Migraine Prevention Medication Explained: Comparing CGRP Tablets & Injections

Key Takeaways

Calcitonin gene-related peptide (CGRP) drives trigeminal nerve pain signaling and meningeal blood-vessel dilation during migraine attacks.
Rimegepant dissolves under the tongue every other day for prevention (halving monthly migraine days in ~50% of trial patients) and also treats acute attacks.
Galcanezumab is a once-monthly subcutaneous injection that reduced monthly migraine days by 4 to 5 days in EVOLVE Phase 3 trials.

Unlike acute migraine painkillers taken once throbbing pain or visual aura begins, preventive migraine therapy reduces how frequently attacks happen and how severe they become (1,2). Today’s targeted CGRP (calcitonin gene-related peptide) medications represent the first drug class engineered specifically around migraine neurobiology (3,4).

Why blocking CGRP prevents migraines

During a migraine cascade, CGRP dilates meningeal blood vessels, amplifies inflammation, and relays pain along the trigeminal nerve (3). Modern preventives interrupt this cascade either by blocking the CGRP receptor with an oral wafer (rimegepant) or binding the CGRP protein directly with a monthly monoclonal antibody injection (galcanezumab).

Oral Wafer vs. Monthly Injection Compared

Feature	Rimegepant (Vydura / Nurtec ODT)	Galcanezumab (Emgality)
Mechanism	Blocks CGRP receptor	Binds directly to CGRP ligand protein
Format	Fast-dissolving sublingual wafer (no water needed)	Pre-filled subcutaneous auto-injector pen
Preventive schedule	One 75mg wafer every other day (6,7)	240mg loading dose, then one 120mg pen monthly (10)
Clinical efficacy	~50% of patients achieved ≥50% fewer migraine days (11)	~4–5 fewer monthly migraine days in EVOLVE-1/2 (8,9)
Dual acute + preventive?	Yes — licensed for both prevention and acute relief	Preventive use only
Most common side effect	Mild nausea (up to 1 in 10)	Mild injection-site redness, itching, or constipation

Choosing between an every-other-day dissolving tablet and a once-monthly pen depends on attack frequency, prior preventive history, cardiovascular profile, and personal dosing preference. Always review sudden changes in headache pattern with a licensed clinician.

References

National Institute of Neurological Disorders and Stroke. Migraine.
Shankar Kikkeri N, Nagalli S. Migraine with Aura. StatPearls; 2024.
Wattiez AS, Sowers LP, Russo AF. CGRP role in migraine pathophysiology. Expert Opin Ther Targets. 2020;24(2):91–100.
Skljarevski V, et al. EVOLVE-2 Phase 3 trial of galcanezumab. Cephalalgia. 2018.
Croop R, et al. Oral rimegepant for preventive treatment of migraine. The Lancet. 2021.

Medical Editorial Review: Reviewed by the Amble Clinical Editorial Team. This article is for educational purposes only and does not replace an individualized consultation with a licensed healthcare professional.