Reviewed June 2019
Different types of period cramp pain and what they mean
Period cramps, also known as dysmenorrhea or period pains, are characteristically felt as a cramping lower abdominal pain which may spread to the lower back and legs. Other symptoms may be present such as nausea, sweating, dizziness, bloating, or tiredness. It is a very common problem — in one study of 408 young women it was reported that 84.1% suffered from menstrual pain.1 Furthermore, at least a quarter of these women experienced period pain so severe they needed medication, and were absent from school or had days off work.2 Period pain can present itself in different ways, at different times of the month. But what causes the pain and how can you tell what the pain you are experiencing means?
Period pains may be experienced at any point during the menstrual cycle. Ovulation pain occurs when the menstrual cramps begin just after the egg is released from the ovaries. This pain occurs about two weeks before menstrual bleeding is due. Because the sensation of pain is different between individuals, people can describe this pain in different ways — it can feel like an uncomfortable pressure, cramp, twinge, or sharp stab. The pain can last anything from minutes to two days and is felt on the left or right side depending on where the egg is released. The exact cause of ovulation pain is unknown. It may be that fluid or blood is released during ovulation at the same time as the egg, which may irritate the abdominal cavity, contributing to the pain. Some women may be particularly sensitive to pain compared to others, so not all women experience ovulation pain.
The more ‘typical’ period pain that is often described when people refer to their period cramps occurs just before or during menstrual bleeds. This is due to the vigorous contraction of the muscular wall layer of the womb. Womb contraction is essential for the shedding of the womb lining which causes the monthly period. When the uterine muscle contracts, it compresses the blood supply to the womb. This temporarily stops oxygen flow and so encourages the release of chemicals, such as interleukins, that trigger pain.
In addition, hormone-like chemicals called prostaglandins are released which causes the womb muscle to contract more, in order to help normal shedding of womb lining. Some women produce prostaglandins in excess, which results in more pain because of greater muscle contraction. Although it is unknown why some women feel period pains while others do not, a higher level of prostaglandins, or nerves with a lower pain threshold, may have a part to play.
What is normal?
Period pains are classified into two types: primary period pains (primary dysmenorrhea), when the underlying cause is unknown and the womb structure is normal, or secondary period pain (secondary dysmenorrhea), where there is a pelvic abnormality causing the pain.
Primary dysmenorrhea begins within the first few years from starting menstruation. An excess of prostaglandin, as described above, is thought to be responsible for the pain.3 Therefore the pain would be due to vigorous womb contractions. Each individual is different and some women naturally produce more prostaglandin than others.
Secondary dysmenorrhea usually occurs many years after the start of regular periods. There are many conditions that can cause this. Large fibroids and polyps, which are benign (non-cancerous) growths in the womb, can put pressure on other organs in the pelvis.4 This may cause a feeling of pressure or lower back discomfort. There may also be associated heavy bleeding or irregular menstrual bleeding at other times of the month. If you feel that you have these symptoms it is important to seek further advice from your GP. They will take a history and may perform a pelvic physical examination to see if they can feel for any pelvic mass or large uterus. For further tests, your GP may refer you to a gynaecologist for an ultrasound and a small telescope test to have a look inside the womb.
Endometriosis occurs when the womb lining grows in a different place other than the womb. It may cause secondary dysmenorrhea because the abnormal womb lining results in swelling and pain as it grows and bleeds into areas where there is not normally any bleeding.5 Associated symptoms may be pain during or after sex, or difficulty in getting pregnant. Adenomyosis occurs when the womb lining grows into the womb muscle, causing pain because it affects the muscle contraction and blood flow. This is often accompanied by heavy periods. If you have any of these symptoms, you should seek advice from your GP. They will take a history and may perform a pelvic physical examination to see if the uterus is enlarged. Further tests may be required in which case they may refer you to a gynaecologist for an ultrasound and/or magnetic resonance imaging (MRI) of the uterus.
Pelvic infections, caused by bacteria, irritate the womb lining and can therefore cause period pain. This pain is generally described as constant, cramping, and dull. There may be thick and foul-smelling vaginal discharge, fever, and urine infections accompanying this. Seek help from your doctor if you have any of these symptoms because there may be antibiotic treatments that would help.
Intrauterine contraceptive devices
Intrauterine contraceptive devices (IUCDs), such as the coil, may also be associated with secondary period pain, particularly in the first few months after insertion.6 The exact cause of initial cramps with IUCD insertion is not entirely clear, although it may be due to irritation of the womb lining caused by the device. If the pain is constant and severe then immediate medical help must be sought as it may be due to malposition (wrong position) of the device or, rarely, rupture of the wall of the womb.
Severe period pain, from any cause, may be associated with secondary symptoms such as nausea and vomiting. This is because pain nerves belong to the same system as nerves that supply other systems. For example, the nerves supplying the gut are also activated when the pain nerves are stimulated. So whenever severe pain is experienced there may be associated secondary symptoms such as vomiting and loose stool. Period pains often spread to the hips, back, and thighs because the nerves supplying the womb are also connected to the nerves to these areas.
These associated symptoms do not differentiate between the different types of underlying conditions because any of the secondary causes may potentially bring on these symptoms. The important thing to remember is that because secondary causes of period pain are due to pelvic pathology, any period pain that occurs in someone who does not normally get period pain should be investigated. More crucially, seek advice from your GP if your period pains are particularly severe and/or are associated with irregular or heavy periods, menstrual bleeds that occur between periods or during sex, and/or smelly vaginal discharge.
Last updated June 2019
Next update due 2021
- Grandi et al., ‘Prevalence of menstrual pain in young women: what is dysmenorrhea?’, J Pain Res, vol. 5, 2012, pp. 169-174.
- InformedHealth.org, Period pain: overview, Institute for Quality and Efficiency in Health Care, 2006. Accessed online: https://www.ncbi.nlm.nih.gov/books/NBK279324/ (accessed 24 June 2019)
- Harada, T., Dysmenorrhea and endometriosis in young women, Yonago Acta Medica, December 2013, vol 56, issue 4, pp 81-84
- NICE, Long-acting reversible contraception: the effective and appropriate use of long-acting reversible contraception, NICE Clinical Guidelines, no. 30., National Collaborating Centre for Women’s and Children’s Health, London, RCOG Press, updated 2014