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Menstrual Cramps

by JoAnn V. Pinkerton, MD

Menstrual cramps (also called dysmenorrhea) are pains in the lowest part of the torso (pelvis) a few days before, during, or after a menstrual period. The pain tends to be most intense about 24 hours after periods begin and to subside after 2 to 3 days. The pain is usually crampy or sharp and comes and goes, but it may be a dull, constant ache. It sometimes extends to the lower back and legs.

Many women also have a headache, nausea (sometimes with vomiting), and constipation or diarrhea. They may need to urinate frequently. Symptoms of premenstrual syndrome (such as irritability, nervousness, depression, fatigue, and abdominal bloating) may persist during part or all of the menstrual period. Sometimes menstrual blood contains clots. The clots, which may appear bright red or dark, may contain tissue and fluid from the lining of the uterus, as well as blood.

Symptoms tend to be more severe if

  • Menstrual periods started at an early age.

  • Periods are long or heavy.

  • Women smoke.

  • Family members also have dysmenorrhea.


Menstrual cramps may have no identifiable cause (called primary dysmenorrhea) or may result from another disorder (called secondary dysmenorrhea). Primary dysmenorrhea usually starts during adolescence and may become less severe with age and after pregnancy. Secondary dysmenorrhea usually starts during adulthood.

Common causes

More than 50% of women with dysmenorrhea have

  • Primary dysmenorrhea

In about 5 to 15% of these women, cramps are severe enough to interfere with daily activities and may result in absence from school or work.

Experts think that primary dysmenorrhea may be caused by release of substances called prostaglandins during menstruation. Prostaglandin levels are high in women with primary dysmenorrhea. Prostaglandins may cause the uterus to contract (as occurs during labor), reducing blood flow to the uterus. These contractions can cause pain and discomfort. Prostaglandins also make nerve endings in the uterus more sensitive to pain. Lack of exercise and anxiety about menstrual periods may also contribute to the pain.

Secondary dysmenorrhea is commonly caused by

  • Endometriosis: Tissue that normally occurs only in the lining of the uterus (endometrial tissue) appears outside the uterus. Endometriosis is the most common cause of secondary dysmenorrhea.

  • Fibroids: These noncancerous tumors are composed of muscle and fibrous tissue and grow in the uterus.

  • Adenomyosis: Endometrial tissue grows into the wall of the uterus, causing it to enlarge and swell during menstrual periods.

Less common causes

There are many less common causes of secondary dysmenorrhea. They include birth defects, cysts and tumors in the ovaries, pelvic inflammatory disease, and use of an intrauterine device (IUD) that releases copper or a progestin (a synthetic form of the female hormone progesterone—see Table below and see Intrauterine Devices). IUDS that release a progestin cause less cramping than those that release copper.

In a few women, pain occurs because the passageway through the cervix (cervical canal) is narrow. A narrow cervical canal (cervical stenosis) may develop after a procedure, as when a polyp in the uterus is removed or a precancerous condition (dysplasia) or cancer of the cervix is treated. A growth (polyp or fibrosis) can also narrow the cervical canal.


Doctors usually diagnose dysmenorrhea when a woman reports that she regularly has bothersome pain during menstrual periods. They then determine whether dysmenorrhea is primary or secondary.

Doctors must distinguish dysmenorrhea from two serious disorders that can also cause pelvic pain (see Pelvic Pain):

  • An abnormally located (ectopic) pregnancy—that is, one not in its usual location in the uterus

  • Pelvic inflammatory disease―infection of the uterus and/or fallopian tubes and sometimes the ovaries

Doctors can usually identify these disorders because the pain and the other symptoms they cause typically differ from those of dysmenorrhea.

An ectopic pregnancy usually causes sudden pain that begins in a specific spot and is constant (not crampy). It may or may not be accompanied by vaginal bleeding. The pain may become severe. If the ectopic pregnancy ruptures, women may feel light-headed, faint, have a racing heart, or go into shock.

In pelvic inflammatory disease, the pain may become severe and may be felt on one or both sides. Women may also have a foul-smelling, puslike discharge from the vagina, vaginal bleeding, or both. Sometimes women have a fever, nausea or vomiting, or pain during sexual intercourse or urination.

Warning signs

In women with dysmenorrhea, certain symptoms are cause for concern:

  • Severe pain that began suddenly

  • Fever

  • A puslike discharge from the vagina

When to see a doctor

Women with any warning sign should see a doctor that day. If women without warning signs have more severe cramps than usual or have pain that lasts longer than usual, they should see a doctor within a few days. Other women who have menstrual cramps should call their doctor. The doctor can decide how quickly they need to be seen based on their other symptoms, age, and medical history.

What the doctor does

Doctors or other health care practitioners ask about the pain and the medical history, including the menstrual history. Practitioners then do a physical examination. What they find during the history and physical examination may suggest a cause of the cramps and the tests that may need to be done (see Table: Some Causes and Features of Menstrual Cramps).

For the menstrual history, practitioners ask the woman

  • How old she was when menstrual periods started

  • How long they last

  • How heavy they are

  • How long the interval between periods is

  • Whether periods are regular

  • When symptoms occur in relation to periods

Practitioners also ask the woman how old she was when symptoms began and what other symptoms she has. She is asked to describe the pain, including how severe it is, what relieves or worsens symptoms, and how symptoms interfere with her daily activities. Whether she has pelvic pain unrelated to periods is also important.

The woman is asked whether she has or has had disorders and other conditions that can cause cramps, including use of certain drugs (such as birth control pills) or an IUD.

A pelvic examination is done. Doctors check the vagina, vulva, cervix, uterus, and the area around the ovaries for abnormalities, including polyps and fibroids.

Some Causes and Features of Menstrual Cramps


Common Features*


Adenomyosis (growth of tissue that normally lines the uterus—called endometrial tissue—into the wall of the uterus)

Heavy, painful periods, vaginal bleeding between periods, pain in the lowest part of the torso (pelvis), and a feeling of pressure on the bladder and rectum

Sometimes pain during sexual intercourse

Ultrasonography or MRI of the pelvis

In women with abnormal vaginal bleeding, sometimes a biopsy

Birth defects of the reproductive tract

Sometimes genitals that feel or look abnormal or a lump in the pelvis

Sometimes hysterosalpingography (x-rays taken after a dye is injected into the uterus and fallopian tubes) or sonohysterography (ultrasonography after fluid is infused into the uterus)

Cervical stenosis (narrowing of the passageway through the cervix)

Irregular or no menstrual periods, vaginal bleeding between periods, infertility, and abdominal pain that occurs in cycles

Possibly bulging of the vagina or uterus

A doctor's examination

Sometimes ultrasonography of the pelvis

Cysts and tumors in the ovaries (cancerous or not)

Often no other symptoms

Sometimes abnormal vaginal bleeding

If cancer is advanced, sometimes indigestion, bloating, and backache

Transvaginal ultrasonography (using a handheld device inserted into the vagina)

If cancer is suspected, blood tests to measure substances produced by certain tumors

Endometriosis (patches of endometrial tissue that are abnormally located outside the uterus)

Sharp or crampy pain that occurs before and during the first days of menstrual periods


Often pain during sexual intercourse, bowel movements, or urination

A doctor's examination

Sometimes laparoscopy (insertion of a viewing tube through a small incision just below the navel)

Sometimes ultrasonography of the pelvis


Often no other symptoms

With large fibroids, sometimes pain, pressure, abnormal vaginal bleeding, or a feeling of heaviness in the pelvic area


Sometimes sonohysterography

If results are unclear, MRI

Intrauterine devices (IUDs) that release copper or, less often, a progestin (a synthetic form of the female hormone progesterone)

Pain and vaginal bleeding that often subside several months after insertion of the IUD

A doctor's examination

Usually ultrasonography of the pelvis to determine whether the IUD is correctly placed in the uterus

Pelvic congestion syndrome (chronic pain due to accumulation of blood in veins of the pelvis)

Pain that is

  • Typically dull and aching but sometimes sharp or throbbing

  • Worse at the end of the day and relieved by lying down

  • Worse during or after sexual intercourse

Often low back pain, aches in the legs, and abnormal vaginal bleeding

Occasionally a clear or watery discharge from the vagina

Sometimes fatigue, mood swings, headaches, and bloating

A doctor’s examination


Sometimes laparoscopy

Polyps in the cervix

Vaginal bleeding or discharge

A doctor's examination

Sometimes ultrasonography of the pelvis

*Features include symptoms and results of the doctor's examination. Features mentioned are typical but not always present.

MRI = magnetic resonance imaging.


Testing is done to rule out disorders that may be causing the pain. For most women, tests include

  • A pregnancy test

  • Ultrasonography of the pelvis to check for fibroids, endometriosis, adenomyosis, and cysts in the ovaries

If pelvic inflammatory disease is suspected, a sample of secretions is taken from the cervix, examined under a microscope, and sent to a laboratory to be tested.

If these tests are inconclusive and symptoms persist, other tests (see Diagnostic Procedures) are done:

  • Hysterosalpingography or sonohysterography to identify polyps, fibroids, and birth defects

  • Magnetic resonance imaging (MRI) to identify other abnormalities or, if surgery is planned, to provide more information about previously identified abnormalities

For hysterosalpingography, x-rays are taken after a dye that can be seen on x-rays (radiopaque dye) is injected through the cervix into the uterus and fallopian tubes. For sonohysterography, ultrasonography is done after fluid is infused in the uterus through a thin tube inserted through the vagina and cervix. The fluid makes abnormalities easier to identity.

If results of these tests are inconclusive, hysteroscopy or laparoscopy can be done, enabling doctors to directly view structures in the pelvis. A viewing tube is inserted into the uterus through the vagina and cervix for hysteroscopy or through a small incision just below the navel for laparoscopy.


When menstrual cramps result from another disorder, that disorder is treated if possible. For example, a narrow cervical canal can be widened surgically. However, this operation usually relieves the pain only temporarily. If needed, fibroids or misplaced endometrial tissue (due to endometriosis) is surgically removed.

When doctors diagnose primary dysmenorrhea, they reassure women that no other disorder is causing the pain and recommend general measures to relieve symptoms.

General measures

Measures that may help relieve the pain include

  • Adequate rest and sleep

  • Regular exercise

  • Heat applied to the pelvic area

  • A low-fat diet

  • Sometimes nutritional supplements such as omega-3 fatty acids, flaxseed, magnesium, vitamin E, zinc, and vitamin B 1


If pain persists, nonsteroidal anti-inflammatory drugs (NSAIDs), such as ibuprofen or mefenamic acid, may help. NSAIDs should be started 24 to 48 hours before a period begins and continued 1 or 2 days after the period begins.

If NSAIDs are ineffective, doctors may recommendbirth control pills that contain a progestin and a low dose of estrogen . These pills prevent the ovaries from releasing an egg (ovulation). Other hormone treatments may also help relieve symptoms. They include danazol (a synthetic male hormone), progestins (such as levonorgestrel, etonogestrel, or medroxyprogesterone), gonadotropin-releasing hormone agonists (synthetic forms of a hormone produced by the body), and an IUD that releases a progestin.

Other treatments

Some alternative treatments have been suggested but have not been studied well.They include acupuncture, acupressure, chiropractic therapy, and transcutaneous electrical nerve stimulation (application of a gentle electric current through electrodes placed on the skin). Hypnosis is being studied as treatment.

If women have severe pain that persists despite treatment, surgery may be recommended. For example, the nerves to the uterus may be cut to prevent pain signals from being transmitted and perceived. However, this operation occasionally injures other organs in the pelvis, such as the ureters.

Key Points

  • Usually, menstrual cramps have no identifiable cause (called primary dysmenorrhea).

  • Pain is typically crampy or sharp, starts a few days before a menstrual period, and subsides after 2 or 3 days.

  • For most women, evaluation includes a pregnancy test, a doctor's examination, and ultrasonography (to check for abnormal structures or growths in the pelvis).

  • For primary dysmenorrhea, general measures, such as adequate sleep, regular exercise, heat, and a low-fat diet, may help relieve symptoms.

  • If such measures do not help, NSAIDs or low-dose birth control pills may be used.

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