gynaecological abnormality such as a uterine polyp, endometriosis or closure of the mouth of the womb. In 80 per cent of cases the disorder is primary. Pain usually begins a few hours before menstruation, and persists for one to two days. It is sited in the lower abdomen, like colic, and often associated with premenstrual tension, nausea, vomiting and diarrhoea. The pain often radiates to the vagina and the upper part of the legs. Dysmenorrhoea sometimes disappears after a first child is born. The cause is usually a high prostaglandin level, a substance secreted in all kinds of inflammation reactions. Treatment can be with aspirin if the pain is moderate, or prostaglandin inhibitors if the pain is severe. These drugs probably have side-effects, and so it is sometimes better to inhibit ovulation, by means of a specially formulated contraceptive pill. Women not wishing to use drugs can try domestic remedies such as warm baths, a hot-water bottle on the back and a warm bath for the feet. Acupuncture sometimes has good results, and can be tried for primary dysmenorrhoea.