CGRP Side Effects: What Studies Report

What the term refers to in the published literature

Calcitonin gene-related peptide (CGRP) is an endogenous neuropeptide, and reviews described its role in migraine pathophysiology and its use as a therapeutic target rather than as an administered compound (PMID 32003253). For that reason, almost all adverse-event data indexed under "CGRP" come from trials of drugs that block the peptide or its receptor: monoclonal antibodies against CGRP or the CGRP receptor, and small-molecule receptor antagonists called gepants, both of which a 2024 handbook chapter described in the context of migraine prevention (PMID 38307640). This page is for educational purposes only and is not medical advice; consult a licensed physician for any question about a medicine, a symptom or a treatment decision.

What kinds of studies reported adverse events

The adverse-event record for this class came mainly from randomised placebo-controlled prevention trials in adults with episodic or chronic migraine, pooled afterwards in systematic reviews and network meta-analyses; a 2023 Cephalalgia systematic review and network meta-analysis specifically examined the safety and tolerability of CGRP-pathway monoclonal antibodies and gepants in migraine prevention (PMID 36786548). A separate 2023 network meta-analysis in The Journal of Headache and Pain compared migraine preventive drugs against one another for effectiveness and tolerability outcomes, placing the CGRP-targeting agents alongside older oral preventives (PMID 37208596). Narrative reviews and society position papers summarised the same trial base without re-pooling it, including a 2025 Lancet review of CGRP-targeted therapy (PMID 40121062) and the American Headache Society position statement update on CGRP-targeting therapies (PMID 38466028).

Where this page describes an event as "reported", that means a cited review, trial summary or meta-analysis named the event in the source listed in the same sentence. Several of the sources summarised tolerability narratively rather than as percentages, so numeric frequencies are not reproduced here when the cited source did not present them at that level (PMID 38307640).

Adverse events by body system: What Studies Report

Gastrointestinal: What Studies Report

Constipation was among the events most consistently named in safety summaries of CGRP-pathway monoclonal antibodies, and the 2023 Cephalalgia network meta-analysis assessed tolerability and adverse-event outcomes across these agents and gepants in prevention trials (PMID 36786548). Nausea was described in connection with gepants in reviews of the two drug families used for migraine prevention (PMID 38307640). A 2025 Lancet review of CGRP-targeted therapy discussed the gastrointestinal tolerability profile alongside the broader clinical role of the class (PMID 40121062).

Injection site and skin: What Studies Report

Injection-site reactions were reported for the subcutaneously administered monoclonal antibodies in prevention trials pooled by the 2023 safety network meta-analysis (PMID 36786548). Reviews of migraine treatment that covered the antibodies also noted local reactions as a route-related finding not shared by the orally administered gepants (PMID 38307640). Hypersensitivity reactions were discussed as a labelled concern for the antibody class in a 2025 review of CGRP-targeted therapy (PMID 40121062).

Cardiovascular and blood pressure: What Studies Report

Because CGRP is a vasodilator, reviews treated vascular effects as a mechanistic question as well as an adverse-event question, and a 2020 review set out the peptide's vascular biology in the context of therapeutic targeting (PMID 32003253). Blood-pressure elevation reported after marketing was discussed in the 2025 Lancet review of the class (PMID 40121062), and the American Headache Society position statement update addressed safety considerations when the agents were positioned as a first-line preventive option (PMID 38466028). A 2025 Neurology review examined CGRP-targeted migraine therapies specifically in patients with vascular risk factors or stroke and described the state of evidence for those populations (PMID 40537071).

Hepatic: What Studies Report

Liver-related findings belong mainly to the earlier history of small-molecule CGRP receptor antagonists, and a 2018 Nature Reviews Neurology review traced the development of CGRP-targeting migraine therapies from bench to clinic, including why some early compounds did not continue (PMID 29691490). The 2025 Lancet review revisited the hepatic question for currently used gepants as part of its account of the class's current role (PMID 40121062), and the 2023 network meta-analysis of safety and tolerability assessed discontinuation and adverse-event outcomes for gepants and antibodies together (PMID 36786548).

General, neurological and respiratory: What Studies Report

Fatigue, somnolence and nasopharyngitis appeared among the non-specific events catalogued in prevention trials that the 2023 Cephalalgia analysis pooled for tolerability outcomes (PMID 36786548). Comparative work placed these events next to the side-effect burden of older oral preventives such as topiramate and beta-blockers, which the 2023 comparative-effectiveness network meta-analysis evaluated in the same framework as the newer agents (PMID 37208596). A 2022 treatment update reviewed acute and preventive headache options, including the CGRP-targeting drugs, within general clinical practice (PMID 36636337).

Summary table of reported event categories

Vascular risk and stroke populations: What Studies Report

Randomised prevention trials generally enrolled adults without major cardiovascular disease, which is why a 2025 Neurology review was devoted to what was and was not known about CGRP-targeted migraine therapies in patients with vascular risk factors or stroke (PMID 40537071). That review described the evidence base for those populations as an area still being defined rather than settled (PMID 40537071). The 2025 Lancet review likewise framed long-term and special-population safety as part of the future perspectives for the class rather than as closed questions (PMID 40121062).

Where structured adverse-event data are limited

Several categories of use have no dedicated pooled adverse-event dataset in the sources cited here. Pregnancy, long-term exposure beyond trial duration, and use in children and adolescents were not the subject of any of the verified safety analyses on this page; the 2023 Cephalalgia review addressed prevention trials in adults with migraine (PMID 36786548). Non-migraine uses of CGRP-targeting drugs, and any use of CGRP itself as an administered substance, were not covered by the adverse-event analyses cited here, and the 2020 review discussed CGRP as a pathophysiological target rather than as a therapeutic agent given to people (PMID 32003253). Where no structured adverse-event data exist for a question, that absence is stated plainly rather than filled with inference.

How guidelines and position papers framed tolerability

The American Headache Society position statement update argued that CGRP-targeting therapies be considered a first-line option for migraine prevention, and it set out the evidence and considerations behind that position (PMID 38466028). The French Headache Society position paper on migraine treatment described how the available preventive and acute options, including CGRP-targeting drugs, were placed in clinical practice (PMID 39406556). A 2023 Japanese-language review of migraine medication and a 2017 German-language review of migraine therapy covered the same drug families within their national treatment landscapes (PMID 37194515; PMID 28497257). These documents are positions and reviews, not new adverse-event datasets, and the study-level tolerability comparisons they drew on were the pooled analyses described above (PMID 37208596).

Limitations of the reported adverse-event record

• Trial populations were selected. Prevention trials recruited adults meeting migraine criteria, and researchers in the 2025 Neurology review highlighted vascular risk and stroke as populations needing separate examination (PMID 40537071).
• Pooling hides drug-level differences. The 2023 network meta-analysis compared agents against each other rather than treating the class as uniform (PMID 36786548).
• Narrative reviews repeat the same trials. The 2024 handbook chapter and the 2025 Lancet review both summarised the existing prevention trial base for antibodies and gepants (PMID 38307640; PMID 40121062).
• Post-marketing reports differ from trial data. Signals discussed after approval were described in review form rather than as controlled comparisons (PMID 40121062).
• Comparisons with older preventives depend on indirect evidence. The comparative-effectiveness network meta-analysis relied on indirect comparison methods across drug classes (PMID 37208596).

What the body of work indicates

Taken together, the pooled safety analysis in Cephalalgia and the comparative-effectiveness analysis in The Journal of Headache and Pain examined tolerability and adverse events for CGRP-pathway antibodies and gepants in migraine prevention trials, while narrative and position sources placed those findings in clinical context (PMID 36786548; PMID 37208596; PMID 38466028). Gastrointestinal effects, injection-site reactions and non-specific general symptoms were the categories named most often, with hepatic history, blood-pressure reports and vascular populations handled as separate discussions in reviews (PMID 29691490; PMID 40121062; PMID 40537071). None of this constitutes a safety verdict for any individual, and nothing here should be read as guidance; clinical decisions belong with a licensed physician.

References

• Safety and tolerability of monoclonal antibodies targeting the CGRP pathway and gepants in migraine prevention: A systematic review and network meta-analysis (Cephalalgia, 2023)
• The comparative effectiveness of migraine preventive drugs: a systematic review and network meta-analysis (The Journal of Headache and Pain, 2023)
• Calcitonin gene-related peptide-targeting therapies are a first-line option for the prevention of migraine: An American Headache Society position statement update (Headache, 2024)
• CGRP monoclonal antibodies and CGRP receptor antagonists (Gepants) in migraine prevention (Handbook of Clinical Neurology, 2024)
• Calcitonin gene-related peptide-targeted therapy in migraine: current role and future perspectives (Lancet, 2025)
• CGRP-Targeted Migraine Therapies in Patients With Vascular Risk Factors or Stroke: A Review (Neurology, 2025)
• CGRP as the target of new migraine therapies - successful translation from bench to clinic (Nature Reviews Neurology, 2018)
• Calcitonin gene-related peptide (CGRP): role in migraine pathophysiology and therapeutic targeting (Expert Opinion on Therapeutic Targets, 2020)
• Headache: Treatment update (eNeurologicalSci, 2022)
• Migraine treatment: Position paper of the French Headache Society (Revue Neurologique, 2024)
• [Migraine Medication] (Brain and Nerve, 2023)
• [Therapy of migranes] (Der Nervenarzt, 2017)