Peer-reviewed studies on hair loss, scalp science, and new treatments, explained in plain language by a trichology educator. No hype. No supplement ads. Just the science.
LPP is a lymphocytic primary scarring alopecia driven by a Th1/IFN-γ attack on the follicular bulge and the downregulation of PPAR-γ in the upper follicle. The Chiang 2010 JAAD paper introduced the Lichen Planopilaris Activity Index, the de facto outcome measure across the literature, and showed hydroxychloroquine 200 mg twice daily produces significant improvement in 69% of patients at 6 months and 83% at 12 months. The Karnik PPAR-γ mechanism paper. The Cho mycophenolate evidence at 83% response in HCQ-refractory disease. Low-dose naltrexone, oral retinoids, and the emerging JAK-inhibitor case series. What trichologists need to know about catching LPP before the follicles are permanently lost.
Read the breakdown →FFA was an Australian curiosity when Steven Kossard described it in 1994. Three decades later, a 2019 multicenter survey across nineteen countries identified it as the single most common primary scarring alopecia in specialist hair clinics. The 2019 GWAS in Nature Communications confirmed inherited susceptibility at HLA-B*07:02 and a putative causal missense variant in CYP1B1, embedding FFA firmly in the autoimmune-with-genetic-background framework. The sunscreen hypothesis remains contested, with case-control associations on one side and a 2022 study suggesting reverse causation through actinic damage on the other. The 2024 randomized trial of finasteride versus hydroxychloroquine put both agents on equal footing. The mechanism, the diagnostic signs that hide before the hairline visibly recedes, and the trichologist’s highest-impact role in catching FFA early.
Read the breakdown →Alopecia showed up as an adverse event in the STEP 1 and SURMOUNT-1 trials at 3.0% on semaglutide 2.4 mg and 5.7% on tirzepatide 15 mg, versus 1.0–1.5% on placebo. A 2024 FAERS pharmacovigilance analysis confirmed the signal is real and disproportionate in post-marketing data. The mechanism is primarily telogen effluvium from rapid caloric deficit and nutritional shifts, with a possible direct pharmacologic contribution still under investigation. The clinical protocol for the growing share of trichology clients on Ozempic, Wegovy, Mounjaro, and Zepbound — including the subset of women in whom GLP-1-driven shedding unmasks underlying pattern hair loss.
Read the breakdown →CCCA is the most common primary scarring alopecia in Black women and one of the most misdiagnosed conditions in hair loss practice. The 2019 NEJM paper identified loss-of-function PADI3 variants in 24% of biopsied cases, reframing what had long been blamed on relaxers and hot combs as a genetically influenced disorder. Johns Hopkins transcriptomic research mapped the fibroproliferative signature shared with scleroderma and keloid scarring, opening the door to anti-fibrotic therapy. A 2023 JAMA Dermatology case series on compounded topical metformin 10% is the first clinical translation of that mechanism. The genetics, the trichoscopy, the biopsy, the treatment ladder, and the narrow window before follicles are permanently lost.
Read the breakdown →It is the single most common cause of diffuse hair shedding in dermatology practice, and the COVID-19 pandemic tripled its incidence globally. A 2025 JAAD Reviews paper maps the full HPA axis and cytokine cascade — IL-6, TNF-α, substance P, and local follicular cortisol — that drives stress-mediated anagen termination. A 2024 biochemical study of 180 women found no significant differences in ferritin, vitamin D, biotin, zinc, or thyroid function between chronic TE patients and controls, challenging routine micronutrient assumptions. A systematic review of 1,628 cases questions whether “chronic TE” is even a distinct diagnosis. The mechanism, the pandemic data, the trichoscopy markers, and what practitioners need to know.
Read the breakdown →Spironolactone has been prescribed off-label for female pattern hair loss for more than three decades. A 2025 placebo-controlled pilot RCT showed that adding spironolactone 100 mg to topical minoxidil produced greater gains in terminal hair count, shaft diameter, and clinical improvement than minoxidil alone — with a 37.5% rate of menstrual irregularity. A 2024–2025 head-to-head trial in 204 women showed bicalutamide outperforming spironolactone on trichoscopic endpoints. A breakdown of the mechanism, the updated evidence, and what practitioners need to know about patient selection and combination therapy.
Read the breakdown →Dutasteride blocks both type I and type II 5-alpha reductase and suppresses 98% of serum DHT — compared to finasteride's 70%. A 2024 systematic review confirmed its superiority for hair regrowth. In 2025, a Phase II trial showed topical dutasteride producing +75.5 hairs/cm² with zero adverse events, a Phase III trial validated low-dose 0.2 mg oral dosing, a pilot RCT demonstrated thrice-weekly dosing as a viable alternative, and a meta-analysis found intralesional delivery effective especially combined with PRP. The evidence, the delivery routes, and what practitioners need to know.
Read the breakdown →Photobiomodulation is the only FDA-cleared device-based treatment for pattern hair loss — and in 2025, it received its first formal expert consensus in the Journal of the American Academy of Dermatology. A meta-analysis of 38 studies and 3,098 patients shows significant hair density increases over placebo with an effect size comparable to finasteride. New mechanistic data from Fudan University reveals how pulsed red light activates Wnt/β-catenin signaling and rescues dermal papilla cells from DHT damage. The evidence, the limitations, and what practitioners need to know about device selection and protocol.
Read the breakdown →Microneedling started as an anecdotal add-on — it is now one of the most-studied adjunctive hair loss treatments in dermatology. A 2024 meta-analysis of 13 RCTs and 696 patients, a 2025 meta-analysis of 12 RCTs showing earlier onset of regrowth, and a network meta-analysis ranking ten combination therapies. The Wnt/β-catenin mechanism, the gender-specific findings for female AGA, and why the protocol standardization gap matters as much as the efficacy data.
Read the breakdown →Minoxidil was never designed to grow hair — but oral dosing at 0.625–5 mg/day is now one of the most prescribed off-label hair loss treatments in dermatology. A 2025 meta-analysis of 27 studies and 2,933 patients, an international Delphi consensus on dosing from 43 specialists across 12 countries, head-to-head comparisons with topical formulations, and safety data from over 1,400 patients. The mechanism, the evidence, and what practitioners need to know.
Read the breakdown →Three oral JAK inhibitors — baricitinib, ritlecitinib, and deuruxolitinib — are now FDA-approved for severe alopecia areata, all targeting the IFN-γ/JAK-STAT positive feedback loop that collapses hair follicle immune privilege. Phase 3 trials in thousands of patients, 24-month long-term extension data, Bayesian network meta-analyses comparing efficacy, and the relapse reality when treatment stops. A breakdown of what trichologists need to understand.
Read the breakdown →Every follicle runs on a molecular timer — but what sets that timer? A 2025 Nature Communications study identified H2AK119ub as a chromatin-level switch that links FGF signaling to sustained HFSC quiescence, and shows that its loss drives the stem cell exhaustion behind age-related follicle decline. A 2024 Experimental Dermatology study challenged the standard 1–2% catagen figure with observed rates of 7.5%. And the circadian clock — BMAL1, Period1, CLOCK — turns out to be genuinely wired into the same timing machinery. A breakdown of the full molecular picture and what it means for clinical practice.
Read the breakdown →Pediatric hair loss accounts for 3% of all children's medical visits in the US — and the most common causes look nothing like adult alopecia. Tinea capitis can scar permanently if mismanaged. Alopecia areata in children now has the first FDA-approved treatment for patients aged 12 and older. Trichoscopy, including UV fluorescence dermoscopy, can distinguish the two at the chair. A breakdown of what practitioners need to know.
Read the breakdown →43 randomized controlled trials. 1,877 participants. A 2025 systematic review confirms PRP consistently improves hair density over placebo — and finds it comparable in efficacy to topical minoxidil for AGA. A breakdown of who responds, who doesn't, why preparation protocol may matter more than the treatment itself, and what the growth factor data actually shows.
Read the breakdown →DHT gets all the attention — but thyroid dysfunction, chronic cortisol elevation, estrogen decline, and PCOS each disrupt the hair cycle through completely different mechanisms. The Harvard Gas6 study, Mendelian randomization data on hypothyroidism and AA, the "follicle menopause" hypothesis, and what the 2023–2025 literature says about managing each pathway.
Read the breakdown →Traction alopecia is biphasic: early disease is reversible, late disease is not. The line between those two states is drawn by perifollicular fibrosis and stem cell niche destruction — and it is often crossed before anyone recognizes it. A breakdown of the mechanical biology, trichoscopic staging, and the clinical window that determines whether a follicle can still recover.
Read the breakdown →Exosome therapy is the fastest-growing conversation in regenerative hair medicine — and one of the most commercially overhyped. Eleven clinical studies show measurable improvements in hair density. The FDA has issued warning letters against multiple commercial products. A breakdown of the mechanism, the PRP comparison, and what the regulatory reality means for your practice.
Read the breakdown →Scarring alopecia doesn't just thin hair. It destroys the follicle permanently, and the sebaceous gland is often the first structure to go. A breakdown of the histopathology behind LPP, FFA, CCCA, and DLE, and why understanding where the damage starts changes everything about how you assess it.
Read the breakdown →Cold atmospheric plasma activates Wnt/β-catenin signaling in dermal papilla cells. A 2025 JAAD study documents hair growth in humans. But ozone therapy and CAP are not the same thing, and the evidence base is very different. Here's what the peer-reviewed literature actually says.
Read the breakdown →Melanocyte stem cells don't simply die when hair goes gray. A landmark 2023 Nature study revealed they get stuck in the follicle bulge, cut off from WNT signals that would activate them. New 2024 and 2025 research on luteolin, plant-derived melanogenesis stimulators, and exosome therapy is testing whether that process can be reversed.
Read the breakdown →It's not just "hair falls out, hair grows back." A meta-analysis of 2,179 patients reveals that more than 40% experience permanent partial alopecia. The mechanism behind stem cell damage, scalp cooling efficacy, and what post-chemo recovery actually looks like.
Read the breakdown →Alopecia areata patients show distinct gut microbiome profiles, depleted SCFA-producing bacteria, enriched inflammatory taxa, and disrupted intestinal barrier integrity. Multiple 2025 studies map the mechanism from gut dysbiosis to hair follicle immune privilege collapse.
Read the breakdown →A 2025 cross-sectional study of 520 hair loss patients found 66% were infested with Demodex mites, with a direct correlation between mite density and hair loss severity. How these microscopic parasites destroy follicles from the inside, and what actually kills them.
Read the breakdown →A 2025 clinical study of 100 women found that 65% with telogen effluvium had low ferritin, even when their labs came back "normal." The gap between lab reference ranges and hair-optimal ferritin is where most practitioners miss the diagnosis.
Read the breakdown →New research on AI-powered trichoscopy and non-invasive scalp detection is changing how we assess hair loss severity and predict treatment outcomes. Here's what the studies actually show, and why it matters for your practice.
Read the breakdown →The hair loss treatment landscape is changing faster than it has in 30 years. Clascoterone, GT20029, and PP405 represent three entirely different mechanisms of action, and they're all in clinical trials right now.
Read the breakdown →A 2025 multi-kingdom sequencing study proved that scalp microbiome dysbiosis is a measurable, predictable component of androgenetic alopecia. The disruption happens across the entire scalp, not just where you see thinning.
Read the breakdown →The Scalp Society offers AADP-accredited trichology courses, from foundational science to hands-on clinical mentorship. Built for professionals who want to understand the science underneath.
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