Anti-CGRP Migraine Drugs Linked to Hair Loss in FDA Adverse Event Database | Research

The takeaway

CGRP inhibitors for migraine showed a 4-fold higher rate of hair loss reports compared to all other drugs in the FDA's adverse event system, with CGRP-targeting antibodies driving most of the signal.

PRR 4.06 for alopecia
CGRP inhibitors as a class showed 4-fold disproportionate alopecia reporting in the FDA database, with fremanezumab highest at 5.42x and a 12.5x signal vs triptans

What the researchers found

Analysis of FDA FAERS data through Q4 2021 revealed:

• 1,827 alopecia cases among 55,994 adverse events reported for CGRP inhibitors (3.26%)

• Class-wide proportional reporting ratio (PRR): 4.06 (95% CI: 3.88-4.25)

• By individual drug: fremanezumab PRR 5.42, erenumab PRR 4.29, galcanezumab PRR 4.11, eptinezumab PRR 2.06

• vs triptans: PRR 12.46 (far more alopecia reports with CGRP inhibitors)

• vs celecoxib: PRR 3.50

• vs anticonvulsants, onabotulinumtoxinA, or beta-blockers: no significant disproportionate signal

• Within the CGRP class: biologic antibodies had PRR 6.11 vs small-molecule CGRP drugs, indicating biologics primarily drive the alopecia signal

Why it matters

CGRP plays a role in hair follicle biology and growth cycles, so blocking it could biologically plausibly cause hair loss. With millions of patients now using CGRP inhibitors for migraine prevention, hair loss — even if uncommon — affects a significant absolute number of people. This study provides the first systematic pharmacovigilance evidence supporting the CGRP-alopecia connection and can inform prescriber counseling.

How the study worked

Retrospective disproportionality analysis of the FDA Adverse Event Reporting System (FAERS) database through Q4 2021. Thirteen MedDRA preferred terms defined alopecia cases. Proportional reporting ratios (PRR) with 95% confidence intervals were calculated comparing CGRP inhibitors against all other drugs and specific migraine comparators. A PRR >2.0 with lower 95% CI >1.0 and ≥3 cases defined a positive signal.

What this study cannot tell us

FAERS is a spontaneous reporting system subject to reporting bias, stimulated reporting (media attention on hair loss), and under-reporting. PRR signals indicate disproportionate reporting, not causation. Underlying migraine itself or comorbidities may contribute to hair loss. The analysis cannot determine incidence rates. The comparison drugs have different indications and patient populations, complicating direct comparison. Dose and duration information in FAERS is often incomplete.

How to read the evidence

This is a pharmacovigilance disproportionality analysis of the FDA's FAERS database. While it provides a strong safety signal across multiple CGRP drugs, FAERS data cannot establish causation, determine incidence rates, or control for confounders. It represents a hypothesis-strengthening analysis that warrants prospective investigation.

When this study was published

Published in 2022 with FAERS data through Q4 2021. As CGRP inhibitor use has continued to expand, additional real-world data on alopecia incidence are likely accumulating.

The bigger picture

CGRP is not just a pain molecule — it has roles throughout the body including in blood vessel dilation, wound healing, and hair follicle biology. As anti-CGRP drugs become long-term medications for chronic migraine, understanding their effects on non-pain tissues becomes essential. The finding that antibody-based CGRP drugs (which provide sustained blockade) show stronger alopecia signals than short-acting small molecules suggests that the duration and completeness of CGRP suppression matters for hair health.

Questions still open

Does the hair loss resolve after stopping CGRP inhibitors, and how long does recovery take?
Is the alopecia related to CGRP's role in hair follicle cycling, or to an indirect immune mechanism?
Do oral CGRP receptor antagonists (gepants) have a lower hair loss risk than antibody-based CGRP inhibitors due to less sustained blockade?

Common questions

Can CGRP migraine drugs cause hair loss?

This study found a strong signal in the FDA's adverse event database: CGRP inhibitors were associated with 4 times more hair loss reports than expected compared to all other drugs. Hair loss was reported with all four CGRP antibodies (erenumab, fremanezumab, galcanezumab, eptinezumab), with fremanezumab showing the strongest signal. While this doesn't prove causation, it suggests hair loss is a real side effect that patients should be aware of.

Why might blocking CGRP affect hair?

CGRP is a neuropeptide that isn't just involved in pain — it also plays roles in blood vessel dilation and tissue growth, including in hair follicles. CGRP receptors are present in hair follicle cells, and the peptide appears to influence hair growth cycles. When CGRP is blocked by migraine drugs, this may disrupt normal hair follicle function. The fact that long-acting antibody drugs showed stronger hair loss signals than short-acting drugs supports the idea that sustained CGRP blockade is the issue.

Read the original research

Alopecia signals associated with calcitonin gene-related peptide inhibitors in the treatment or prophylaxis of migraine: A pharmacovigilance study.

Pharmacotherapy, 42(10), 758-767

View on PubMed ↗Publisher’s paper ↗

Citation

Woods, Richard H. (2022). Alopecia signals associated with calcitonin gene-related peptide inhibitors in the treatment or prophylaxis of migraine: A pharmacovigilance study.. Pharmacotherapy, 42(10), 758-767. https://doi.org/10.1002/phar.2725