Nursing care
CGRP antagonists: gepants, antibody injections and how they differ from triptans
Written and reviewed by Dana Whitfield, RN, MSN · 4 min read · Updated October 2026
Short answer
CGRP antagonists block calcitonin gene-related peptide, a signal that drives migraine pain. Gepants such as rimegepant and ubrogepant are tablets; erenumab, fremanezumab and galcanezumab are injected antibodies for prevention. Unlike triptans, gepants are not contraindicated in cardiovascular disease. Nurses teach injection technique, watch for hypersensitivity, constipation and rising blood pressure, and check for medication overuse.
Where CGRP drugs fit beside triptans
During a migraine attack, the trigeminal system releases calcitonin gene-related peptide, which promotes painful inflammation around cranial vessels and the dura. CGRP antagonists interrupt this. Gepants are small oral molecules that block the receptor; some treat attacks and some also prevent them. Monoclonal antibodies are injected periodically for prevention when other options have not worked.
Triptans relieve attacks through serotonin receptors that constrict blood vessels, so they are contraindicated in coronary artery disease or uncontrolled hypertension. Gepants can be used when triptans are unsuitable for cardiovascular reasons. Unlike many acute migraine drugs, gepants are not thought to cause medication overuse headache. These contrasts are the likely exam angle.
For an exam stem, identify the role of each drug before choosing an answer. A gepant may be prescribed for an acute attack or for prevention depending on the product, whereas the injected antibodies are preventive only. A patient who expects a monthly injection to stop a migraine already in progress needs clear teaching about which medicine to use for attacks and which one is taken on schedule.
Teaching self-injection of CGRP antibodies
Erenumab, fremanezumab and galcanezumab come as prefilled pens or syringes for subcutaneous injection. For erenumab, the label advises letting the device sit at room temperature for at least 30 minutes, away from direct sunlight, before injecting, which helps deliver the full dose. Teach aseptic technique, approved sites, safe sharps disposal and what to do about a missed dose.
Watch the patient perform the first injection and use teach-back. Mild redness, pain or itching at the site is common. Hypersensitivity reactions, including rash, swelling and breathing difficulty, can occur within hours or more than a week after a dose, so patients should know that a delayed reaction still needs reporting and urgent care if breathing is affected.
Adverse effects to monitor and report
Constipation is a recognised effect of erenumab and can occasionally lead to serious complications. Ask about bowel habits before starting, encourage fluids, fibre and activity, and report severe abdominal pain, vomiting or no bowel movement. Patients already taking constipating drugs, such as opioids, need closer attention.
New or worsening hypertension has been reported with erenumab and with rimegepant, so record a baseline blood pressure and recheck during treatment. Raynaud phenomenon may also start or worsen; teach patients to report fingers turning white or blue in the cold. Rimegepant is affected by strong CYP3A4 inhibitors and inducers, so new prescriptions such as certain antifungals need pharmacist review.
Medication overuse and the wider migraine plan
Frequent use of simple analgesics, combination analgesics, triptans, ergotamine or opioids can lead to medication overuse headache, which helps convert episodic migraine into chronic migraine. Ask how many days each month the patient takes acute treatment and keep a headache diary. Preventive therapy, including CGRP antibodies, is combined with a plan for stopping overused analgesics.
CGRP drugs work alongside, not instead of, triggers management, sleep regularity, hydration and other preventive options chosen by the prescriber. When reviewing a migraine patient, document headache frequency, acute medicine days, blood pressure and bowel habit. These details show whether the preventive plan is working and whether side effects have appeared.
Worked exam-style scenario
Imagine a hypothetical patient with coronary artery disease and frequent migraine who asks for something to stop attacks. The options are a triptan, an ergot preparation, an oral gepant, or doubling daily over-the-counter analgesics. A gepant fits best because gepants do not constrict vessels and are not contraindicated in coronary disease, while triptans and ergots constrict vessels and are avoided. The prescriber still weighs the individual risk.
Doubling analgesics risks medication overuse headache and does not address frequency. In a second version, a patient on monthly erenumab reports five days without a bowel movement and cramping abdominal pain. Reporting promptly is the priority because serious constipation complications have been described, rather than simply recommending a laxative and waiting.
Sources and further reading
DailyMed: AIMOVIG (erenumab-aooe) prescribing information. Room-temperature preparation, delayed hypersensitivity, constipation with serious complications, hypertension and Raynaud phenomenon.
DailyMed: NURTEC ODT (rimegepant) prescribing information. Hypersensitivity, hypertension, Raynaud phenomenon and CYP3A4 inhibitor and inducer interactions.
MSD Manual Professional: Migraine. CGRP role, gepants and CGRP antibodies, triptan cardiovascular contraindications and medication overuse headache.
The next step on this is the same as on everything else here: answer questions and read the rationales. Our neurological practice questions are the closest set to what this page covers.
Common questions
What is the difference between a gepant and a CGRP antibody?
Gepants are oral small molecules that block the CGRP receptor and can treat or prevent attacks. CGRP antibodies are injected periodically and are used only for prevention.
Can a patient with heart disease use a CGRP antagonist?
Gepants are not contraindicated in cardiovascular disease and are an option when triptans are unsuitable, at the prescriber's judgement. Blood pressure is still monitored because hypertension has been reported.
Which side effect of erenumab should patients report?
Severe or prolonged constipation, rising blood pressure, colour change in the fingers, and any rash, swelling or breathing difficulty after an injection, even days later.