Painful periods is referred to as dysmenorrhoea. The cause of the pain can be because the womb (uterus) is contracting harder than usual to dislodge the lining, or the pain may be a result of certain reproductive disorders such as endometriosis.
Many women have severe period pain. You should see a doctor if:
it's not helped by medication from the chemist
it's getting worse
you have pain when you have sex
you have abnormal bleeding (in between periods or during/after sex)
you want to get pregnant and are experiencing difficulties.
Most of the time, there isn't a serious cause for period pain. Many women find taking the contraceptive pill can be helpful with period pain.
Organisations that specialise in this area of reproductive and/or sexual health