Dysmenorrhea can range from mild to severe cramps in the lower abdomen, pulling pains at the inner thighs, backache, fainting, nausea, actual vomiting, hot and cold flushes, diarrhoea, or dizziness with headaches. Prostaglandins are hormones made in abundance during menstruation. They are produced by the uterus and other body tissues, and control the contractions of blood vessels and smooth muscle in the uterus and gastrointestinal (digestive) tract.
If a specific cause for pain is found, the dysmenorrhea is said to be secondary. If no specific cause is found, it is primary dysmenorrhea. This is not an insignificant term. Women with primary dysmenorrhea tend to be extra-sensitive to prostaglandins. The uterus contracts too strongly and cramping pains are felt. Because prostaglandin constricts the blood vessels, it can upset blood flow and cause the headaches, hot and cold flushes, diarrhea, and nausea of dysmenorrhea.
One interesting point: the male ejaculate, semen, is rich in prostaglandins. However, the uterus is protected from any undue effects. After male orgasm, semen pools in the fornices at the top of the vagina. It remains here while the sperm struggle through the cervix. The seminal plasma does not flow through into the uterus.