by Dr. Jerilynn C. Prior, Scientific Director, Centre for Menstrual Cycle and Ovulation Research
Painful periods are known as cramps (or in medical terms as “dysmenorrhea”). This section looks at what causes cramps, and how to control the pain yourself using inexpensive, over-the-counter medicines. They occur for almost all menstruating women at some point in their lives. For a few women, they interfere with work or school attendance. If they are severe and long-lasting it is possible that the woman has endometriosis.
Cramps are common in normal teenagers, usually decrease or go away with the first delivery (or with a miscarriage or abortion) and commonly return again when estrogen levels increase (and progesterone levels decrease) during perimenopause1.
What causes cramps?
The purpose of cramps is to help get rid of the lining of the uterus at the end of a menstrual cycle that did not lead to pregnancy. Menstrual cramps are caused by high levels of prostaglandins, a hormone that commonly signals your body that there is an injury. When prostaglandin levels are high, they increase the normal squeezing or contraction of the muscle in the wall of the uterus. After you cut yourself, it is prostaglandins that cause pain, tenderness and redness.
Prostaglandins are made within the uterus, both in the muscle and the endometrial uterine lining. Prostaglandin production increases in response to increased pressure inside the uterus and to changes in hormonal levels at the end of the menstrual cycle. Uterus pressure is increased to high levels during a period, especially in women who have not previously had a baby, a miscarriage or therapeutic abortion.
Prostaglandin levels are also increased when menstrual cycle hormones are out of balance. The current medical understanding is that cramps only occur in ovulatory cycles. In ovulatory cycles, the release of the egg is followed by the rise and fall of progesterone levels. It is thought that the normally dropping levels of progesterone before flow trigger the production of prostaglandins. What is less known is that estrogen levels similarly decrease before flow and also trigger prostaglandin release.
WHY do we believe that cramps mean ovulatory cycles?
That is not clear. The scientific literature includes little evidence about that. We likely think that because ovulation is (wrongly) assumed to be present in all regular, normal-length cycles. However, there is new information from UBC. After studying cycles over a full year in 53 healthy women who had normal-length cycles we learned that studies with normal ovulation and without ovulation had similar records of cramps. This new information suggests that anovulatory cycles are equally likely to have cramps2. In addition, normally ovulatory cycles had less cramping pain than cycles without ovulation or with short luteal phases (too short a time of progesterone production)2.
Those new results are perhaps explained by a monkey study that showed that estradiol stimulates prostaglandins, whether or not progesterone is present3. Cramps are therefore also likely related to the imbalance that occurs when estrogen levels increase, and progesterone levels are too low for the estrogen levels (as happen in the teens and during perimenopause).
How can we treat cramps?
Currently, birth control pills (combined hormonal contraceptives [CHC] called that because the same hormones can be from a pill, a patch or vaginal ring) are commonly used to treat cramps. However, CHC is not the safest option for a teenager or any woman who is not sexually active with a man and who does not need contraception. We now know that teenagers using CHC are at risk of important bone loss4. Because age and higher body weights increase the risks for blood clots5, CHC may not be appropriate or safe in women over age 35 years. CHC also increases older premenopausal women’s risks for breast cancer6 and for heart attacks and strokes7.
Every drug store or pharmacy has, on open shelves, medicines called “anti-prostaglandins” because they block the formation of prostaglandins and are commonly used to treat pain. The good news is that a common medicine used for pain, called ibuprofen, is effective for treatment of cramps8.
CeMCOR believes that the most effective way to take ibuprofen for cramps is:
- Take two tablets (400 mg) at the first hint of cramps starting
- Take one (200 mg) each time the cramps start to come back.
Note that CeMCOR has been working for several years to get funding to test this new way of taking ibuprofen for cramps. What a pharmacist will usually tell you is to take ibuprofen every 4-6 hours for cramps. But only half of women have adequate control of cramps with that way of taking ibuprofen8. Since ibuprofen keeps prostaglandins from being made in the muscle and endometrium of the uterus, CeMCOR believes to treat them, we must take ibuprofen to “stay ahead of the cramps”.
Reviewed and revised with the assistance of Dr. Sewon Bann, MD and Johnny Yip, BSc Pharm, RPh.
1. Santoro N, Brown JR, Adel T, Skurnick JH (1996). Characterization of reproductive hormonal dynamics in the perimenopause. J Clin Endocrinol Metab 81(4): 1495-501.
2. Bann S, Goshtasebi A, Prior JC. A Prospective One-Year Observational Study of Menstrual Cramps in Healthy Premenopausal Women. Poster Presentation Society for Menstrual Cycle Research Conference – Colorado Springs, CO, June 6-8, 2019.
3. Eldering JA, Nay MG, Hoberg LM, Longcope C, McCracken JA (1990). Hormonal regulation of prostaglandin production by rhesus monkey endometrium. J Clin Endocrinol Metab 71(3):596-604.
4. Goshtasebi A, Brajic TS, Scholes D, Goldberg TBL, Berenson A, Prior JC (2019). Adolescent Use of Combined Hormonal Contraception and Peak Bone Mineral Density Accrual: A meta‐analysis of international prospective controlled studies. Clin Endocrinol (Oxf) 90(4): 517-524.
5. Nightingale AL, Lawrenson RA, Simpson EL, Williams TJ, MacRae KD, Farmer RD (2000). The effects of age, body mass index, smoking and general health on the risk of venous thromboembolism in users of combined oral contraceptives. Eur J Contracept Reprod Health Care 5(4):265-74.
6. Mørch LS, Skovlund CW, Hannaford PC, Iversen L, Fielding S, Lidegaard Ø (2017). Contemporary Hormonal Contraception and the Risk of Breast Cancer. N Engl J Med 377(23):2228-2239.
7. Lidegaard Ø, Løkkegaard E, Jensen A, Skovlund CW, Keiding N (2012). Thrombotic stroke and myocardial infarction with hormonal contraception. N Engl J Med 366(24):2257-66.
8. Marjoribanks J, Ayeleke RO, Farquhar C, et al. Nonsteroidal anti-inflammatory drugs for dysmenorrhoea. Cochrane Database Syst Rev 2015(7):CD001751. Marjoribanks J, Ayeleke RO, Farquhar C, Proctor M (2015). Nonsteroidal anti-inflammatory drugs for dysmenorrhoea. Cochrane Database Syst Rev 2015(7):CD001751.