In an 18‑year‑old woman with 2–3 months of severe dysmenorrhea (pain 7–8/10) that improves with medication, who is taking iron supplements for anemia and using a combined oral contraceptive (COC) pill, and has no vaginal discharge or other symptoms, what is the likely diagnosis and recommended management?

Likely Diagnosis and Management of Severe Dysmenorrhea in an 18-Year-Old on Combined Oral Contraceptives

This is most likely primary dysmenorrhea that is inadequately controlled by her current combined oral contraceptive regimen, and you should optimize her hormonal therapy by switching to continuous or extended-cycle COC use, adding NSAIDs during menstruation, and evaluating for secondary causes if symptoms persist beyond 3–6 months of optimized treatment. 1

Initial Assessment and Diagnosis

Primary dysmenorrhea is the most probable diagnosis given the 2–3 month history of severe menstrual pain (7–8/10) that improves with medication, absence of vaginal discharge, normal appetite, and no other systemic symptoms. 2, 1 Primary dysmenorrhea affects over 50% of menstruating women and is defined as painful menstruation without pelvic pathology. 2

However, you must rule out secondary causes before assuming this is simple primary dysmenorrhea, particularly because she is already on a COC and still experiencing severe pain. 1 The key red flags to assess include:

• Endometriosis: The leading cause of secondary dysmenorrhea in adolescents, especially when pain persists despite hormonal agents and NSAIDs. 1 In adolescents, endometriotic lesions are typically clear or red (not the classic "powder burn" lesions seen in adults) and can be difficult to identify. 1
• Pelvic examination or ultrasound findings: Any abnormalities such as ovarian cysts, uterine fibroids, adhesions, cervical stenosis, or congenital uterine malformations. 2
• Treatment adherence: Confirm she is taking her COC consistently, as inconsistent use can lead to breakthrough symptoms. 3, 4

Immediate Management Strategy

Step 1: Optimize Current COC Regimen

Switch to continuous or extended-cycle COC use rather than the standard 21/7 regimen, as continuous use reduces pain more effectively than the standard regimen in women with dysmenorrhea. 5 The evidence shows a moderate reduction in pain with continuous use (SMD -0.73). 5

• Mechanism: Continuous COC suppresses endometrial growth more completely, decreasing menstrual fluid volume and prostaglandin production, which are the primary drivers of uterine cramping. 2, 6
• Practical approach: Have her skip the placebo/hormone-free week and start a new pack immediately after finishing the active pills. 7
• Counseling point: Warn her about increased irregular bleeding during the first 3–6 months of continuous use, which is common but generally not harmful and decreases with continued use. 7, 3

Step 2: Add NSAIDs for Breakthrough Pain

Prescribe scheduled NSAIDs (not just as-needed) starting 1–2 days before expected menses and continuing through the first 2–3 days of bleeding. 8, 2

• Specific regimen: Ibuprofen 400–800 mg every 6–8 hours with food. 8
• Rationale: NSAIDs inhibit prostaglandin synthesis, directly addressing the pathophysiology of primary dysmenorrhea. 2 They are effective in reducing both pain and menstrual fluid prostaglandins. 2
• Evidence: Prostaglandin synthetase inhibitors produce significant relief from dysmenorrhea with a concomitant decrease in menstrual fluid prostaglandins. 2

Step 3: Ensure Treatment Adherence and Address Anemia

• Verify COC adherence: Review her pill-taking habits, as missed pills can lead to breakthrough ovulation and worsening dysmenorrhea. 7, 3
• Address anemia: Her iron supplementation should continue, as anemia can worsen fatigue and pain perception. Ensure she understands that COCs typically reduce menstrual blood loss, which should help improve her anemia over time. 4

Follow-Up and Escalation Plan

Timeline for Reassessment

Schedule follow-up in 3 months to assess response to optimized therapy. 1 If she does not experience clinical improvement within 3–6 months, investigate for secondary causes. 1

When to Suspect Endometriosis

Consider endometriosis if pain persists despite 3–6 months of optimized hormonal therapy plus NSAIDs, particularly if no other etiology has been identified on history, physical examination, and pelvic ultrasound. 1

• Diagnostic approach: Laparoscopy is the gold standard for diagnosis, but empiric treatment can be continued if she is improving. 2
• Important caveat: In adolescents, endometriotic lesions appear different (clear or red rather than dark "powder burn" lesions), so visualization requires an experienced surgeon. 1

Alternative COC Formulations if Current Approach Fails

If continuous COC use plus NSAIDs fails after 3–6 months:

• Consider switching progestin type: While there is probably little difference between third/fourth-generation and first/second-generation OCPs for pain improvement (RR 0.99), individual response varies. 5
• Dose consideration: There is insufficient evidence that ethinyl estradiol 20 μg is different from 30 μg for dysmenorrhea. 5
• First-line formulation: Monophasic low-dose COC containing 30–35 μg ethinyl estradiol with levonorgestrel or norgestimate is recommended as first-line. 9

Safety Monitoring and Contraindications

Adverse Effects to Monitor

COCs increase the risk of venous thromboembolism from 1 per 10,000 to 3–4 per 10,000 woman-years (still much lower than the 10–20 per 10,000 during pregnancy). 4, 9

Common adverse effects include:

• Irregular bleeding (39–60% of users vs. 18% with placebo). 4
• Headaches (RR 1.51 compared to placebo). 4
• Nausea (RR 1.64 compared to placebo). 4

Any new-onset headache or marked change in headache pattern requires clinical evaluation to rule out migraine with aura, which is a contraindication to COC use. 4

Absolute Contraindications to Verify

Ensure she does not have:

• Migraine with aura or focal neurologic symptoms. 4, 9
• History of thromboembolism or thrombophilia. 4
• Severe uncontrolled hypertension (≥160/100 mmHg). 9
• Active smoking (if she were ≥35 years old). 4

Common Pitfalls to Avoid

1. Do not assume the COC is "not working" without first optimizing the regimen to continuous use and adding scheduled NSAIDs. 5

2. Do not delay investigation beyond 6 months if symptoms persist despite optimized therapy, as endometriosis can progress if left untreated. 1

3. Do not prescribe COCs alone without NSAIDs for severe dysmenorrhea, as the combination is more effective than either alone. 2, 5

4. Do not forget to counsel about irregular bleeding with continuous COC use, as lack of counseling increases discontinuation rates. 7, 3, 9

5. Do not extend the hormone-free interval beyond 7 days if she chooses cyclic use, as this increases ovulation risk and can worsen dysmenorrhea. 9