Period pain

What causes period pain?

Period pain occurs when the muscular wall of the womb tightens (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 the womb starts to contract more vigorously to encourage the womb lining to shed away as part of your monthly period.

When the muscular wall of the womb contracts, it compresses the blood vessels lining 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.

While your body is releasing these pain-triggering chemicals, it's also producing other chemicals called prostaglandins. These encourage the womb muscles to contract more, further increasing the level of pain.

It's not known why some women experience more period pain than others. It may be that some women have a build-up of prostaglandins, which means they experience stronger contractions.

Period pain caused by a condition

Less commonly, period pain can be caused by an underlying medical condition. Doctors sometimes call this secondary dysmenorrhoea.

Period pain linked to an underlying condition tends to affect older women. Women aged 30 to 45 are most commonly affected.

Conditions that can cause period pain include:

• endometriosis – where cells that normally line the womb start to grow in other places, such as in the fallopian tubes and ovaries; these cells can cause intense pain when they shed and fall away
• fibroids – non-cancerous tumours that can grow in the womb and can make your periods heavy and painful
• pelvic inflammatory disease – where your womb, fallopian tubes and ovaries become infected with bacteria, causing them to become severely inflamed
• adenomyosis – where the tissue that normally lines the womb starts to grow within the muscular womb wall, making your periods particularly painful

An intrauterine device (IUD) is a type of contraception made from copper and plastic that fits inside the womb. It can also sometimes cause period pain, particularly during the first few months after it's inserted.

You may notice a change in your normal pattern of pain if your period pain is linked to one of the above conditions. For example, the pain may be more severe or it may last much longer than normal.

If your period pain is caused by an underlying condition, you may also experience:

• irregular periods 
• bleeding in between periods
• a thick or foul-smelling vaginal discharge
• pain during sex

See your GP if you experience any of these symptoms.

How long will my period pain last?

Period pain usually starts when your bleeding begins, although some women have pain several days before the start of their period.

The pain normally lasts 48 to 72 hours, although it can last longer. It's usually at its worst when your bleeding is heaviest.

Young girls often have period pain when they begin getting periods. Read more about starting periods.

Period pain that doesn't have an underlying cause tends to improve as a woman gets older. Many women also notice an improvement after they've had children.

How can I treat period pain?

In most cases period pain is mild enough to treat at home.

Painkillers

You can take ibuprofen and aspirin to help manage your pain.

However, don't take ibuprofen or aspirin if you have asthma or stomach, kidney or liver problems. Aspirin shouldn't be given to anyone under 16 years of age.

You could also try paracetamol, but studies have shown that it doesn't reduce pain as effectively as ibuprofen or aspirin.

If ordinary painkillers are ineffective, your GP may prescribe a stronger painkiller, such as naproxen or codeine.

Other things to try

You could also try:

• stopping smoking – smoking is thought to increase the risk of period pain
• exercise – you may not feel like exercising during a painful period, but keeping active can reduce pain; try some gentle swimming, walking or cycling
• heat – putting a heat pad or hot water bottle (wrapped in a tea towel) on your tummy may help reduce pain
• warm bath or shower – taking a warm bath or shower can relieve pain and help you relax
• massage – light, circular massage around your lower abdomen may also help reduce pain
• relaxation techniques – relaxing activities, such as yoga or pilates, may help distract you from feelings of pain and discomfort
• transcutaneous electronic nerve stimulation (TENS) – a small battery-operated device that delivers a mild electrical current to your tummy, which can help reduce pain

When should I see my GP?

See your GP if you have severe period pain or your normal pattern of periods changes – for example, if your periods become heavier than usual or irregular.

You should also see your GP if you have symptoms of secondary dysmenorrhoea, such as intense pain or heavy or painful periods.

The pill

Your GP may try you on the combined oral contraceptive pill. This can ease period pain because it thins the womb lining and reduces the amount of prostaglandin your body releases.

A thinner womb lining means the muscles of the womb don't have to contract as much when it sheds as part of your monthly menstrual cycle. Your period will also be lighter.

If the combined contraceptive pill isn't suitable for you, contraceptive implants or injections are good alternatives. The Mirena intrauterine system (IUS) can also sometimes help with painful periods.

Pelvic examination

Your GP may want to carry out a pelvic examination to help diagnose or rule out other conditions.

They'll insert gloved, lubricated fingers into your vagina to feel for any abnormalities in your womb or ovaries.

Pelvic examinations are only carried out by qualified healthcare professionals, such as GPs or gynaecologists.

The examination won't be carried out without your permission (consent). You can also choose to have a friend or relative present, or a practice nurse to act as a chaperone.

In some cases your GP may also order a pelvic ultrasound, which will clearly highlight any abnormalities.

Referral to a specialist

If your period pain hasn't been controlled after three months of treatment with painkillers or the combined contraceptive pill, your GP may refer you to a specialist.

This is for further investigations to rule out an underlying medical condition.

Further tests

To help determine the cause of your period pain, the gynaecologist may need to carry out:

• a urine or blood test
• pelvic *ultrasound* – where high-frequency sound waves are used to produce an image of the inside of your body; it's painless and will allow any abnormalities in your reproductive organs to be detected
• laparoscopy – under general anaesthetic, a small cut is made in your abdomen through which a fibro-optic telescope (laparoscope) is inserted; it can be used to look at your internal organs, as well as take samples of tissue (a biopsy)
• hysteroscopy – allows the inside of the womb to be examined using a fibro-optic telescope; it's carefully passed through your vagina and into the womb to check for abnormalities

Treating an underlying medical condition

If your period pain is caused by an underlying condition, your treatment will depend on which condition you have.

For example, pelvic inflammatory disease (PID) may require antibiotics to treat the infection, while fibroids may need to be surgically removed.

Can period pain affect fertility?

Period pain that's part of your normal menstrual cycle won't affect your fertility. However, if the cause is an underlying condition, this may affect your fertility.

For example, endometriosis and pelvic inflammatory disease can cause scarring and a build-up of tissue in your fallopian tubes, making it harder for sperm to reach and fertilise an egg.

Fibroids and adenomyosis can affect the womb and cause pain and heavy menstrual bleeding.