Why do cgrp cause hair loss

Content on WhatAnswers is provided "as is" for informational purposes. While we strive for accuracy, we make no guarantees. Content is AI-assisted and should not be used as professional advice.

Last updated: April 8, 2026

Quick Answer: CGRP (calcitonin gene-related peptide) does not directly cause hair loss; rather, CGRP-targeting migraine medications like erenumab, fremanezumab, and galcanezumab have been associated with hair loss as a rare side effect in clinical trials. For instance, in a 2021 study of erenumab, approximately 1-2% of patients reported hair loss, compared to 0.5-1% in placebo groups. This side effect is typically mild and reversible upon discontinuation, with cases often resolving within months. The link was first noted in post-marketing surveillance around 2018-2019 after FDA approvals of these drugs.

Key Facts

CGRP-targeting migraine drugs cause hair loss in 1-2% of patients in clinical trials
First reported cases emerged in post-marketing data around 2018-2019
Hair loss is typically reversible within 2-6 months after stopping medication
Mechanism may involve CGRP's role in hair follicle cycling and inflammation
FDA labels for drugs like Aimovig (erenumab) list alopecia as a potential side effect

Overview

CGRP (calcitonin gene-related peptide) is a neuropeptide involved in migraine pathophysiology, leading to the development of CGRP-targeting medications for migraine prevention. These drugs, including monoclonal antibodies like erenumab (Aimovig, approved by FDA in May 2018), fremanezumab (Ajovy, approved September 2018), and galcanezumab (Emgality, approved September 2018), work by blocking CGRP or its receptors. Hair loss emerged as an unexpected side effect during post-marketing surveillance, with initial case reports published in 2019-2020. Historically, CGRP was discovered in 1982 and has been studied for its roles in vasodilation and pain transmission, but its connection to hair biology gained attention only recently with these clinical observations. The incidence is low but significant enough for regulatory agencies to monitor it.

How It Works

CGRP may influence hair loss through its effects on hair follicle cycling and inflammation. In normal physiology, CGRP is expressed in sensory nerves around hair follicles and modulates hair growth phases, particularly the anagen (growth) and catagen (regression) stages. By inhibiting CGRP, these drugs might disrupt this balance, potentially shortening the anagen phase or prolonging the telogen (resting) phase, leading to increased shedding. Additionally, CGRP has anti-inflammatory properties, and its blockade could exacerbate inflammatory responses in the scalp, contributing to conditions like telogen effluvium. The exact mechanism isn't fully understood, but studies suggest it involves interactions with immune cells and growth factors in the hair follicle microenvironment. This process is dose-independent and varies among individuals, with most cases being mild and non-scarring.

Why It Matters

Understanding CGRP-related hair loss is crucial for patient care and drug safety. For migraine sufferers, these medications offer significant relief, with clinical trials showing up to 50% reduction in migraine days for many patients. However, hair loss can impact quality of life and adherence to treatment, making awareness among healthcare providers essential. It highlights the need for balanced risk-benefit assessments and patient monitoring. From a broader perspective, this side effect sheds light on CGRP's understudied roles in dermatology and hair biology, potentially informing future research on hair disorders. Regulatory bodies like the FDA continue to update drug labels to include this information, ensuring transparency and informed decision-making for patients worldwide.