From The Desk of Dr. Maida: Hair shedding on GLP-1s

A recent wave of studies reflects a shift in hair loss research that goes beyond simply identifying new treatments: One study explores how an old antihistamine might work when packaged in a more sophisticated delivery system; another explains why patients on semaglutide and tirzepatide are seeing increased shedding (temporarily); and others examine peptides that target multiple drivers of hair growth at once. A look into a few studies and what they might mean for people experiencing hair thinning.

Can An Allergy Medication Help Your Hair Grow?

The study: Targeted Transferosomal Delivery of Cetirizine: A New Approach to Alopecia Management

What the research is about

Researchers took cetirizine, the antihistamine you might take for allergies, and tested whether it could help with hair growth when delivered in a tiny, flexible bubble made from fats that delivers ingredients into the skin called a transferosome. The idea is that cetirizine might support hair growth by increasing prostaglandin E2 (which promotes follicle activity) while reducing prostaglandin D2 (which inhibits it).

The challenge with topical treatments is that they often don't penetrate well or wash off too quickly. So researchers created this transferosome formulation to help the cetirizine actually get where it needs to go and stay there longer. They tested it in mice with testosterone-induced hair loss, and the results were promising: the treated group showed thicker hair after 10–15 days, with increased expression of IGF-1 and VEGF; two key markers for follicle growth and blood vessel support.
But, this was only tested in mice, and while the transferosome version worked well, it wasn't always dramatically better than regular cetirizine gel. Plus, they didn't compare it directly to minoxidil, so we don't know how it stacks up against that very common and well-established treatment.

Why I'm excited

This study shows how delivery technology can make a huge difference. Cetirizine isn't new, but packaging it in a way that actually gets it into the scalp tissue efficiently is where innovation happens. It's a reminder that sometimes it's not just about finding new ingredients; it's about getting existing ones to work better.

The Real Reason Hair Shedding Can Happen On GLP-1s

The study: GLP-1 Therapies and Hair Loss: A Systematic Review of Current Evidence and Implications for Counseling

What the research is about

This systematic review looked at 24 studies and confirmed what many people using GLP-1 medications (like semaglutide and tirzepatide) for weight loss have been experiencing: increased hair shedding. The incidence seems to be around 5–7% in clinical trials, and it's more common at higher doses and in people losing weight rapidly.

The hair loss is mostly telogen effluvium (TE);  stress-related shedding where several follicles shift into the resting phase at once, and sometimes it unmasks underlying androgenetic alopecia (pattern hair loss).

Here's the good news: the negative impact of GLP-1s is likely an indirect effect of rapid weight loss, caloric restriction, and potential nutrient deficiencies. The review shows that once weight stabilizes and nutrition improves, hair loss typically resolves within a few months.

Why I'm excited

This reframes GLP-1–associated hair loss as a manageable, metabolic effect rather than direct follicle damage. And it’s preventable and manageable with the right approach: slower weight loss, adequate protein and nutrient intake, and possibly targeted supplementation. 

A Next Generation Peptide That Could Target Hair Loss From Many Angles

The study: A Novel Cell-Penetrating Peptide Supports Hair Follicle Growth Through Anti-Inflammatory and Growth Factor–Associated Mechanisms in Preclinical Models

What the research is about

Researchers tested whether a cell-penetrating peptide called DualPep-ALO could stimulate hair growth by working on multiple pathways at once, including increasing dermal papilla cell proliferation (those are the cells that regulate hair growth), activating important follicle signaling pathways like Wnt/β-catenin and ERK, restoring antioxidant activity, and reducing inflammatory markers like TNF-α and IL-6.

In human scalp follicles tested in the lab, DualPep-ALO promoted follicle elongation, kept follicles in the growth phase longer, increased cell proliferation, and boosted growth factors like VEGF, HGF, and EGF. The effects were dose-dependent and comparable to minoxidil.
This is still preclinical, as the peptide was tested in cells and isolated follicles, not on actual human scalps yet.

Why I'm excited

This peptide tackles multiple drivers of hair loss simultaneously. It stimulates growth signals, reduces inflammation, and fights oxidative stress. That multi-pronged approach is exactly what we need, because hair loss is rarely caused by just one factor. Cell-penetrating peptides like this represent a next-generation approach that could work alongside or even improve upon treatments like minoxidil.

Can Peptides Compete With Minoxidil?

Study: VENEZE Peptide Factor Hair Serum Compared With Topical 2% Minoxidil for Androgenetic Alopecia

What the research is about

This is an upcoming clinical trial that will directly compare a peptide-based hair serum to 2% minoxidil in 80 adults with androgenetic alopecia, the most common type of thinning in women and men. Participants will use either the peptide serum or minoxidil twice daily for 24 weeks, and researchers will measure hair density, hair diameter, terminal hair count, and patient-reported improvements.

The trial is randomized, triple-masked (so neither participants, investigators, nor evaluators know who's getting what), and designed to see if a peptide serum can actually perform as well as minoxidil; the established standard treatment. The trial is expected to run from April 2026 through November 2026 so we don’t have results yet.

Why I'm excited

This study is comparing peptides head-to-head with a well-established, proven treatment in people with pattern hair loss. If the results are positive, this could be a major validation for peptide-based topicals as a clinically-validated option for androgenetic alopecia.  

Frequently Asked Questions

Can allergy medicine really help with hair growth?

Possibly, but it’s too early to know for certain. Researchers are looking at cetirizine (an antihistamine) because it may shift certain scalp signals to support hair growth. In a recent study, it worked in mice, especially when delivered in a way that helps it penetrate the scalp more effectively. But we don’t yet have strong human data, and it hasn’t been compared directly to standard treatments like minoxidil.

Do GLP-1 medications directly cause hair loss?

Not directly. These medications don’t appear to damage hair follicles themselves. Instead, hair shedding is most likely related to the hormonal and nutrient shifts that come with rapid weight loss. These changes can trigger telogen effluvium, a common form of hair shedding.

Do peptides really help with hair growth and regrowth?

Yes, there is growing scientific evidence on peptides for hair growth showing they can support healthier, fuller-looking hair. Rather than acting as a quick fix, peptides for hair regrowth work by strengthening follicles, improving anchoring, and reducing shedding. Over time, this can lead to thicker, more resilient hair.