Most cases of period pain are a normal part of your menstrual cycle and can usually be treated at home. This is known as primary dysmenorrhoea.
The period pain occurs when the muscular wall of the womb (uterus) contracts. Very mild contractions continually pass through your womb, but they are usually so mild that most women cannot feel them.
During your period, the wall of your womb starts to contract more vigorously, to encourage the lining of your womb to shed away as part of your monthly menstrual cycle. When the muscular wall of your womb contracts, it compresses the blood vessels that line your womb. This temporarily cuts off the blood supply to your womb. Your blood vessels help carry oxygen to the organs and tissues within your body. Without oxygen, the tissues in your womb release chemicals that trigger pain in your body.
While your body is releasing these pain-triggering chemicals, it is also producing another set of chemicals known as prostaglandins. Prostaglandins encourage the womb muscles to contract further, therefore increasing the level of pain.
It is not yet known why some women experience more period pain than others. It has been suggested that some women may develop a build-up of prostaglandins, which means their contractions are much stronger than other women's.
Period pain caused by a medical condition
Less commonly, your period pain may be caused by an underlying medical condition. This is known as secondary dysmenorrhoea. These conditions include the following:
- Endometriosis: the cells that normally line the womb start to grow in other places within the body, usually in the fallopian tubes and ovaries. When these cells shed and fall away, they can cause intense pain. For more information, see the Health A-Z topic about endometriosis.
- Fibroids: this condition occurs when non-cancerous (benign) tumours grow in the womb. They can make your periods heavy and painful. For more information, see the Health A-Z topic about fibroids.
- Pelvic inflammatory disease: your womb, fallopian tubes and ovaries become infected with bacteria, leaving them severely inflamed (swollen and irritated). For more information, see the Health A-Z topic about pelvic inflammatory disease.
- Adenomyosis: the tissue that normally lines the womb starts to grow within the muscular wall of the womb. This extra tissue can make your periods particularly painful.
- Intrauterine device (IUD): a form of contraception made from copper and plastic, which fits inside the womb. It can sometimes cause period pain, especially in the first few months after it is inserted.
If you have secondary dysmenorrhoea, you may also have other symptoms, such as:
- irregular periods
- bleeding in between periods
- thick or foul-smelling vaginal discharge
- pain during sex
You are more likely to develop secondary dysmenorrhoea as you get older. Most women affected by secondary dysmenorrhoea are between 30 and 45 years of age.
Secondary dysmenorrhoea is normally indicated by a change in your normal pattern of pain. For example, you may find your period pain has significantly increased, or that it lasts for much longer than normal.
If you experience a significant change to your normal period pattern, see your GP to discuss your symptoms.
