DOSEGUY

CB-03-01

weak data

Also seen as: Clascoterone, clascoterone, Breezula, Winlevi

The Dose Guy’s verdict
Sep 1, 2026
2 sources

CB-03-01 is the topical antiandrogen that actually went through clinical trials, earned FDA approval for acne, and is being studied for hair loss under the Breezula name. The pitch is compelling: block androgens right at the follicle without touching your hormones systemically. The catch is that every published human trial is for acne, not hair. Run finasteride and minoxidil first, the proven pair. CB-03-01 is an add-on experiment for people who want a local antiandrogen with real safety data behind it, not a replacement for things that work.

Would I take it?Caution, not proven for hair yet.

What it is

Also called clascoterone, CB-03-01 is a cortexolone derivative that blocks androgen receptors locally in the skin. Where finasteride stops DHT from being made, CB-03-01 stops it from acting at the receptor, and it does this topically so the drug stays where you put it. In cell studies it matched finasteride’s ability to shut down androgen-driven gene expression in human scalp cells, and the animal work showed strong local antiandrogenic activity with no systemic signal. That local-only profile is the whole point: the anti-androgen effect without the hormonal footprint.

This separates CB-03-01 from the research chemical antiandrogens like RU58841 and pyrilutamide. CB-03-01 has FDA approval for acne, published phase 3 safety data, and a known pharmacokinetic profile. It is a real drug, not a grey-market gamble, which matters when you are putting something on your scalp every day.

What the research shows

Real trials exist, but for acne, not hair:

In two phase 3 acne trials with 1,440 patients, CB-03-01 cream 1% beat vehicle at 12 weeks, with treatment success of 20.3% versus 6.5% in the stronger trial. Adverse events were mild and mostly local skin reactions.JAMA Dermatol 2020 · two phase 3 RCTs · n=1440
After 14 days of twice-daily CB-03-01 cream 1%, 3 of 42 patients had an abnormal stimulated cortisol response, but none showed clinical adrenal suppression and all three normalized within four weeks.JDD 2019 · phase 2a PK · n=42
No published human efficacy results for CB-03-01 in hair loss exist. The Breezula alopecia program has been discussed publicly but no trial abstract has appeared in PubMed.as of Aug 2026

Realistic protocols

Running CB-03-01 for hair right now means extrapolating from acne data and community experience. The mechanism makes sense, the safety profile from acne trials is clean, and people do apply it to their scalp. But no published trial has measured whether it actually regrows hair in humans.

If you run it, apply topically to the affected scalp twice daily, the frequency the acne trials used. The acne program tested a 1% cream, but the Breezula alopecia program studied higher concentrations, so the 1% you can get is what is available, not what the hair trials tested. It pairs logically with minoxidil since the mechanisms are completely different: one blocks the androgen signal at the follicle, the other stimulates growth through vasodilation. Consistency matters more than dose with topicals, so daily application is the floor.

Application1% topical, 2x dailyTo affected scalp areas. Twice daily matched the acne trial regimen.
The stack+ minoxidilDifferent mechanisms, logical pairing. Anti-androgen plus growth stimulation.
Patience6+ monthsTopical antiandrogens are slow. Give it time before judging.

Side effects

The acne trials mapped a clean safety profile, but scalp-specific data is still missing:

commonMild erythema at the application site, the most frequent reaction in acne trials.
monitorA small HPA-axis signal: 3 of 42 showed transient abnormal cortisol responses in the PK study, all self-resolving. No clinical adrenal suppression observed.
unknownNo published scalp-specific safety data. The acne profile is reassuring, but the scalp is different skin with different exposure patterns, and nobody has measured it in a published trial.
anecdotalScalp dryness and irritation reported by people running it off-label for hair. Consistent with what any topical cream does to skin used to just shampoo.

Where to buy

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