Clascoterone (Topical Scalp Formulation) — Safety, Research, Risks & Legal Status

Not medical advice. Clascoterone (Topical Scalp Formulation) is discussed here for informational and harm-reduction purposes only. We do not endorse use, and any dosing context is informational, not a protocol.

Also known as	CB-03-01; Cortexolone 17α-propionate; Breezula (investigational hair-loss formulation); WINLEVI (approved acne formulation)
Category	Research Chemical
CAS Number	19608-29-8
Approved indication (US)	Acne vulgaris ages 12+ (WINLEVI 1% cream, FDA NDA 213433, August 2020); hair-loss indication investigational only as of mid-2026
Hair-loss Phase 3 status	Both Scalp 1 and Scalp 2 trials completed December 2025; regulatory submission anticipated mid-2026; no approved hair-loss product as of mid-2026
Developer	Cosmo Pharmaceuticals (originator and sponsor of both acne and hair-loss programs)
Mechanism class	First-in-class topical androgen receptor antagonist; local tissue-level DHT blockade without systemic DHT suppression
Phase 3 hair-loss primary endpoint	Both trials met TAHC primary endpoint; 539% and 168% relative improvement vs. placebo (sponsor topline data; full peer-reviewed publication pending as of mid-2026)
US legal status	United States: Clascoterone 1% cream (WINLEVI) is FDA-approved (NDA 213433, August 2020) for acne vulgaris in patients 12 and older - a prescription drug, not a research chemical in that formulation. The 5% scalp solution (Breezula) for androgenetic alopecia is investigational: two Phase 3 trials completed December 2025, regulatory submission anticipated mid-2026, market availability not before approximately mid-2027 at earliest. Not a scheduled controlled substance. Topical scalp formulations are not available as approved products; any consumer access would be compounded or gray-market, outside a clinical trial setting.

What is Clascoterone (Topical Scalp Formulation)?

Clascoterone is a first-in-class topical androgen receptor (AR) antagonist. In its 5% solution formulation (Breezula), it is applied directly to the scalp to competitively inhibit dihydrotestosterone (DHT) binding at androgen receptors in dermal papilla cells, the target tissue implicated in androgenetic alopecia (pattern hair loss). Unlike systemic antiandrogens or 5α-reductase inhibitors such as finasteride, clascoterone acts locally at the receptor level with minimal systemic exposure. The 1% cream formulation is FDA-approved for acne; the scalp formulation remains investigational as of mid-2026.

How it works

Clascoterone competes with DHT for binding to androgen receptors in dermal papilla cells and sebocytes. Receptor occupancy inhibits AR-regulated transcription and suppresses DHT-stimulated IL-6 synthesis. The molecule's topical pharmacokinetics are designed to produce localized AR inhibition at skin target tissue with minimal systemic absorption, avoiding the plasma androgen suppression and associated side-effect profile of oral antiandrogens. In vitro studies in dermal papilla cells demonstrated AR antagonism superior to enzalutamide in that tissue-specific context. CAS: 19608-29-8.

Background & history

Clascoterone (CB-03-01) was developed by Cosmo Pharmaceuticals as a steroid derivative of cortexolone (11-deoxycortisol), designed to retain AR-binding affinity with a tissue-local rather than systemic mechanism. The acne program progressed through multiple Phase 1 and Phase 2 studies involving more than 1,700 patients pre-approval, followed by two pivotal Phase 3 RCTs that supported FDA approval of WINLEVI 1% cream in August 2020 - the first new acne mechanism approved in approximately 40 years. The EU granted approval in October 2025. The separate androgenetic alopecia program (Breezula 5% solution) completed two parallel Phase 3 trials (Scalp 1 and Scalp 2, combined n=1,465) with topline results announced December 2025. Regulatory submission for the hair-loss indication was anticipated mid-2026 with potential market launch estimated mid-2027.

What the research says

The scalp formulation is the most advanced topical AR antagonist for androgenetic alopecia in clinical development. Two identical Phase 3 RCTs (Scalp 1 and Scalp 2, combined enrollment approximately 1,465 participants) met primary endpoints measuring target-area hair count (TAHC), with relative improvement versus placebo reported at 539% and 168% in the two trials respectively. These figures represent relative change over baseline versus placebo, not absolute hair count gains. Twelve-month safety follow-up data were expected spring 2026. Mechanism data derive from in vitro dermal papilla cell studies. Phase 1 cardiac safety (QT interval) studies at supratherapeutic doses found no QTc prolongation. As of mid-2026, no published full peer-reviewed dataset from the Phase 3 hair-loss trials is available; all hair-loss efficacy data are topline announcements from the sponsor (Cosmo Pharmaceuticals).

Reported effects

Competes with DHT at androgen receptors in scalp dermal papilla cells, potentially reducing follicle miniaturization signal
In Phase 3 trials, statistically significant improvement in target-area hair count versus placebo at 12 months (full dataset not yet peer-reviewed as of mid-2026)
Local mechanism designed to avoid systemic antiandrogen effects - no plasma DHT suppression, no feminization, no sexual side effects at observed doses in the acne program
In the acne indication at 1%, demonstrated reduction in inflammatory and non-inflammatory lesion counts in two Phase 3 RCTs supporting FDA approval
Inhibits DHT-stimulated IL-6 synthesis in sebocytes and dermal papilla cells in vitro

Dosing & administration (informational)

In the FDA-approved acne indication (WINLEVI 1%), the approved concentration is 1% applied to affected facial areas twice daily per labeling. For the investigational androgenetic alopecia indication, Phase 3 trials used a 5% solution applied to the scalp at a frequency specified in trial protocols not publicly disclosed in detail. These are literature-reported concentrations from clinical programs for reference only. No dosing guidance for the hair-loss indication can be provided here, as no approved labeling exists and the compound is not available as an approved product for this use. Consult a licensed clinician or dermatologist for any therapeutic use.

This is general research/context information, not medical advice or a recommended protocol.

Safety & side effects

Most common adverse events in Phase 3 acne trials were local skin reactions: erythema, edema, scaling/dryness, and striae rubrae, generally trace to mild in severity
No serious adverse events attributed to clascoterone in Phase 3 acne trials; post-market experience over 4+ years in the US acne indication described as generally favorable
Mild asymptomatic reversible hypothalamic-pituitary-adrenal (HPA) axis suppression observed after 14-day maximum-use exposure in the acne program; resolved within 4 weeks of discontinuation
Small number of hyperkalemia cases reported post-market; FDA investigation found no association with measured plasma clascoterone levels
Phase 1 QT/QTc study at supratherapeutic doses found no clinically meaningful cardiac conduction effects
No antiandrogen systemic effects (gynecomastia, libido change, sexual dysfunction) observed in adolescent or adult populations in the acne program
Safety profile of the 5% scalp formulation in the hair-loss indication not yet fully published; 12-month follow-up data from Phase 3 hair-loss trials were pending as of mid-2026

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Who should avoid it

Use without a prescription or outside a supervised clinical context, as the scalp formulation is not an approved product as of mid-2026
Combination with systemic antiandrogens or other AR antagonists without medical supervision, as additive effects are unstudied
Application to abraded, irritated, or broken skin, which may increase systemic absorption beyond studied levels
Use in pregnancy or by those who may become pregnant - topical antiandrogens carry theoretical teratogenic risk; no adequate data exist for this formulation in pregnancy
Self-compounding or off-label use of non-pharmaceutical-grade material purchased outside a regulated supply chain

How it is commonly combined

No clinical stacking data exist for Breezula with other hair-loss agents (minoxidil, finasteride, dutasteride, low-level laser therapy) as of mid-2026. Combination regimens are discussed anecdotally, but no published trial has evaluated safety or efficacy of clascoterone plus any other agent in the hair-loss context. The mechanistic rationale for combining a topical AR antagonist with a 5α-reductase inhibitor (complementary pathway blockade) is sometimes discussed speculatively in the dermatology literature, but this is hypothesis-generating only. Stacking decisions should await published trial data and clinician guidance.

Legal & regulatory. United States: Clascoterone 1% cream (WINLEVI) is FDA-approved (NDA 213433, August 2020) for acne vulgaris in patients 12 and older - a prescription drug, not a research chemical in that formulation. The 5% scalp solution (Breezula) for androgenetic alopecia is investigational: two Phase 3 trials completed December 2025, regulatory submission anticipated mid-2026, market availability not before approximately mid-2027 at earliest. Not a scheduled controlled substance. Topical scalp formulations are not available as approved products; any consumer access would be compounded or gray-market, outside a clinical trial setting.

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Frequently asked questions

What is the difference between clascoterone (Breezula) and finasteride for hair loss?

Finasteride inhibits the 5α-reductase enzyme, reducing systemic DHT production throughout the body. Clascoterone blocks DHT at the androgen receptor locally in scalp tissue, without meaningfully lowering plasma DHT. The theoretical advantage is avoiding systemic antiandrogen effects (sexual side effects, feminization) associated with systemic DHT suppression. Whether this translates to a meaningfully different side-effect profile at population scale in the hair-loss program is not yet established from full published data.

Is Breezula (clascoterone 5% scalp solution) available to purchase?

No. As of mid-2026, Breezula has not been submitted for regulatory approval and is not an approved product in the US or EU. It is not commercially available. Access outside a clinical trial would require a compounded preparation, which is not equivalent to the studied formulation and carries regulatory and quality risks.

What were the Phase 3 hair-loss trial results?

Two Phase 3 RCTs (Scalp 1 and Scalp 2, combined approximately 1,465 participants) completed December 2025 and both met the primary endpoint of target-area hair count improvement versus placebo at 12 months. Sponsor-reported relative improvements versus placebo were 539% and 168% in the two trials. These are topline sponsor-announced data; the full peer-reviewed datasets had not been published as of mid-2026. Twelve-month safety follow-up was also pending.

What is the recommended dose for the hair-loss formulation?

There is no approved dosing regimen for this indication, and this reference does not provide dosing protocols. Phase 3 trials used a 5% concentration applied to the scalp. Consult a licensed dermatologist or physician for guidance on any therapeutic approach to androgenetic alopecia.

Are there systemic antiandrogen side effects from the scalp formulation?

In the acne program at 1%, no systemic antiandrogen effects (gynecomastia, sexual dysfunction, libido change) were observed in either adolescents or adults. The 5% scalp formulation involves a higher concentration; full safety data from the hair-loss Phase 3 program were not yet published as of mid-2026, and longer-term population-level safety will only emerge post-approval if regulatory submissions are successful.

Can clascoterone be used alongside other hair-loss treatments?

No clinical trial data evaluate clascoterone in combination with minoxidil, finasteride, dutasteride, or other agents in the hair-loss setting. The mechanistic complementarity with 5α-reductase inhibitors is discussed speculatively in some literature but is not established. Any combination use should involve a clinician and be grounded in published evidence as it becomes available.

References & further reading

PubMed: Clascoterone Phase 3 acne RCTs - PMID 32320027 (efficacy and safety topical clascoterone cream 1% facial acne two phase 3 randomized clinical trials)
PubMed: Clascoterone androgen receptor antagonist dermal papilla cells - PMID 30811143 (cortexolone 17 alpha propionate androgen receptor antagonist dermal papilla cells in vitro)
PubMed: Clascoterone QT interval Phase 1 cardiac safety - PMCID PMC8251570 (cortexolone 17 alpha propionate QT interval phase 1 study)
ClinicalTrials.gov: search 'clascoterone androgenetic alopecia' or 'Breezula' for Scalp 1 and Scalp 2 Phase 3 completed trials
PubMed: search 'clascoterone topical cream US experience post-approval dermatology 2024 2025' for 4-year post-market acne safety data