What is the recommended evaluation and management—including acute, preventive, and medication‑overuse strategies—for a patient with chronic headache occurring on 15 or more days per month for at least three months?

Chronic Headache: Evaluation and Management

Initial Diagnostic Evaluation

For a patient with headaches occurring ≥15 days per month for >3 months, immediately rule out medication overuse headache (MOH) and confirm the diagnosis of chronic migraine before initiating preventive therapy. 1

Diagnostic Criteria for Chronic Migraine

• Headache must occur on ≥15 days per month for >3 months 1
• On ≥8 days per month, headache must meet migraine criteria (unilateral, pulsating, moderate-to-severe intensity, aggravated by physical activity, with nausea/vomiting or photophobia/phonophobia) OR respond to triptan/ergot treatment 1
• Patient must have history of at least 5 prior attacks meeting migraine without aura criteria 1

Critical First Step: Screen for Medication Overuse Headache

• MOH occurs when patients use triptans, ergots, or combination analgesics on ≥10 days per month for ≥3 months 1, 2
• Simple analgesics (NSAIDs, acetaminophen) cause MOH when used ≥15 days per month for ≥3 months 1, 2
• If MOH is present, withdraw the overused medication first—preventive therapy will fail until overuse is addressed 3, 2, 4

Essential Documentation Tool

• Implement a 4-week headache diary documenting attack frequency, duration, intensity, associated symptoms, and all acute medication use 3
• This distinguishes chronic migraine from other chronic daily headache patterns and identifies medication overuse 3, 5

Management Strategy

Step 1: Address Medication Overuse (If Present)

Abruptly discontinue the overused medication—this is the cornerstone of MOH treatment. 1, 2

• Educate patients that frequent acute medication intake perpetuates chronic headache 2, 4
• Withdrawal can be performed outpatient for most patients; reserve inpatient detoxification for severe cases or opioid overuse 2
• Success rate is 50-70%, though opioid-related MOH has higher relapse rates 2

Step 2: Initiate First-Line Preventive Therapy

Start CGRP monoclonal antibodies (erenumab, fremanezumab, or galcanezumab) as first-line preventive treatment for chronic migraine. 6

• These agents reduce monthly migraine days by 2-4.8 days compared to baseline 6
• Administered as monthly subcutaneous injections with minimal systemic side effects 6
• Strong evidence from network meta-analysis of 6,979 patients demonstrating superiority in efficacy and tolerability 6
• Monitor blood pressure with erenumab due to postmarketing warnings for hypertension development or worsening 6

Step 3: Second-Line Option if CGRP Antibodies Fail or Are Unavailable

Use topiramate as second-line preventive therapy—it is the only traditional medication with randomized controlled trial evidence specifically in chronic migraine patients. 6

• Start at 25 mg daily, titrate slowly to 100-200 mg daily in divided doses over 2-3 months 6, 3
• Common side effects include cognitive slowing, paresthesias, weight loss, and kidney stones 6
• Full benefit may take 2-3 months to manifest—do not abandon therapy prematurely 6

Step 4: Consider OnabotulinumtoxinA

• FDA-approved specifically for chronic migraine (≥15 headache days/month) 6
• Evidence supports effectiveness in reducing headache burden 5
• Particularly useful for patients who fail oral preventive medications 6

Step 5: Maintain Appropriate Acute Treatment

Continue optimized acute therapy alongside preventive treatment, but strictly limit use to avoid medication overuse. 1, 7

• First-line acute treatment: NSAIDs (aspirin, ibuprofen, diclofenac) used early in headache phase 7
• Second-line: Triptans for patients not responding to NSAIDs 7
• Third-line: Gepants (rimegepant, ubrogepant) or ditans (lasmiditan) 7
• Critical pitfall: Limit triptans/ergots to <10 days per month and simple analgesics to <15 days per month to prevent MOH recurrence 1, 6

Common Pitfalls to Avoid

• Do not start preventive therapy without first addressing medication overuse—it will fail 3, 2
• Do not abandon preventive therapy before 2-3 months—full benefit takes time to manifest 6
• Do not use beta-blockers, tricyclic antidepressants, or divalproex as first-line agents for chronic migraine—evidence is primarily in episodic migraine 6
• Do not allow patients to use acute medications frequently while on preventive therapy—this perpetuates the cycle 1, 2, 4

Long-Term Management

• Chronic migraine is not static—reversion to episodic migraine occurs, but retransformation to chronic migraine can subsequently happen 1
• Maintain stability of effective treatment and monitor for changes requiring adjustment 1
• Address psychiatric comorbidities (depression, anxiety) that commonly accompany chronic migraine and impair treatment success 5
• Specialist referral is indicated for refractory cases 1