Merck Manual

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JoAnn V. Pinkerton

, MD, University of Virginia Health System

Reviewed/Revised Jan 2023

Dysmenorrhea is uterine pain around the time of menses. Pain may occur with menses or precede menses by 1 to 3 days. Pain tends to peak 24 hours after onset of menses and subside after 2 to 3 days. It is often crampy or a dull constant ache but may be sharp or throbbing; it may radiate to the back or legs.

Headache, nausea, constipation or diarrhea, lower back pain, and urinary frequency are common; vomiting occurs occasionally.

Sometimes dysmenorrhea is accompanied by symptoms of premenstrual syndrome or heavy menstrual bleeding and passage of blood clots.

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

Pain sensitivity with dysmenorrhea may increase susceptibility to other chronic pain conditions in later life.

Etiology of Dysmenorrhea

Dysmenorrhea can be

  • Primary (more common)

  • Secondary (due to other disorders)

Primary dysmenorrhea

Primary dysmenorrhea is idiopathic and cannot be explained by other gynecologic disorders (1 Etiology reference Dysmenorrhea is uterine pain around the time of menses. Pain may occur with menses or precede menses by 1 to 3 days. Pain tends to peak 24 hours after onset of menses and subside after 2 to... read more ). Pain is thought to result from uterine contractions and ischemia, probably mediated by prostaglandins (eg, prostaglandin F2-alpha, a potent myometrial stimulant and vasoconstrictor) and other inflammatory mediators produced in secretory endometrium and possibly associated with prolonged uterine contractions and decreased blood flow to the myometrium.

Contributing factors may include the following:

  • Passage of menstrual tissue through the cervix

  • High levels of prostaglandin F2-alpha in menstrual fluid

  • A narrow cervical os

  • A malpositioned uterus

  • Anxiety

Primary dysmenorrhea typically begins within a year after menarche and occurs almost invariably in ovulatory cycles. The pain usually begins when menses start (or just before) and persists for the first 1 to 2 days; this pain, described as spasmodic, is superimposed over constant lower abdominal pain, which may radiate to the back or thigh. Patients may also have malaise, fatigue, nausea, vomiting, diarrhea, low back pain, or headache.

Risk factors for severe symptoms include the following:

  • Early age at menarche

  • Long or heavy menstrual periods

  • Smoking

  • A family history of dysmenorrhea

Symptoms tend to lessen with increasing age and after a first pregnancy.

Secondary dysmenorrhea

Symptoms of secondary dysmenorrhea are due to pelvic abnormalities. Almost any abnormality or process that can affect the pelvic viscera can cause dysmenorrhea.

Common causes of secondary dysmenorrhea include

In a few women, pain occurs when the uterus attempts to expel tissue through an extremely tight cervical os (secondary to conization, loop electrosurgical excision procedure [LEEP], or cryotherapy). Pain occasionally results from a pedunculated submucosal fibroid or an endometrial polyp protruding through the cervix.

Risk factors for severe secondary dysmenorrhea are the same as those for primary.

Secondary dysmenorrhea usually begins during adulthood unless caused by congenital malformations.

Etiology reference

  • 1. Iacovides S, Avidon I, Baker FC: What we know about primary dysmenorrhea today: A critical review. Hum Reprod Update 21 (6):762–778, 2015. doi: 10.1093/humupd/dmv039. Epub 2015 Sep 7.

Evaluation of Dysmenorrhea

Clinicians can identify dysmenorrhea based on symptoms. They then determine whether dysmenorrhea is primary or secondary.


History of present illness should cover complete menstrual history, including age at onset of menses, duration and amount of flow, time between menses, variability of timing, and relation of menses to symptoms.

Clinicians should also ask about

  • The age at which symptoms began

  • Their nature and severity

  • Factors that relieve or worsen symptoms (including the effects of contraceptives)

  • Degree of disruption of daily life

  • Effect on sexual activity

  • Presence of pelvic pain unrelated to menses

  • Response to nonsteroidal anti-inflammatory drugs (NSAIDs)

  • History of dyspareunia or infertility (associated with endometriosis)

Review of systems should include accompanying symptoms such as cyclic nausea, vomiting, bloating, diarrhea, and fatigue.

Past medical history should identify known causes, including endometriosis, uterine adenomyosis, or fibroids. Method of contraception should be ascertained, specifically asking about IUD use.

Past surgical history should identify procedures that increase risk of dysmenorrhea, such as cervical conization and endometrial ablation.

Physical examination

Pelvic examination focuses on detecting causes of secondary dysmenorrhea. The cervix is examined for tenderness, discharge, cervical stenosis, or a prolapsed polyp or fibroid. Bimanual examination is performed to check for uterine masses and uterine consistency (a boggy uterus occurs in adenomyosis), adnexal masses, thickening of the rectovaginal septum, induration of the cul-de-sac, and nodularity of the uterosacral ligament.

The abdomen is examined for evidence of abnormal findings, including signs of peritonitis.

Red flags

The following findings are of particular concern in patients with dysmenorrhea:

  • New or sudden-onset pain

  • Unremitting pain

  • Fever

  • Purulent cervical discharge

  • Evidence of peritonitis

Interpretation of findings

Red flag findings suggest a cause of pelvic pain other than dysmenorrhea.

Primary dysmenorrhea is suspected if

  • Symptoms begin soon after menarche or during adolescence.

Secondary dysmenorrhea is suspected if

  • Symptoms begin after adolescence.

  • Patients have known causes, including uterine adenomyosis, fibroids, a tight cervical os, a mass protruding from the cervical os, or, particularly, endometriosis.

Endometriosis is considered in patients with adnexal masses, thickening of the rectovaginal septum, induration of the cul-de-sac, nodularity of the uterosacral ligament, or, occasionally, nonspecific vaginal, vulvar, or cervical lesions.


Testing aims to exclude structural gynecologic disorders. Most patients should have

  • Pregnancy testing

  • Pelvic ultrasonography

Pelvic ultrasonography is highly sensitive for pelvic masses (eg, ovarian cysts, fibroids, endometriosis, uterine adenomyosis) and can locate abnormally located IUDs.

If these tests are inconclusive and symptoms persist, hysterosalpingography or sonohysterography may be done to identify endometrial polyps, submucous fibroids, or congenital abnormalities. MRI may be required to fully characterize congenital anomalies.

If results of all other tests are inconclusive, laparoscopy may be done, particularly if endometriosis is suspected.

Treatment of Dysmenorrhea

  • Nonsteroidal anti-inflammatory drugs (NSAIDs)

  • Often hormonal contraceptives

  • Treatment of underlying disorders

If identified, disorders causing dysmenorrhea are treated (eg, surgery to remove fibroids).

General measures

Measures to improve the patient's general well-being (eg, adequate rest and sleep, regular exercise) may be helpful. . Some patients find that a heating pad (used safely to avoid burns) applied to the lower abdomen alleviates pain.

Other interventions have been suggested as potentially effective. They include a low-fat diet and nutritional supplements, such as omega-3 fatty acids, flaxseed, magnesium, vitamin B1, vitamin E, and zinc. Few data support the usefulness of these interventions; however, they are low risk.

Women with primary dysmenorrhea are reassured about the absence of other gynecologic disorders.


If pain is bothersome, NSAIDs (which relieve pain and inhibit prostaglandins) are typically tried. NSAIDs are usually started 24 to 48 hours before and continued until 1 or 2 days after menses begin.

If the NSAID is ineffective, suppression of ovulation with an estrogen/progestin contraceptive may be tried.

Other hormone therapy, such as danazol, progestins (eg, levonorgestrel, etonogestrel, depot medroxyprogesterone acetate), gonadotropin-releasing hormone agonists, or a levonorgestrel-releasing IUD, may decrease symptoms of dysmenorrhea.

Other treatments

Endometriosis may be treated pharmacologically or with surgical fulguration of lesions.

For intractable pain of unknown origin, laparoscopic presacral neurectomy or uterosacral nerve ablation has been efficacious in some patients for as long as 12 months.

Hypnosis Hypnotherapy is being evaluated as treatment. Other proposed nonpharmacologic therapies, including acupuncture Acupuncture , acupressure, chiropractic therapy Chiropractic , transcutaneous electrical nerve stimulation Electrical stimulation Treatment of pain and inflammation aims to facilitate movement and improve coordination of muscles and joints. Nonpharmacologic treatments include therapeutic exercise, heat, cold, electrical... read more , and transdermal nitroglycerin patches (which inhibit uterine contractions) have not been well-studied but may benefit some patients.

Treatment reference

Key Points

  • Most dysmenorrhea is primary.

  • Check for underlying gynecologic disorders.

  • Usually, do ultrasonography to check for structural gynecologic disorders.

  • An NSAID or an NSAID plus an estrogen/progestin contraceptive is usually effective.

Drugs Mentioned In This Article

Drug Name Select Trade
No brand name available
Alph-E-Mixed , AQUA-E, Aquasol E , Aquavite-E
AfterPill, EContra EZ, EContra One-Step, Fallback Solo, Kyleena , LILETTA, Mirena, My Choice, My Way, Next Choice, Next Choice One Dose, Norplant, Opcicon One-Step, Plan B, Plan B One-Step , Preventeza, React, Skyla, Take Action
Implanon, Nexplanon
Amen, Depo-Provera, Depo-subQ Provera 104, Provera
Deponit, GONITRO , Minitran, Nitrek, Nitro Bid, Nitrodisc, Nitro-Dur, Nitrogard , Nitrol, Nitrolingual, NitroMist , Nitronal, Nitroquick, Nitrostat, Nitrotab, Nitro-Time, RECTIV, Transdermal-NTG, Tridil
NOTE: This is the Professional Version. CONSUMERS: View Consumer Version
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