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Period cramps 101: Why menstrual cramps happen, and how to relieve them

Here’s what the research says about menstrual pain.

by Anna Druet, BA, and Clár McWeeney
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Top things to know

  • Menstrual cramps are most likely caused by an excess of prostaglandins—compounds that are released from the uterine lining as it prepares to be shed. They are a necessary part of the process, but in excess, they cause pain.

  • Take the edge off with a heat compress and a common anti-inflammatory pain medication, like ibuprofen

  • For prevention, consider a magnesium supplement. This mineral may be effective in lessening menstrual pain over time, and reducing the need for pain medication.

You’re probably familiar with period cramps: uterine cramps around the time of your period, which are typically felt in the abdomen, back, or thighs. You might also experience pain in the middle of your cycle during ovulation.

Menstrual cramps are very common: In Clue, about 3 in 4 people report experiencing cramps just before or during their period.

Most people first notice menstrual cramps about 6 months to a year after getting their first period (1). At first, they may come and go, and then happen in all or most cycles (as ovulation happens more frequently).

People typically feel their cramps just before or at the time when bleeding begins each cycle. They usually last about one to three days. They may start strong and feel better as the hours pass, or come and go more randomly. Cramps can be barely noticeable, or quite painful or severe (2). 1 in 10 people experience pain levels that can affect their daily activities for 1-3 days each cycle. Moderate to intense pain is more common 2 to 3 years after your first period (menarche) and usually gets better after age 20, or after pregnancy and birth (2).

Menstrual cramps that are severe are usually associated with medical conditions like endometriosis or adenomyosis. Female pain is often overlooked and/or under-treated in comparison to male pain presentation (3). It’s common for a young person suffering from severe menstrual pain not to talk about it with their doctor (4). When it comes to menstrual cramps, it’s important to advocate for yourself and communicate your pain levels to a healthcare provider. Keeping track of your pain with an app, like Clue, can be helpful.


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Getting familiar with the basics of menstrual cycle-related pain can help you understand if your pain might be something to talk to your healthcare provider about.

So what exactly causes, and relieves, cramps?

What causes period cramps?

Note: Menstrual cramps can be “primary” or “secondary”. Primary dysmenorrhea (the clinical word for painful periods) is pain caused by the period itself. Secondary dysmenorrhea is period pain with another root cause, such as a health condition like endometriosis. This article discusses primary dysmenorrhea.

Menstrual cramps are most likely caused by an excess of prostaglandins—hormone-like compounds that are released from the uterine lining (the endometrium) as it prepares to be shed. Prostaglandins help the uterus contract and relax, so that the endometrium can detach and flow out of your body. They are a necessary part of the process, but in excess, they cause pain if the uterus contracts strongly, blood flow is reduced, and the supply of oxygen to the uterus muscle tissue decreases, causing pain (5).

For most people with period cramps, it’s still unknown what predisposes them, and not others, to painful menstruation. Inflammation may play a role. The production of prostaglandins is related to inflammation, and inflamed tissue tends to produce more prostaglandins (6). People who experience more menstrual pain have also been shown to have higher levels of inflammatory markers in the blood, even after adjustment for factors related to chronic inflammation, like BMI, smoking, and alcohol consumption (7). Inflammation has also been linked to the worsening of other premenstrual symptoms, including mood changes.

People are more likely to have painful periods if they have heavy or long period bleeding, if they started menstruating early in life, or if their periods are irregular (8, 9). Other factors that have been associated with painful periods include smoking, being thin, being younger than 30, having a pelvic infection, and being sterilized (8).

Research done by Clue with Oxford University also found that Clue users with undiagnosed sexually transmitted infections (STIs) were more likely to experience certain premenstrual symptoms, including cramps, than those without STIs (10).  

How do I relieve my period cramps?

If your periods are heavy, irregular, or extremely painful, trying to find and treat the cause of your irregularities may be important for your health. Other approaches to relieving cramps, like hormonal birth control, act by preventing the building and shedding of the endometrium.

All methods of cramp relief do at least one of the following:

  • Reduce inflammation

  • Limit prostaglandin production

  • Block pain

  • Increase uterine blood flow, or

  • Treat an underlying condition, like endometriosis

Methods you might try include:

  • Medication

  • Heat

  • Transcutaneous Nerve Stimulation (TENS)

  • Diet changes

  • Supplementation

  • Stress relief

  • Quitting smoking

  • Exercise

  • Sex

  • Self-care

Medication for period cramps

Anti-inflammatory painkillers are an effective way to get relief from period pain (11). NSAIDs (non-steroidal anti-inflammatory drugs), like ibuprofen, inhibit the production of prostaglandins and inflammation. Other types of over-the counter painkillers may reduce pain, but tend to be less effective for treating menstrual cramps (12). NSAIDs are also used in reducing heavy bleeding (13).

Some people may choose to use hormonal contraceptives, such as the pill or the hormonal IUD, to relieve and prevent menstrual cramps. The synthetic hormones in these methods block ovulation, and/or prevent the typical growth and shedding of the uterine wall. This reduces or eliminates the associated build-up of prostaglandins, muscle contractions and cramps (14).

Heat for period cramps

Your grandmother’s hot water bottle is nothing to scoff at—heat is a low-fi, but tried and true method of relieving pain from menstrual cramps, and it’s cheap and has no side effects. Heat has been shown to be as effective as NSAIDs and aspirin for menstrual cramp pain (15-17).

If you want to copy the regime of one of the studies on heat and cramp relief, try using a “continuous low-level topical heat therapy” from a heated patch, pad, or water bottle.

Transcutaneous nerve stimulation and period cramps

Transcutaneous nerve stimulation (TENS) is an approved treatment for menstrual cramps. It uses a small machine to deliver low-voltage electrical current to the skin, possibly raising a user’s pain threshold and stimulating the release of the body’s natural endorphins (5).

TENS can also be combined with other methods, like heat and medication.

Diet for period cramps

As more is learned on the relationship between inflammation and period cramps, we may see recommendations for cramp-prevention diets. So far though, the data on this is limited but promising, and there are no formal clinical recommendations.

One clinical trial of 33 women with menstrual pain found that women had less menstrual pain when they followed a low fat-vegetarian diet than when they were taking a placebo dietary supplement pill (18).

A survey of 127 students found that those who reported consuming 3-4 servings of dairy had less menstrual pain than those consumed no dairy at all. This is possibly due to the intake of calcium, and maybe also vitamin D, but more research is needed—a trial on vitamin D found that very high doses were required to make a difference, which some (but not all) practitioners would consider unsafe (19-21).

Deficiency in magnesium, which is associated with anxiety and stress, has also been linked to more intense menstrual cramps (22).

Supplements for period cramps

The evidence for supplements to treat menstrual cramps isn’t well established, but you may find something that works for you if you’re open to experimenting. Check with a nutritionally-trained practitioner before taking a supplement—like any medicine, they can have side effects and interfere with levels of other nutrients in the body. Here are the top-evidenced supplements for period pain:

  • Ginger, it seems, may be as effective as common painkillers. Two systematic reviews of ginger for menstrual pain found that the root was likely more effective than a placebo for reducing pain (23,24). Clinical trials of more than 100 students with moderate to severe period pain found that pain was similarly reduced in students taking ginger, as students taking the NSAIDs Ibuprofen or mefenamic acid (25,26). One ginger group took 250mg capsules of zintoma ginger extract, from the start of their periods, and then every 6 hours, until their pain was relieved. The other took 1000mg of “ginger rhizome powder” daily (divided over 4X per day) for the first three days of their period.  

  • Magnesium (and magnesium deficiency) may play an important role for some people in dysmenorrhea (27). A systematic review that included three studies on magnesium found that it was effective in lessening menstrual pain better than a placebo and may be helpful in limiting the need for pain medication (28). Magnesium carries few side effects, but can cause loose stools, so you may need to ease into it. The three studies used different doses of magnesium, so you may want to talk to a practitioner to get a recommendation—our collaborator Lara Briden recommends starting with 300mg taken daily.

  • Zinc supplementation may be effective for a similar reason as magnesium, but more research is needed (29-32). In a randomized control trial of 120 women, the duration and severity of period cramps was significantly improved in those taking zinc, compared to those taking a placebo (32).

  • Vitamin B1 has been shown to be effective in reducing period pain. One large trial found that people taking 100 mg daily had less menstrual pain than those taking a placebo (35).

Other dietary supplements have also been researched for a possible role in easing cramps, such as vitamin E, B6, and high doses of vitamin D, as well as agnus castus, and 3+ months of fish oil (1,20,34). Results thus far are promising, or mixed.

Stress and period cramps

Stress relief may help ease period cramps in some people. Preliminary research has found that people with high levels of stress are more than twice as likely to report having painful menstruation (35). Stress during the follicular phase (the first part of the cycle) may be more likely to lead to painful menstruation than stress in the luteal cycle (the second part of the cycle, after ovulation) (35).

Smoking and period cramps

People who smoke have an increased risk of experiencing painful menstrual cramps (36). The risk increases with time, as someone continues smoking. Second-hand smoke has also been shown to increase menstrual cramps (37).

Exercise and period cramps

Exercise can likely help in easing cramps, at least in part by increasing blood flow to the abdomen. A recent meta-analysis of 11 trials found that exercise, including aerobic exercise, stretching, and yoga, is likely to help decrease the intensity of menstrual pain, and may also shorten its duration (38). Exercise can also help in reducing stress, which can contribute to pain. If doing yoga, you might try focusing on poses that stretch and stimulate the abdomen, like the cobra, cat and fish poses (39).

Sex and period cramps

There is anecdotal evidence that sex and orgasms can help with menstrual cramp relief.

Subjects of sex research pioneers Masters and Johnson reported using masturbation to relieve their cramps, and a survey of American women found that 1 in 10 reported the same (40). If exercise and TENS machines work in part by releasing endorphins and increasing blood flow, it’s plausible that sex could do the same. Additional pluses to period sex include lower chance of pregnancy and more natural lubrication (if you don’t have a tampon in just beforehand).    

Self care and period cramps

Talking about your cramps with a parent, friend, or healthcare provider seems to bring a lot of comfort for people. Other coping strategies people use are staying in bed, watching television, and other distractions like special foods, drinks, and exercise (41). Having a trusted friend or partner give you an abdominal or back massage with a good-smelling oil (lavender, perhaps?) may also be helpful, if not just really nice (42).

What kind of menstrual pain is “normal”? When should I see a healthcare provider about my cramps?

If your cramps are bad enough that they are not eased by a typical painkiller, and if they affect your ability to work, study or do any other everyday activities, it is best to talk to a healthcare provider. You should also see your healthcare provider if your cramping is suddenly or unusually severe, or lasts more than a few days.

Severe menstrual cramps or chronic pelvic pain could be a  symptom of a health conditions like endometriosis or adenomyosis. The pain experienced by people with endometriosis is different from normal menstrual cramping. Advocating for yourself about pain can be tough, but will help you to feel heard and to get the treatment you need.

Tracking pain with Clue throughout the cycle for several cycles will help you determine which symptoms, if any, recur at specific times.

Article was originally published on March 18, 2018.

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