what causes period cramps

What causes period cramps?

From a slight ache in the lower abdomen to a pain which radiates through your whole mid-section – monthly period cramps are all-too familiar to many women.

Whether yours are a nuisance or a nightmare, read on to find out why they happen.

Why do women get period cramps?

Females of menstruating age (from around age 12 until around age 50) will experience a period approximately each month. During this time, the ovaries release the female hormones oestrogen and progesterone. These send a chemical message to the brain, which triggers an egg to release.

The uterus lining also receives instructions from these hormones - to build up and become thicker. This tissue is there for the embryo to implant to, should the egg become fertilised and the woman become pregnant.1

If the egg is not fertilised, chemicals called prostaglandins then trigger the uterus lining to shed through the vagina as a period. This lining includes cells, tissues and blood.

The uterus lining doesn’t simply shed itself and make its way through the cervix and out of the vagina. It needs a little help. This is unfortunately where the cramping part comes in.

The muscular wall of the uterus sheds its lining through a series of contractions, which encourage the lining to become loose and expel. This happens involuntary – we are not able to control this process. Unsurprisingly, these muscular contractions are what causes the cramping.

The cramping also causes a temporary restriction to the blood flow to the walls of the uterus. This triggers the release of biochemicals which contribute to the number of muscle contractions.2 Don’t just grin and bear it. Here are our top 5 remedies for painful period.

When do period cramps occur?


Most commonly, period cramps occur during the first couple of days of your period. This is when the bleeding (or the shedding of the uterus lining) is at the heaviest, therefore the contractions are strongest.

This usually lasts around 48 to 72 hours but can last longer.3

Who might be prone to period cramps?


There is not always a clear reason why some women experience severe period cramps and some women only seem to get mild ones.

However, some factors can influence the severity of the cramps. These include:4
  • if you started your periods before the age of 11 years
  • have never had children,
  • are overweight,
  • you smoke
  • you drink alcohol

What other symptoms might accompany period cramps?


Unfortunately, period cramps are sometimes accompanied by other unwelcome symptoms. These include:

  • Diarrhoea – the chemicals which trigger the contractions of the uterus can also affect the intestines. This has a laxative effect and can cause diarrhoea during menstruation for some women.5

  • Nausea – the presence of the extra prostaglandins (the chemicals which trigger muscle contractions) in the body can cause nausea in some women.6

  • Emotional symptoms – fluctuating hormone levels during a period can cause sadness, anxiety and irritability.7 That’s why you should be extra kind to yourself during this time of the month.
Period cramps shouldn’t be unbearable, but if they are severe every month, it could be a sign of a problem such as endometriosis or poly cystic ovary syndrome (PCOS). Find out more.

Last updated: 22 May 2020

2 https://www.nhs.uk/conditions/period-pain/ 3 https://www.nhs.uk/conditions/period-pain 4 https://www.webmd.com/women/guide/menstrual-pain#1 5 https://www.everydayhealth.com/digestive-health/diarrhea-and-your-period/ 6 https://www.healthline.com/health/womens-health/nausea-during-period#dysmenorrhea 7 https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3634788/ https://www.bupa.co.uk/health-information/womens-health/dysmenorrhoea
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