Most cases of period pain are a normal part of your menstrual cycle and can usually be treated at home.

The period pain occurs when the muscular wall of the womb contracts. Mild contractions continually pass through your womb, but they're usually so mild that most women can't 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 (and hence oxygen supply) to your womb. 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's also producing another set of chemicals known as prostaglandins. Prostaglandins encourage the womb muscles to contract further, therefore increasing the level of pain.

It's 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 (secondary dysmenorrhoea)

Less commonly, your period pain may be caused by an underlying medical condition, such as:

• 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
• fibroids – this condition occurs when non-cancerous tumours grow in the womb, which can make your periods heavy and painful
• pelvic inflammatory disease – your womb, fallopian tubes and ovaries become infected with bacteria, leaving them severely inflamed (swollen and irritated)
• adenomyosis – the tissue that normally lines the womb starts to grow within the muscular wall of the womb, making your periods particularly painful
• intrauterine device (IUD) – this is 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 painful periods caused by an underlying condition, 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 this sort of period pain as you get older. Most affected women are aged 30-45.

Period pain caused by one of the above conditions 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.