Clascoterone (Breezula) for Hair Loss: What the Trials Have and Haven't Shown

Why this page exists

Searches for clascoterone have risen more than twentyfold in the past year, and most coverage repeats one number: 539%. We went to the developer's own releases, the trial registry records, the older phase 2 announcement and the prescribing label of the acne version to see what is actually known.

What it is

Clascoterone is an androgen receptor inhibitor applied to the skin. In pattern hair loss, the hormone DHT binds to androgen receptors in the dermal papilla cells at the base of the follicle; a 2019 laboratory study found clascoterone blocked androgen-driven signalling in human scalp dermal papilla cells. Read the study →

That makes it a different kind of drug from the options people already know:

• Finasteride and dutasteride reduce the amount of DHT the body makes.
• Minoxidil works through a separate, non-hormonal route.
• Clascoterone leaves DHT levels alone and tries to stop it acting on the follicle, locally.

The molecule is not new. It has been sold since 2020 as Winlevi, a 1% cream for acne. The hair-loss product is a different formulation: a 5% solution applied to the scalp twice a day. Read the Winlevi label →

What "539%" does and doesn't tell you

In December 2025, Cosmo Pharmaceuticals announced topline results from two identically designed phase 3 trials, SCALP 1 and SCALP 2, in 1,465 men. It reported a "5.39x" improvement in target-area hair count versus placebo in one trial and "1.68x" in the other. On the second co-primary measure — the men's own assessment of their hair — one trial reached statistical significance and the other showed only a positive trend. Read Cosmo's release →

What the release does not include: how many hairs either group actually gained, confidence intervals, or adverse-event numbers.

That matters because a relative figure depends as much on the placebo group as on the drug. As a purely illustrative example, if men on placebo gained 2 hairs in the measured area and men on the drug gained 10.8, the drug group did "5.4 times" better — even though the real-world difference is 8.8 hairs. The same drug in two trials with identical designs produced ratios of 5.39 and 1.68, which shows how much those ratios can move.

Cosmo has said it plans to publish the full phase 3 data in a peer-reviewed journal. Until it does, "539%" is a company-reported ratio, not a hair count.

The only absolute hair counts we could find

In July 2018, the drug's previous developer, Cassiopea, announced a six-month interim analysis of a phase 2 dose-finding trial: 404 men aged 18 to 55 at six sites in Germany, applying the solution twice a day, with hair counted in a 1 cm² target area. Among the 375 men in the interim analysis, the change in non-vellus (normal-thickness) hairs was:

Read Cassiopea's 2018 release →

Three cautions:

• This is a company press release of an interim analysis, not a peer-reviewed paper.
• The release compared the 7.5% result at six months with finasteride's twelve-month result from a different trial. Comparisons across separate trials, with different men and methods, are not reliable.
• The phase 3 trials used the 5% strength — which, in this interim, produced counts similar to 2.5% and lower than 7.5%. We have not found a public explanation of that choice.

An earlier, smaller phase 2 study in the US (2014–15, 95 men) compared a clascoterone solution with 5% minoxidil and placebo. Its registry record shows no posted results. Read the record →

What happens if you stop

The phase 3 trials had a second six-month stage. Men who had responded by month six were re-randomised to keep using clascoterone or switch to placebo. In April 2026, Cosmo reported that men who continued had a 2.39-fold greater improvement in hair count than men switched to placebo — and that men who switched experienced "a measurable and meaningful decline in hair count". Read Cosmo's release →

In other words, the company's own data suggest any gain depends on keeping going — something worth knowing before starting any long-term treatment.

Who was studied — and who wasn't

The registry records for both phase 3 trials show: SCALP 1 → · SCALP 2 →

• Men only, aged 18 and over, with mild-to-moderate pattern hair loss at the temples and crown (Norwood–Hamilton IIIv to V). There are no data for very early or advanced loss.
• Excluded: men with telogen effluvium or alopecia areata, a hair transplant, recent severe diet or weight change, bariatric surgery or recent nutritional deficiency, and anyone who had used topical minoxidil in the previous 12 weeks.
• Contraception: men who were sexually active with a female partner had to use contraception. The acne cream's label reports malformations in animal studies at high doses and no data in human pregnancy.

Women: Cassiopea announced a proof-of-concept trial in women in 2018. In our search of the trial registry in September 2026, we found no women's hair-loss trial of clascoterone with results. For now, there is no evidence either way for female pattern hair loss.

Safety: what's known and what isn't

What the company says about the hair solution: adverse events similar to placebo, "no significant systemic hormonal side effects" through twelve months, and "negligible systemic absorption". No numbers have been released.

What the acne cream's label says (1% cream, applied to the face):

• In a two-week maximum-use study, laboratory signs of adrenal (HPA axis) suppression appeared in 1 of 20 adults and 2 of 22 adolescents; all were normal four weeks after stopping.
• Potassium rose above normal in 5% of people on clascoterone and 4% on the inactive cream.
• Local irritation — redness, itching, scaling — was the most common side effect.
• In a two-year rat study, 1% and 5% cream caused thinning (atrophy) of the skin at the application site; it was not cancer-causing.

A 2024 report on the same maximum-use studies found 5 of 69 patients with abnormal adrenal test results, all back to normal about four weeks later and none with clinical symptoms. Read the report →

Why that isn't the whole answer: the hair product is a stronger solution, spread across much more skin, for years. A 2021 phase 1 heart-rhythm study — co-authored by an employee of the then-developer — noted that the solution formulation for hair loss "leads to a measurable systemic concentration and accumulation", unlike the cream. At deliberately high doses, it found no effect on the heart's QT interval. Read the study →

Until the phase 3 safety tables are published and reviewed by regulators, the hair solution's safety profile rests on the company's summary.

Can you get it now?

Not the product that was tested. The 5% hair solution is investigational. Cosmo's July 2026 half-year report says it plans to file in the United States in the first quarter of 2027 and in Europe in the second quarter of 2027. Read the report → A filing is the start of a regulatory review, not a decision.

The acne cream exists, but it is a 1% cream rather than the 5% solution the hair trials tested, and using it on the scalp is off-label. Be cautious of anything sold online as "Breezula" before regulators have reviewed it, and talk to a dermatologist before trying any anti-androgen.

Where laser caps fit, and where they don't

We sell a laser cap, so read this with that in mind.

Clascoterone and low-level laser therapy work in completely different ways, and both are aimed at androgenetic, or pattern, hair loss. No study has tested them together, and we are not going to suggest combining an investigational drug with anything.

The honest comparison for most people is with what exists today: finasteride and minoxidil have far larger and longer evidence bases than either clascoterone's released data or laser caps. If you are waiting for clascoterone, a conversation with a clinician about those options is a better use of the wait. Laser caps vs finasteride and minoxidil →

DHT and hair loss → · Pattern hair loss explained → · Why doctors are sceptical of laser caps →

Not intended to diagnose, treat, cure, or prevent any disease. The clinical studies referenced evaluated a clinically studied 650nm wavelength and the low-level laser therapy category broadly. Individual results vary and depend on consistent use over time. The FDA 510(k) clearance (K261253) is held by the manufacturer.