Abdominal pain during menstruation: what is important to know

Abdominal pain during menstruation is called dysmenorrhea. It is one of the most common gynecological complaints in adolescents and women of reproductive age. According to a review by American Family Physician, dysmenorrhea occurs in 50% to 90% of adolescents and women of reproductive age and remains a leading cause of missed school and work. [1]

It's important to understand that dysmenorrhea isn't always a "normal part of menstruation." For many menstruating women, the pain is moderate and manageable, but for some, it significantly reduces quality of life, disrupting sleep, school, work, physical activity, and emotional well-being. The same review indicates that up to 50% of patients miss school or work at least occasionally due to pain, and 10%-15% do so regularly. [2]

From a clinical perspective, the key distinction is between primary and secondary dysmenorrhea. Primary dysmenorrhea refers to painful periods without detectable structural pelvic pathology. Secondary dysmenorrhea refers to a specific condition causing the pain, such as endometriosis, adenomyosis, uterine fibroids, a congenital anomaly of menstrual blood flow, or pelvic inflammatory disease. [3]

This distinction has practical implications already at the first appointment. In the typical presentation of primary dysmenorrhea, current guidelines allow for treatment to be initiated immediately, without delay for invasive diagnostics or mandatory pelvic examination. The 2025 guidelines from the Canadian Society of Obstetricians and Gynecologists specifically emphasize that effective treatment is available without a mandatory preliminary pelvic examination and should not be delayed until a "definitive diagnosis." [4]

At the same time, it's important to remember that menstrual pain is sometimes the first sign of endometriosis. The World Health Organization estimates that endometriosis affects approximately 10% of women of reproductive age worldwide, and its typical symptoms include severe menstrual pain, chronic pelvic pain, heavy menstrual bleeding, infertility, bloating, and nausea. [5]

Table 1. What is usually understood by primary and secondary dysmenorrhea

Option	What does this mean?
Primary dysmenorrhea	Menstrual pain without detectable pelvic pathology
Secondary dysmenorrhea	Menstrual pain associated with disease
The most common cause of secondary dysmenorrhea in adolescents	Endometriosis
Frequent tactics for typical primary form	Empirical treatment without delay
Tactics for suspected secondary form	Further examination, visualization, gynecological route

Table basis: ACOG, AAFP and JOGC recommendations. [6]

Why does such pain occur?

In primary dysmenorrhea, the primary mechanism is believed to be excessive production of prostaglandins and leukotrienes in the endometrium. These mediators enhance uterine contractions, causing vascular spasms and transient tissue ischemia, which results in cramping pain. This explains the high effectiveness of nonsteroidal anti-inflammatory drugs, which reduce prostaglandin synthesis. [7]

Clinically, it appears quite typical: pain usually begins with the onset of menstrual bleeding, lasts from 8 to 72 hours, and is accompanied by nausea, vomiting, diarrhea, headache, weakness, lower back pain, and sleep disturbances. Primary dysmenorrhea usually begins, on average, 6-12 months after menarche, when ovulatory cycles are established. [8]

Risk factors for primary dysmenorrhea are also well described. A review by American Family Physician cites age under 30 years, earlier menarche, heavy menstrual flow, smoking, low body mass index, premenstrual syndrome, nulliparity, and certain psychosocial factors. Physical activity, age, and the use of oral contraception are also mentioned as factors associated with less severe symptoms. [9]

In secondary dysmenorrhea, the pain mechanism depends on the cause. In endometriosis, pain is associated with the presence of endometrial-like tissue outside the uterine cavity, local inflammation, scarring, and neuroinflammatory mechanisms. The World Health Organization emphasizes that endometriosis is a chronic disease in which endometrial-like tissue grows outside the uterus, causing inflammation and scar tissue formation. [10]

With adenomyosis, myoma, congenital outflow anomalies, and pelvic inflammatory diseases, pain develops along different pathways, but the clinical conclusion is the same: not all menstrual pain is created equal. When pain becomes progressive, atypical, prolonged, unilateral, or accompanied by atypical symptoms, it is necessary to look for not just a spasm, but a specific pathology. [11]

Table 2. Main mechanisms of menstrual pain

Mechanism	How does it cause pain?
Excess prostaglandins	Increases uterine contractions and vascular spasm
Transient uterine ischemia	Increases spastic pain
Local inflammation	Supports pain and tissue sensitivity
Endometriosis	Inflammation, scarring, involvement of nerve structures
Adenomyosis and myoma	Changes in the structure of the myometrium and contractility
Violation of the outflow of menstrual blood	Increased pressure and painful contractions

Table based on: AAFP, Primary Dysmenorrhea Review and World Health Organization Endometriosis Fact Sheet.[12]

Primary and secondary dysmenorrhea: how to distinguish

Primary dysmenorrhea often has a fairly recognizable pattern. The pain is cramping, localized in the lower abdomen, and begins on the day of the onset of menstruation or a few hours before. It peaks on the first day and then subsides within 2-3 days. It often recurs almost identically from cycle to cycle. [13]

Secondary dysmenorrhea is usually more concerning if symptoms change over time. It is more characterized by progressively worsening pain, later onset in life, pain that persists outside of menstruation, deep pain during or after intercourse, atypical uterine bleeding, discharge, infertility, and cyclical bowel and urinary symptoms. [14]

According to the AAFP, secondary dysmenorrhea accounts for approximately 10% of all cases, and the most common cause is endometriosis. This is especially important in adolescents: ACOG emphasizes that endometriosis is the leading cause of secondary dysmenorrhea in adolescents, and if there is no improvement after 3-6 months of proper therapy, treatment adherence should be assessed and secondary causes should be investigated. [15]

Current NICE guidelines recommend that endometriosis should be considered not only in the presence of lower abdominal pain during menstruation, but also in the presence of one or more of the following symptoms: chronic pelvic pain, menstrual pain that interferes with daily activities, deep pain during or after intercourse, cyclic pain with bowel movements, cyclic pain with urination or blood in the urine, and infertility associated with these symptoms.[16]

NICE specifically notes that a first-degree relative with endometriosis increases the likelihood of the disease. Therefore, a family history is not a formality but an important part of the initial triage process. It also recommends keeping a pain and symptom diary, as it helps more accurately assess the frequency, severity, and impact of pain on daily life. [17]

Table 3. How primary dysmenorrhea differs from secondary dysmenorrhea

Sign	Primary dysmenorrhea	Secondary dysmenorrhea
Onset of symptoms	Most often soon after the establishment of ovulatory cycles	May start later or progress rapidly
The nature of pain	Typically cramping, during the first 1-3 days of menstruation	Often longer, heavier, and can extend beyond menstruation
Flow	Similar from cycle to cycle	Often gets worse over time
Common associated symptoms	Nausea, weakness, diarrhea, lower back pain	Pain during intercourse, infertility, abnormal bleeding, intestinal and urinary symptoms
A common cause	Prostaglandin-mediated uterine contractions	Endometriosis, adenomyosis, myoma, congenital anomalies, infection

Table basis: AAFP, ACOG and NICE. [18]

Symptoms and red flags

The typical pain associated with primary dysmenorrhea is cramping pain in the lower abdomen, sometimes radiating to the lower back and inner thighs. It may be accompanied by nausea, vomiting, headache, diarrhea, fatigue, and sleep disturbances. An important practical point: in the primary form, this pain should still fall within the "menstrual window" and not persist beyond it. [19]

Secondary dysmenorrhea is suspected if the pain intensifies from cycle to cycle, is accompanied by intermenstrual bleeding, very heavy periods, pain during intercourse, pain during bowel movements, infertility, or if conventional therapy is ineffective. This development was already hinted at in the original article, but in modern practice it should be described as clearly as possible.

Endometriosis is particularly characterized by pain that impacts daily life. NICE explicitly uses menstrual pain as a diagnostically significant sign, as it impairs quality of life and interferes with daily activities. The World Health Organization adds that endometriosis can affect sexuality, bowel function, bladder function, and mental health, including anxiety and depression. [20]

There are also situations that require not only a routine gynecological examination but also an urgent medical assessment. These include sudden, severe, one-sided pain, fainting, severe weakness, fever, unusual discharge, suspected pregnancy, a sharp increase in pain that is unlike usual, as well as pain accompanied by an acute abdomen. In such cases, it is necessary to rule out not only gynecological but also surgical causes. [21]

A particular pitfall in adolescents is that a normal ultrasound examination does not rule out endometriosis. NICE clearly states that a normal examination and ultrasound examination cannot rule out endometriosis, and ACOG emphasizes that in adolescents with persistent, clinically significant pain despite nonsteroidal anti-inflammatory drugs and hormonal therapy, endometriosis should continue to be taken seriously. [22]

Table 4. Red flags for period pain

Sign	Why is it important?
Progressive increase in pain	Increases the likelihood of a secondary cause
Pain during intercourse	Suspected endometriosis and other pelvic pathology
Intermenstrual bleeding	Requires a search for an organic cause
Very heavy periods	Possible adenomyosis, myoma, concomitant anemia
Pain when passing stool or urinating	Suspected deep endometriosis
No effect from therapy for 3-6 months	A reassessment of diagnosis and adherence is needed.
Fever, fainting, unusual discharge, suspicion of pregnancy	Urgent in-person assessment required

Table basis: AAFP, ACOG and NICE. [23]

Diagnostics

Diagnosis begins with a detailed medical history, not a long list of tests. The 2025 JOGC guidelines list a thorough menstrual, pain, and gynecological history among the first steps, including the onset of symptoms, their severity, and response to previous treatments. The AAFP also emphasizes that questioning should include menstrual history, family history, surgeries, associated symptoms, and any over-the-counter methods already used. [24]

If the history is consistent with primary dysmenorrhea, current guidelines allow for empirical treatment to be initiated without a mandatory pelvic examination. The AAFP states that a pelvic examination is unnecessary for patients with symptoms typical of primary dysmenorrhea. JOGC 2025 further states that therapy can be initiated without a preliminary pelvic examination, and treatment should not be delayed to confirm the diagnosis. [25]

Another situation arises if the patient is sexually active, pregnancy is suspected, or signs of secondary dysmenorrhea are present. In this case, the initial evaluation should include a pregnancy test, and further examination and imaging are tailored based on symptoms. The AAFP specifically recommends a pregnancy test for sexually active patients and a pelvic examination with ultrasound if secondary dysmenorrhea is suspected. [26]

A recent and particularly important shift was introduced by the 2024 NICE update: transvaginal pelvic ultrasound is now recommended for all patients with suspected endometriosis, even if a pelvic or abdominal examination is normal. If a transvaginal examination is unsuitable or rejected, a transabdominal pelvic ultrasound may be considered. However, a normal examination and ultrasound do not rule out endometriosis and do not preclude a possible referral to a gynecologist. [27]

If deep infiltrating endometriosis is suspected, NICE recommends considering a specialized transvaginal ultrasound or pelvic magnetic resonance imaging (MRI), with these scans planned and interpreted by a specialist experienced in gynaecological imaging. This is important because a routine MRI scan in this scenario is less valuable than a properly targeted, expert examination. [28]

Laparoscopy remains an important method for confirming the diagnosis, but modern logic no longer requires referring every patient for surgery before treatment. NICE allows laparoscopy if endometriosis is suspected, even with normal ultrasound or magnetic resonance imaging results, if clinical suspicion remains. At the same time, NICE specifically recommends against using the serum marker CA 125 for diagnosing endometriosis. [29]

Table 5. Step-by-step diagnostic route

Clinical scenario	What do you usually do first?
Typical primary dysmenorrhea	Detailed history and empirical treatment
Sexual activity or risk of pregnancy	Pregnancy test
Signs of secondary dysmenorrhea	Pelvic examination and ultrasound
Suspected endometriosis	Transvaginal ultrasound examination of the pelvis
Suspected deep endometriosis	Specialized ultrasound or magnetic resonance imaging
Persistent suspicion with normal imaging	Consideration of laparoscopy

Table basis: AAFP, NICE and JOGC 2025. [30]

Treatment

Treatment depends on the typical presentation of primary dysmenorrhea and whether there is reason to suspect a secondary cause. For the typical primary form, nonsteroidal anti-inflammatory drugs (NSAIDs) remain the first-line treatment. The AAFP notes that they are superior to placebo and acetaminophen and are considered first-line therapy because they reduce prostaglandin synthesis. [31]

A key practical consideration is not only the choice of medication, but also timing. Guidelines recommend starting NSAIDs 1-2 days before the expected onset of menstruation and continuing them regularly for the first 2-3 days of bleeding, when prostaglandin levels are highest. In real life, it is precisely incorrect timing that often creates the false impression that medications "don't work." [32]

Hormonal therapy is another first-line option or adjunct to NSAIDs, particularly if contraception is needed or if the pain response is insufficient. According to the AAFP, combined estrogen-progestin contraceptives are effective as a first-line alternative or adjunct to NSAIDs. Continuous regimens often provide faster and more pronounced pain relief than cyclical regimens. [33]

If estrogen is contraindicated or poorly tolerated, progestogen-only options are available. The AAFP states that progestogen-only methods, including pills, injections, implants, and the levonorgestrel intrauterine system (IUS), are also acceptable for the treatment of dysmenorrhea. A systematic review cited by the AAFP shows that the IUS is effective for both primary dysmenorrhea and dysmenorrhea associated with endometriosis. [34]

Non-pharmacological treatments do not replace primary therapy for severe pain, but they can be a useful adjunct. The AAFP notes evidence supporting physical activity, high-frequency transcutaneous electrical nerve stimulation, heat therapy, and pressure point self-massage. A Cochrane review found pain reduction in physical activity, particularly with 45-60 minutes of exercise at least three times a week. [35]

If pain is associated with endometriosis, the approach changes. NICE recommends a short trial course of analgesics, as well as hormonal treatment, such as combined pills or progestogen, to reduce pain. NICE specifically emphasizes that hormonal therapy for endometriosis reduces pain and does not have a permanent negative impact on future fertility. If initial approaches are ineffective, the patient is referred to a gynecological service, and in cases of endometrioma, deep endometriosis, or extrapelvic disease, to a specialized center. [36]

For second-line endometriosis, current guidelines already include gonadotropin-releasing hormone agonists and antagonists, as well as surgical approaches for selected patients. In 2025, NICE added references to gonadotropin-releasing hormone antagonist technologies for adults of reproductive age after previous medical or surgical treatment. However, this is no longer the initial step for routine menstrual pain, but a later, specialized level of care. [37]

Table 6. Main treatment options

Approach	When it is especially appropriate
Nonsteroidal anti-inflammatory drugs	First line for typical primary dysmenorrhea
Combined hormonal contraceptives	First line or adjunct to pain relief
Progestogen-only methods	In case of contraindications to estrogen or poor tolerance
Levonorgestrel intrauterine system	When long-term pain control and contraception are needed
Physical activity, heat, transcutaneous electrical nerve stimulation	As an adjunct to the main therapy
Specialized treatment for endometriosis	If initial therapy is ineffective or a secondary cause is confirmed

Table base: AAFP, NICE and AAFP on endometriosis. [38]

When is urgent help needed, what is the prognosis, and what can be done for prevention?

Urgent medical attention is needed if the pain suddenly becomes significantly more severe than usual, severe one-sided pain develops, fainting occurs, pregnancy is suspected, fever occurs, unusual discharge occurs, severe weakness occurs, or symptoms do not fit the usual menstrual pattern. In these cases, you should not wait "until your period ends," as acute gynecological or surgical conditions may be concealed under the guise of menstrual pain. [39]

The prognosis for primary dysmenorrhea is often favorable if treatment is chosen correctly and started promptly. However, the problem is that dysmenorrhea is often underdiagnosed and treated incorrectly. The 2025 Canadian guidelines explicitly emphasize that menstrual pain is often undertreated or unfairly undervalued, and without treatment, it can develop into chronic pain in some patients. [40]

With secondary dysmenorrhea, the prognosis depends on the cause. For endometriosis, early diagnosis is important, as the World Health Organization notes a typical diagnostic delay of 4-12 years, while the AAFP estimates a delay of up to 4-10 years. This delay worsens quality of life, increases the risk of chronic pain, and prolongs the time to adequate treatment. [41]

Among practical self-help measures, the most sensible include early and appropriate use of nonsteroidal anti-inflammatory drugs, keeping a pain diary, physical activity, heat therapy, and prompt discussion of hormonal therapy if pain interferes with normal life. But something else is fundamentally important: if the pain is uncontrolled, progresses, or is accompanied by red flags, the task is no longer to endure it more or change the painkiller, but to change the diagnostic pathway. [42]

FAQ

Does period pain always mean illness?

No. With primary dysmenorrhea, severe pain can occur even without structural pelvic pathology. However, if the pain increases, changes in nature, or does not respond well to treatment, a secondary cause should be sought. [43]

When can treatment be started without extensive examination?

If the history is typical for primary dysmenorrhea, empirical treatment can be initiated immediately. Current guidelines do not recommend delaying therapy until invasive diagnostic testing or mandatory pelvic examination for typical presentations. [44]

How long should a diagnosis be revised if treatment is not helping?

In adolescents, ACOG recommends assessing adherence and seeking secondary causes if clinical improvement is not seen within 3-6 months of initiating therapy.[45]

Does a normal ultrasound rule out endometriosis?

No. NICE clearly states that a normal examination and ultrasound scan do not rule out endometriosis, and referral to a gynaecologist may still be necessary.[46]

Is it necessary to determine CA 125 if there is a suspicion of endometriosis?

No. NICE does not recommend the use of serum CA 125 for the diagnosis of endometriosis.[47]

What is most often helpful for typical primary dysmenorrhea?

Most often, nonsteroidal anti-inflammatory drugs (NSAIDs), started early and taken at the correct time, as well as hormonal therapy, if indicated and tolerated, are helpful. Physical activity, heat, and transcutaneous electrical nerve stimulation (TENS) may also be helpful. [48]

Key points from experts

Margaret Burnett, MD, and Madeleine Lemyre, MD, authors of the Canadian Guidelines for Primary Dysmenorrhea, formulate the most important current thesis: menstrual pain should not be discounted, and its treatment should not be delayed until invasive diagnostic testing is performed. Their guidelines emphasize that therapy can be initiated without a mandatory pelvic examination, and if symptoms persist, further investigation can be performed. [49]

Kathryn A. McKenna, MD, MPH, and Corey D. Fogleman, MD, authors of the American Family Physician review, emphasize primary care: for typical primary dysmenorrhea, nonsteroidal anti-inflammatory drugs remain the first line of treatment; hormonal therapies can be used as an alternative or adjunct; and if secondary dysmenorrhea is suspected, a pelvic examination and ultrasound are necessary. This is a practical and very useful algorithm for an outpatient article. [50]

Rina Edi, MD, and Terri Cheng, MD, authors of a review on endometriosis, emphasize another key point: endometriosis is increasingly being diagnosed clinically and by imaging, not just after immediate laparoscopy. They also show that transvaginal ultrasound remains the initial imaging modality, and hormonal therapy remains the mainstay of symptom control in many patients. [51]

The American College of Obstetricians and Gynecologists' Committee on Adolescent Gynecology emphasizes a particularly important point for young adults: persistent dysmenorrhea in adolescents that is unresponsive to nonsteroidal anti-inflammatory drugs and hormonal therapy should raise concerns about endometriosis, which is the leading cause of secondary dysmenorrhea in this age group. This point is especially valuable because adolescent pain is often dismissed as "just heavy periods." [52]

In its 2024 update, NICE effectively cemented another important clinical shift: a patient with suspected endometriosis should not be "reassured" simply because an examination or routine ultrasound scan turned out normal. The modern pathway requires thinking more broadly about the disease, offering imaging earlier, and, if necessary, referring to specialists even when the "visual" picture is less than ideal. [53]