Menstrual cramps 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 Premenstrual Syndrome (PMS) Premenstrual syndrome (PMS) is a group of physical and psychologic symptoms that start several days before and usually end a few hours after a menstrual period begins. Premenstrual dysphoric... read more (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.
Causes of Menstrual Cramps
Menstrual cramps may
Have no identifiable cause (called primary dysmenorrhea)
Result from another disorder (called secondary dysmenorrhea)
Primary dysmenorrhea usually starts during adolescence and may become less severe with age and after pregnancy. It is more common than secondary dysmenorrhea.
Secondary dysmenorrhea usually starts during adulthood unless it is caused by a birth defect.
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 Endometriosis In endometriosis, patches of endometrial tissue—normally occurring only in the lining of the uterus (endometrium)—appear outside the uterus. Why endometrial tissue appears outside the uterus... read more
: 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 Fibroids A fibroid is a noncancerous tumor composed of muscle and fibrous tissue. It is located in the uterus. Fibroids can cause pain, abnormal vaginal bleeding, constipation, repeated miscarriages... read more
: These noncancerous tumors are composed of muscle and fibrous tissue and grow in the uterus.Adenomyosis Adenomyosis In adenomyosis, tissue from glands in the lining of the uterus (endometrium) grows into the muscular wall of the uterus. The uterus becomes enlarged, sometimes doubling or tripling in size.... read more : 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 Some Causes and Features of Menstrual Cramps 
. They include
Birth defects
Cysts and tumors in the ovaries
Use of an intrauterine device Intrauterine Devices (IUDs) Intrauterine devices (IUDs) are small, flexible, T-shaped plastic devices that are inserted into the uterus. An IUD is left in place for 3, 5, 7, or 10 years, depending on the type, or until... read more
(IUD) that releases copper or a progestin (a synthetic form of the female hormone progesterone)
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.
Evaluation of Menstrual Cramps
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 check for two serious disorders that can also cause pelvic pain Pelvic Pain Pelvic pain is discomfort that occurs in the lowest part of the torso, the area below the abdomen and between the hipbones. It does not include pain that occurs externally in the genital area... read more :
An abnormally located pregnancy (ectopic pregnancy Ectopic Pregnancy Ectopic pregnancy is attachment (implantation) of a fertilized egg in an abnormal location. In an ectopic pregnancy, the fetus cannot survive. When an ectopic pregnancy ruptures, women often... read more )—that is, one not in its usual location in the uterus
Pelvic inflammatory disease Pelvic Inflammatory Disease (PID) Pelvic inflammatory disease is an infection of the upper female reproductive organs (the cervix, uterus, fallopian tubes, and ovaries). Pelvic inflammatory disease is usually transmitted during... read more
―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 or is new
Constant pain
Fever
A puslike discharge from the vagina
Sharp pain that worsens when the abdomen is touched gently or the person moves even slightly
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 menstrual cramps and the tests that may need to be done (see table Some Causes and Features of Menstrual Cramps Some Causes and Features of Menstrual Cramps ).
For a complete 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
Whether spotting occurs between periods or after sex
When symptoms occur in relation to periods
Practitioners also ask the woman the following:
How old she was when symptoms began
What other symptoms she has
What the pain is like, 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
Whether acetaminophen or nonsteroidal anti-inflammatory drugs (NSAIDs) help relieve the pain
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. She is also asked about physically or emotionally traumatic experiences, such as sexual abuse. Practitioners ask whether she has had any surgical procedures that increase the risk of pelvic pain, such as a procedure that destroys or removes the lining of the uterus (endometrial ablation).
A pelvic examination Pelvic Examination For gynecologic care, a woman should choose a health care practitioner with whom she can comfortably discuss sensitive topics, such as sex, birth control, pregnancy, and problems related to... read more is done. Doctors check the vagina, vulva, cervix, uterus, and the area around the ovaries for abnormalities, including polyps and fibroids.
Doctors also gently feel (palpate) the abdomen to check for areas of particular tenderness, which may indicate severe inflammation in the abdomen (peritonitis Peritonitis Abdominal pain is common and often minor. Severe abdominal pain that comes on quickly, however, almost always indicates a significant problem. The pain may be the only sign of the need for surgery... read more ).
Testing
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, one or more of the following tests Diagnostic Procedures Sometimes doctors recommend screening tests, which are tests that are done to look for disorders in people who have no symptoms. If women have symptoms related to the reproductive system (gynecologic... read more 
is 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
Hysteroscopy to identify problems with the cervix or uterus (but not with the ovaries)
Laparoscopy if needed
For hysterosalpingography, x-rays are taken after a substance that can be seen on x-rays (radiopaque contrast agent) 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.
For hysteroscopy, doctors insert a thin viewing tube through the vagina and cervix to view the interior of the uterus. This procedure can be done in a doctor's office or in a hospital as an outpatient procedure.
For laparoscopy, a viewing tube is inserted through a small incision just below the navel and is used to view the uterus, fallopian tubes, ovaries, and organs in the abdomen. This procedure is done in a hospital or surgical center.
If results of hysterosalpingography or sonohysterography are inconclusive, hysteroscopy or laparoscopy can be done. Both hysteroscopy and laparoscopy enable doctors to directly view structures in the pelvis. Laparoscopy enables doctors to examine all of the pelvis and reproductive organs.
Treatment of Menstrual Cramps
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
The first step toward relieving symptoms is getting enough sleep and rest and exercising regularly.
Other measures that have been suggested to help relieve the pain include a low-fat diet and nutritional supplements such as omega-3 fatty acids, flaxseed, magnesium, vitamin B1, vitamin E, and zinc. Moist heat applied to the abdomen may also help.
Drugs
If pain persists, nonsteroidal anti-inflammatory drugs (NSAIDs), such as ibuprofen, naproxen, 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 recommend also taking birth control pills Oral Contraceptives Contraceptive hormones can be Taken by mouth (oral contraceptives) Inserted into the vagina (vaginal rings) Applied to the skin (patch) Implanted under the skin read more 
that contain a progestin and a low dose of estrogen. These pills prevent the ovaries from releasing an egg (ovulation). Women who cannot take estrogen can take birth control pills that contain only a progestin.
Other hormone treatments may also help relieve symptoms. They include danazol (a synthetic male hormone), progestins (such as levonorgestrel, etonogestrel, medroxyprogesterone, or micronized progesterone, taken by mouth), gonadotropin-releasing hormone (GnRH) agonists Drugs used to treat endometriosis (such as leuprolide and nafarelin), GnRH antagonists (such as elagolix), and an IUD that releases a progestin. GnRH agonists and antagonists help relieve menstrual cramps due to endometriosis.
Drugs such as gabapentin may also help relieve symptoms. Gabapentin is an antiseizure drug that is sometimes used to reduce pain due to nerve damage.
Other treatments
If women have severe pain that persists despite treatment, doctors may do a procedure that disrupts the nerves to the uterus and thus blocks pain signals. These procedures include the following:
Injecting the nerves with an anesthetic (a nerve block)
Destroying the nerves using a laser, electricity, or ultrasound
Cutting the nerves
The procedures to disrupt the nerves may be done using a laparoscope. When these nerves are cut, other organs in the pelvis, such as the ureters, are occasionally injured.
Some alternative treatments for menstrual cramps have been suggested but have not been studied well. They include behavioral counseling (such as systematic desensitization and relaxation and pain management training), acupuncture Acupuncture Acupuncture, a therapy within traditional Chinese medicine, is one of the most widely accepted CAM therapies in the Western world. Licensed practitioners do not necessarily have a medical degree... read more , acupressure, chiropractic therapy Chiropractic In chiropractic, a manipulative and body-based practice, the relationship between the structure of the spine and the function of the nervous system is seen as key to maintaining or restoring... read more , and transcutaneous electrical nerve stimulation Nondrug Pain Treatments (application of a gentle electric current through electrodes placed on the skin). Hypnosis is being studied as treatment.
Key Points about Menstrual Cramps
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.
NSAIDs or an NSAID plus low-dose birth control pills may help relieve the pain.
