What are the criteria for initiating migraine prophylaxis and the recommended first- and second-line treatment options?

Migraine Prophylaxis Criteria and Treatment Algorithm

Initiate migraine prophylaxis when patients experience ≥2 days per month of migraine that adversely affects their quality of life despite optimized acute treatment. 1

Criteria for Starting Prophylaxis

The threshold for initiating preventive therapy is clear and evidence-based:

• Primary criterion: ≥2 migraine days per month with adverse impact on quality of life despite optimized acute treatment 1

Additional indications include:

• Severe debilitating headaches despite adequate acute treatment 2
• Overuse of acute medications (more than twice weekly) 3, 4
• Contraindications to or intolerance of acute treatments 2
• Prolonged, disabling attacks with poor response to abortive therapy 3
• Complicated migraine with debilitating auras (e.g., hemiplegic) 5
• History of migrainous infarction 5

The 2025 American College of Physicians guideline emphasizes that while no evidence-based thresholds exist, the ≥2 days per month criterion with functional impairment represents the consensus standard 2.

First-Line Medications

Start with beta-blockers (propranolol, metoprolol, atenolol, or bisoprolol), topiramate, or candesartan. 1

These medications have the strongest evidence base:

• Beta-blockers without intrinsic sympathomimetic activity: Propranolol and metoprolol reduce migraine days by approximately 1.27 days per month compared to placebo 6
• Topiramate: Reduces migraine days by 1.4 days per month 6
• Candesartan: Angiotensin receptor blocker with established efficacy 1

The 2025 ACP guideline prioritizes cost-effectiveness and recommends these agents before newer, more expensive options 2. The choice among first-line agents should consider:

• Comorbidities: Use beta-blockers for hypertension 4, 7
• Adverse effect profiles: Avoid topiramate if cognitive side effects or weight loss are concerns; avoid beta-blockers in athletes 3
• Contraindications: Beta-blockers contraindicated in asthma; topiramate contraindicated in pregnancy

Second-Line Medications

If first-line agents fail or are not tolerated, use flunarizine, amitriptyline, or valproate (in men only). 1

Key considerations:

• Flunarizine: Calcium channel blocker reducing migraine days by 0.44 days per month 6
• Amitriptyline: Tricyclic antidepressant reducing migraine days by 1.2 days per month; particularly useful with comorbid depression or tension-type headaches 4, 6
• Valproate: Effective but strictly contraindicated in women of childbearing potential due to teratogenicity 1

The 2025 ACP guideline also suggests venlafaxine (SNRI) as a second-line option 2.

Third-Line Medications

Consider CGRP monoclonal antibodies (erenumab, fremanezumab, galcanezumab, eptinezumab) or CGRP antagonist-gepants (atogepant, rimegepant) after failure of multiple first- and second-line agents. 1, 2

These newer agents demonstrate robust efficacy:

• CGRP monoclonal antibodies: Reduce migraine days by 1.0-3.8 days per month depending on agent and baseline frequency 6
• Atogepant: Reduces migraine days by 0.7-2.4 days per month 6

The 2025 ACP guideline positions these as third-line due to cost considerations, recommending trials of beta-blockers, valproate, venlafaxine, or amitriptyline first 2. However, these agents are particularly valuable for:

• Patients who have failed multiple oral preventives
• Those with contraindications to traditional agents
• Excellent tolerability profiles with minimal adverse effects 6

In Europe, regulatory restrictions limit CGRP-targeted therapies to patients with documented failure of other preventives 1.

Treatment Implementation

Start at low doses and titrate gradually ("start low, go slow") while monitoring for adverse effects. 5, 7

Practical approach:

• Assess efficacy after 2-3 months for oral medications 2, 3
• Assess efficacy after 3-6 months for CGRP monoclonal antibodies 1
• Switch medications if inadequate response or intolerable adverse effects occur 2
• Emphasize adherence—improvement is gradual, often apparent after the first few weeks 2

Duration and Discontinuation

After successful treatment for 6-12 months in episodic migraine, consider gradual tapering to determine if prophylaxis can be discontinued. 1, 5

• For episodic migraine: Consider tapering after 3-6 months of sustained improvement 5
• For chronic migraine: Consider tapering after 6-12 months of sustained improvement 5
• Use headache diaries to objectively track frequency and severity 2, 7

Non-Pharmacologic Adjuncts

Consider neuromodulatory devices, biobehavioral therapy (cognitive behavioral therapy, relaxation training), or acupuncture as adjuncts or alternatives when medications are contraindicated. 1

Important caveats:

• Evidence supports these interventions, though acupuncture may not be superior to sham 1
• No evidence supports physical therapy, spinal manipulation, or dietary approaches 1
• Limited evidence for melatonin, magnesium, and riboflavin 1

Critical Pitfalls to Avoid

1. Medication overuse: Address acute medication overuse (>2 days/week) before expecting prophylaxis to work 2, 3
2. Valproate in women: Never use in women of childbearing potential 1
3. Premature discontinuation: Patients must understand that efficacy takes weeks to months 2
4. Inadequate trials: Give each medication an adequate trial at therapeutic doses before declaring failure 2
5. Cost barriers: Actual patient costs vary significantly; assess economic circumstances when selecting agents 2