CGRP sex differences: what the research shows

What is CGRP and why does sex matter for how it works?

CGRP — calcitonin gene-related peptide — is a signaling molecule your nervous system releases, and sex-based differences in how the body produces and responds to it may help explain why migraine affects more women than men and why CGRP-targeting medicines don't work identically across sexes.

CGRP is a small protein (a peptide) made from the CALCA gene. Nerve endings release it, blood vessels respond by widening, and the brain's pain pathways use it as a messenger. When CGRP floods the system during a migraine attack, it contributes to the throbbing, the sensitivity to light, and the nausea many people describe. Medicines that block CGRP or its receptor — a docking site on cells — aim to interrupt that process.

Sex differences in CGRP expression are real, but the picture is genuinely complicated. A 2025 review of the published literature found that CGRP levels, receptor density, and downstream signaling vary between males and females across multiple tissues — and the direction of those differences is not always consistent from one study to the next (PMID 42699089). Estrogen and testosterone each appear to influence CGRP expression, which means the gap between sexes can shift across the menstrual cycle, perimenopause, and other hormonal transitions (PMID 42699089).

What the evidence does and doesn't say:

Women in studies of CGRP-related migraine show higher circulating CGRP levels during attacks than men in comparable studies, but researchers have not yet established whether that difference drives worse symptoms or simply reflects a different baseline (PMID 42699089).

Receptor expression — how many CGRP docking sites a tissue has — differs by sex in some organs but not others, and the pattern depends on which tissue researchers measured (PMID 42699089).

Most clinical trials of CGRP-targeting medicines enrolled more women than men, so efficacy data skew female, yet few trials were designed to test whether response rates differ by sex as a primary question (PMID 42699089).

Sex is biological — chromosomes, hormones, anatomy. Gender is social identity. Life stage matters separately: a 28-year-old and a 58-year-old may both be women, but their estrogen environments are entirely different, and CGRP biology shifts with those environments. None of this means any individual woman will respond to a CGRP medicine in a predictable way based on sex alone.

Researchers have not yet mapped how CGRP expression changes across every hormonal life stage, and the review authors describe the existing findings as "contradictory and nuanced" rather than settled (PMID 42699089). That uncertainty belongs in any honest conversation about these medicines.

This content is for general health education only and is not medical advice. Talk with a licensed clinician before starting, stopping, or changing any medicine.

What did the 2025 review find about CGRP expression across sexes?

A 2025 review found that CGRP sex differences in expression are real but inconsistent across tissues, species, and measurement methods — meaning no single, clean pattern holds across all studies. The evidence is genuinely mixed, and that mix matters for anyone trying to understand why migraine and pain conditions affect people differently depending on their biology.

CGRP — calcitonin gene-related peptide — is a small signaling protein released by nerve cells. It widens blood vessels and transmits pain signals, and it is the target of several approved migraine medicines.

The 2025 review examined studies comparing CGRP levels and receptor activity between males and females across multiple tissues. Key findings include:

• Women in some studies and female animals showed higher baseline CGRP levels in certain pain-processing tissues, but this pattern did not hold consistently across all tissue types or all study designs.
• The receptor that CGRP binds to — made of proteins called CLR and RAMP1 — showed sex-linked variation in some tissues, though the direction and size of that variation differed by body location.
• Estrogen appears to influence CGRP expression in some contexts, but the review stopped short of establishing a direct causal chain.
• Rodent studies and human studies did not always agree, which limits how confidently findings from animal models can be applied to people.

Studies used different tissues, different species, different life stages, and different ways of measuring CGRP. A plasma blood test and a tissue biopsy tell different stories about the same person. That fragmentation explains why the evidence stays contradictory.

CGRP-targeting medicines were tested in clinical trials that included women, but those trials were not always designed to detect sex-specific differences in response. The trial populations — not all women broadly — are the basis for what is currently known. The label reports what those specific trial populations showed; it does not settle every biological question the 2025 review raises.

The review did not cover pregnancy, perimenopause, or older age groups in depth, so evidence for those life stages is thin. Anyone making treatment decisions should discuss these open questions with a clinician who knows their full health picture.

This section is for general health education only and is not medical advice. It does not substitute for a conversation with a qualified healthcare provider.

How does estrogen interact with CGRP signaling?

Estrogen interacts with CGRP signaling in ways that help explain some of the sex differences researchers observe in CGRP expression and pain sensitivity across the lifespan. The relationship is real, but the science is still being mapped — and the picture is more complicated than a simple "estrogen turns CGRP up or down."

CGRP (calcitonin gene-related peptide) is a small protein your nervous system releases that widens blood vessels and carries pain signals. Estrogen, the hormone that fluctuates across the menstrual cycle, perimenopause, and menopause, appears to influence how much CGRP the body produces and how strongly cells respond to it. A 2025 review of CGRP sex differences found that estrogen can increase CGRP gene expression in certain nerve tissues — meaning higher estrogen levels may be linked to more CGRP activity in some contexts.

The findings are not uniform. Women in this study population showed higher CGRP levels in some tissues compared to men, but the direction and size of the difference varied by tissue type, age group, and hormonal status. The review described the evidence as "contradictory and nuanced" — which signals that broad generalizations about estrogen and CGRP do not hold across all situations.

The 2025 CGRP sex differences review identified a few specific patterns:

• Estrogen receptors appear on the same nerve cells that produce CGRP, giving estrogen a direct path to influence CGRP output.
• CGRP receptor expression differs by sex, meaning the same amount of CGRP may produce different effects in different people depending on receptor density.
• Hormonal shifts — such as those during the menstrual cycle or the transition to menopause — may change CGRP sensitivity over time, though the review notes this area needs more research before firm conclusions are possible.

A person's hormonal life stage may affect how CGRP-targeting medicines work, but the review stops short of saying estrogen levels predict treatment response. Clinical trials of CGRP-targeting therapies have not consistently enrolled enough participants across different hormonal life stages to answer that question directly.

Researchers know estrogen and CGRP interact. They do not yet know how to use that interaction to predict who will respond to a given therapy, at what life stage, or by how much.

This section is for general health education only and is not medical advice. Talk with a qualified clinician before making any decisions about your care.

Why are the findings on CGRP sex differences so contradictory?

The findings on CGRP sex differences are contradictory because studies measuring CGRP expression and receptor activity differ widely in methods, tissues sampled, and the sex and life stage of enrolled participants—and those design differences produce genuinely different biological signals, not just noise. This review of CGRP sex differences identifies inconsistency as a core problem in the literature, not a minor caveat.

What that means in plain terms: CGRP (calcitonin gene-related peptide) is a small protein the nervous system releases that widens blood vessels and carries pain signals. Its receptor—the docking site where CGRP attaches to trigger an effect—is not distributed the same way in every tissue or every person. When researchers measure CGRP in blood, they get a different picture than when they measure it in nerve tissue or in the fluid around joints. A study sampling blood plasma from premenopausal women will not automatically replicate findings from a study sampling trigeminal nerve tissue from postmenopausal women.

Three specific sources of contradiction stand out:

Hormonal variation across the menstrual cycle. Estrogen influences CGRP release, so a study that does not track or control for cycle phase measures a moving target. The CGRP sex differences review describes this as a recurring gap.

Age and reproductive life stage. CGRP levels and receptor sensitivity shift across puberty, reproductive years, and menopause. Pooling women in this study across those stages flattens real biological differences into apparent contradictions.

Animal models that do not translate cleanly. Many foundational CGRP studies used rodents, and sex-specific findings in rodents do not always replicate in human tissue—a gap the same review flags directly.

Sex assigned at birth, gender identity, hormonal status, and age are distinct variables. Studies that treat "female" as a single uniform category produce results that conflict with studies that separate those variables carefully.

The contradictions in this literature are real. They reflect genuine complexity in how CGRP works across different bodies and life stages. That complexity does not mean the science is useless—it means the findings need to be read with the study population clearly in view before drawing any conclusions about what they mean for any individual person.

This content is for general health education only and does not constitute medical advice. Speak with a qualified clinician about your own health situation.

What do CGRP sex differences mean for peptide-based pain treatments?

CGRP sex differences shape how peptide-based pain treatments work — and the evidence suggests those differences are real, though far from fully understood. A 2025 review found that CGRP (calcitonin gene-related peptide, a signaling molecule released by nerve cells that widens blood vessels and amplifies pain signals) and its receptor are expressed differently across sexes, with patterns that vary by tissue type, hormonal state, and life stage — meaning no single description covers everyone (PMID 42699089).

CGRP is a small protein the nervous system releases during migraine attacks. Peptide medicines called CGRP antagonists block either the molecule itself or its receptor to reduce migraine frequency and severity. Sex-based differences in how CGRP behaves matter because they may affect who responds to these treatments and how strongly.

What the review actually found:

Women in this study showed higher CGRP levels in certain tissues compared with male participants, but the direction and size of that difference shifted depending on the tissue examined and the hormonal context (PMID 42699089). Receptor expression — how many CGRP "docking sites" cells carry — also differed by sex, though the review describes the findings as contradictory across studies rather than settled (PMID 42699089). The review did not establish that these biological differences translate directly into different clinical outcomes from CGRP-targeting peptide medicines. That gap between mechanism and treatment response is where the evidence currently stops.

Migraine affects more women than men at most adult life stages, but biology is not destiny here. Age, reproductive status, and hormonal fluctuation all interact with CGRP signaling in ways that researchers are still mapping (PMID 42699089). The review does not address pregnancy or breastfeeding, and the label for individual CGRP-targeting medicines — not this review — governs what is known about use during those periods.

Sex-based differences in CGRP biology are documented. The clinical meaning of those differences for peptide treatment response is not yet established. A clinician familiar with your full history is the right person to weigh that evidence alongside your specific situation.

This section is for general health education only and is not medical advice. Speak with a qualified healthcare provider before starting, stopping, or changing any treatment.

What evidence gaps still need to be filled?

Researchers have identified real CGRP sex differences in how this peptide—calcitonin gene-related peptide, a signaling molecule involved in pain and blood vessel control—is expressed and how its receptor behaves, yet the evidence base still has significant gaps that limit what clinicians can confidently say to any individual woman. A 2025 review found contradictory and nuanced findings across studies, meaning the field has not yet produced a clear, consistent picture.

Several specific gaps stand out:

Sex-disaggregated study design. Most CGRP studies have been conducted in animal models or in mixed-sex human samples that did not analyze results separately by sex. The CGRP review notes that receptor expression patterns differ between sexes, but the mechanisms driving those differences remain poorly understood—too poorly to predict how a given person will respond to a CGRP-targeting medicine.

Pregnancy data scarcity. Trials of peptide medicines in pregnancy are rare. A 2025 systematic review protocol on insulin delivery in type 1 diabetes pregnancy was designed partly because existing data are so thin that researchers had to build new methods just to gather what little evidence exists. The same data scarcity applies to most other peptide classes.

Case reports as hypothesis, not proof. Single case reports, like the tirzepatide case in an adult female with Prader-Willi syndrome, can generate hypotheses. They cannot establish whether a treatment works across a population.

Life-stage stratification missing. Immune-related peptide research rarely stratifies by life stage. The rheumatoid arthritis study examined CD8+ T cell signatures specifically in women with early-stage disease—a useful step—but that kind of life-stage-specific design remains the exception, not the standard.

Antimicrobial peptides with anticancer potential. These face a separate set of unknowns. The 2025 review lists stability, delivery, and toxicity as unresolved challenges, and sex-disaggregated safety data do not yet exist for most candidates.

The evidence gaps are structural. Studies were not designed with sex, reproductive status, or life stage as primary variables, so the data needed to answer those questions simply do not exist yet. That is not a reason to avoid all peptide medicines—it is a reason to ask your prescriber what the trial population actually looked like, and to treat any claim of certainty with appropriate skepticism.

This content is for general information only and is not medical advice. Consult a qualified healthcare provider before making any decisions about your care.