Clascoterone for Hair Loss: How It Works, Studies and 2026 Status

Across forums, Reddit and YouTube, one name keeps coming up whenever new hope against genetically driven hair loss is discussed: clascoterone. This guide takes a sober look at the compound, what the studies actually show, where the limits lie and whether you can get hold of it yet.

What is clascoterone?

Clascoterone is a topical anti-androgen, chemically known as cortexolone 17α-propionate (INN: cortexolone 17alpha-propionate, development name CB-03-01, CAS 19608-29-8). It is applied directly to the scalp and targets the hormonal trigger of androgenetic alopecia, the most common form of hair loss in men.

Structurally it is a synthetic pregnane steroid derived from progesterone and 11-deoxycortisol. So it is a steroid, but not a corticosteroid: it acts as an anti-androgen, not as a cortisone preparation. The compound was developed by Cassiopea S.p.A. (Italy), now under the umbrella of Cosmo Pharmaceuticals.

The crucial point: clascoterone competitively blocks the androgen receptor in the dermal papilla cells of the follicle. There it competes with dihydrotestosterone (DHT) for the binding site. This slows the DHT-driven miniaturisation of the follicles without altering hormone production elsewhere in the body.

Winlevi, Breezula and clascoterone: the difference

Winlevi, Breezula and clascoterone all refer to the same active substance in different forms: clascoterone is the pure compound (INN), Winlevi the approved acne cream and Breezula the experimental hair loss solution. They differ in concentration, vehicle and indication, and that is exactly what matters therapeutically.

Winlevi contains 1% clascoterone in a cream for facial acne. Breezula is a 5% solution formulated to penetrate the scalp. According to the EMA product page, Winlevi was approved in the EU on 17 October 2025, whereas Breezula has no approval for hair loss (as of June 2026).

How does clascoterone work against hair loss?

The way clascoterone works is based on antagonism at the androgen receptor: the compound binds competitively to the receptor in the dermal papilla cells and prevents DHT and testosterone from switching on the genes that drive follicle shrinkage in androgenetic alopecia. So it acts as a local hormone blocker at the follicle itself.

In vitro, clascoterone inhibits androgen-driven transcription about as effectively as finasteride and, in DHT-stimulated scalp papilla cells, reduced IL-6 synthesis more strongly than the anti-androgen enzalutamide (Rosette et al. 2019, Journal of Drugs in Dermatology). It therefore acts directly on the biological trigger of miniaturisation.

The effect remains largely local. In skin and plasma, clascoterone is rapidly broken down by esterases into the inactive metabolite cortexolone. According to Mazzetti et al. (2019), the mean Cmax after 14 days of continuous use was 4.4 to 4.6 ng/ml; this active breakdown pathway markedly limits any systemic anti-androgen effect.

The mechanism explains the difference from the established treatments: finasteride inhibits the enzyme 5α-reductase systemically and thereby lowers DHT levels throughout the body. Clascoterone blocks only the receptor at the follicle, while DHT levels in the blood stay unchanged. Minoxidil, by contrast, does not interfere with the hormone system at all but instead extends the growth phase and promotes blood flow.

What do the studies on clascoterone show?

The studies on clascoterone show statistically significant effects against androgenetic alopecia, but they come mostly from company press releases rather than peer-reviewed full publications (as of June 2026). The key endpoint is TAHC (Target Area Hair Count): the number of non-vellus hairs per square centimetre in the treated area.

Phase II in men: absolute hair counts

The Phase II study on clascoterone (more than 400 men, 18 to 55 years, mild to moderate AGA, study centres in Germany, 12 months) compared several concentrations against the vehicle. According to the Cassiopea press release (April 2019), all active arms were significantly superior, with the numerically strongest being 7.5% twice daily at +14.3 hairs/cm².

Phase III in men (SCALP 1 and SCALP 2)

In the Phase III study on clascoterone (Breezula 5% solution), 1,465 men were randomised across two trials (SCALP 1 and SCALP 2, 51 centres in the USA and Europe). According to Cosmo’s topline data (December 2025), SCALP 1 achieved a relative TAHC improvement of +539% over placebo and SCALP 2 +168% (p < 0.05 in each case).

The 12-month data (April 2026) show, according to Cosmo, that men on continuous treatment achieved a 239% higher TAHC increase than those who switched to the vehicle after 6 months. CEO Giovanni Di Napoli stressed himself that these figures cannot be compared directly with the 6-month numbers. The safety profile remained at vehicle level.

Does clascoterone work in women too?

Whether clascoterone works in women is an open question: the early signals are insufficiently supported. In a Phase II study of 293 women, there was no significant advantage over the vehicle in the overall population. Only in the subgroup of women under 30 using 5% clascoterone was the TAHC difference significant (p = 0.0391, Cassiopea September 2021).

However, this subgroup was not designed to be statistically powered, and the sample size is not enough to support a general recommendation. A dedicated Phase III programme for women has not been announced so far (as of June 2026). For women, the compound is therefore considered experimental and unproven. More on this in the article on hair loss in women.

What are the side effects of clascoterone?

The side effects of clascoterone are mostly local: redness, flaking and itching at the application site, at vehicle level in the acne approval studies. Systemically, the compound has so far appeared largely unremarkable. Long-term data for continuous scalp use in AGA are, however, still lacking (as of June 2026).

One open question is the HPA axis (the hypothalamic-pituitary-adrenal system). In the Winlevi data, transient HPA suppression occurred in 5% of adults and 9% of adolescents after 14 days (Mazzetti et al. 2019); all cases normalised within 4 weeks of stopping. For months to years of scalp use of the 5% solution, sufficient long-term data are lacking.

The Winlevi label also reported a shift towards raised potassium levels in 5% of those treated (compared with 4% on the vehicle), the clinical relevance of which is unclear. According to the label, the compound is contraindicated in pregnancy and breastfeeding, in children under 12 and in people aged 65 and over. Clascoterone therefore cannot be described as free of side effects.

Clascoterone vs. finasteride vs. minoxidil

Clascoterone, finasteride and minoxidil act at different points: clascoterone blocks the androgen receptor locally, finasteride lowers DHT levels systemically and minoxidil promotes growth without any hormonal intervention. A direct head-to-head efficacy comparison of the three within a single study is so far lacking.

On post-finasteride syndrome (sexual dysfunction, mood and cognitive complaints persisting even after stopping): it is not clearly recognised in science as a distinct syndrome, but it is reported by a relevant number of affected people. The theoretical strength of clascoterone lies in not lowering blood DHT levels in the first place.

Combining clascoterone with minoxidil is discussed as theoretically sensible because of their different mechanisms of action, but clinical combination studies are so far lacking. Anyone already using minoxidil will find the basics in the article on minoxidil for hair loss.

Can you buy clascoterone or Breezula in the UK?

Breezula, the 5% clascoterone solution for hair loss, cannot be bought or prescribed in the UK (as of June 2026). According to Cosmo, the FDA marketing application is planned for early 2027; the earliest possible US approval would be mid to late 2027, with EU approval following behind.

The acne cream Winlevi (1%) has been available in the EU since October 2025, but only for acne, not for hair loss. Off-label use on the scalp is simply unsuitable: at 1% the concentration is too low (around 5 to 7.5% is needed for AGA) and the cream vehicle is formulated for facial acne; it clogs the hair and does not penetrate the scalp follicles adequately.

There are no official figures on cost. US market analysts estimate 90 to 150 USD per month, with no reimbursement. In the UK, androgenetic alopecia is not regarded as a condition that warrants funded treatment, so the NHS does not generally cover such treatment costs, and on private prescription it would be paid for out of pocket.

Who is clascoterone suitable for, and who not?

According to the study data, clascoterone is a candidate for men with mild to moderate androgenetic alopecia, that is, Norwood stages III (vertex) to V. It can stabilise follicles that are still present but cannot bring back follicles that have already died. Like all AGA treatments, it requires ongoing therapy; once you stop, the effect is lost.

In practice this means: Breezula, if approved, would be a solution applied twice daily to the dry scalp in the affected area, much like the way minoxidil is used. It is not a course of treatment but ongoing therapy over many years. In the 12-month data, men who switched to the vehicle after 6 months lost the gains they had previously achieved (Cosmo, April 2026).

The compound is not suitable in advanced AGA (Norwood VI to VII), where no living follicles remain, nor in pregnant or breastfeeding women or in children. A different distinction is crucial: diffuse hair loss does not respond to anti-androgens.

First identify the cause: AGA or diffuse hair loss?

Anti-androgens such as clascoterone target only the hormonal-genetic cause of androgenetic alopecia. Diffuse hair loss (telogen effluvium) has other triggers, such as iron deficiency (ferritin often below 30 to 70 µg/l), thyroid disorders, stress or poor nutrition. Here an anti-androgen is of no use; the cause has to be clarified first.

Before any drug therapy, therefore, comes a medical diagnosis with trichoscopy and, where appropriate, blood tests. Whether it is AGA or another form can be assessed through a visual pattern analysis of the scalp and the hair loss pattern. Such a hair analysis is, however, no substitute for a medical blood test, for example to check iron or thyroid values; more on this in the article on blood tests for hair loss.

Only once the cause is established can a treatment be sensibly decided on. This is exactly where the practical question arises for many people: clascoterone is not yet available, so what should you do until Breezula perhaps arrives?

Waiting for Breezula: what can affected people do until 2028?

Until Breezula is realistically available in the UK in 2028 or later, affected people do not have to wait idly. On the contrary: with hereditary hair loss, acting early counts, because follicles that have once died cannot be brought back by any medication. There are established, approved options for stabilising the hair you still have right now.

For immediate stabilisation, three approaches are well supported today: minoxidil (over the counter, topical, extends the growth phase), finasteride (prescription only, lowers DHT levels) and, as an addition, PRP treatment using your own blood. Which option is medically appropriate depends on the stage, tolerability and personal preference and belongs in medical hands.

If individual areas are already bald, on the other hand, because follicles there are permanently lost, no topical treatment can regenerate them. In that case, a hair transplant (FUE or DHI) is the medically established route, because it relocates the patient’s own DHT-resistant follicles from the back of the head into the thinning zones. A compound such as clascoterone could, in future, additionally help stabilise the remaining native hair.

The sensible first step, then, is to have your own type and stage of hair loss assessed. A free hair analysis from Elithair is a visual pattern analysis of your photos; with no obligation, it shows whether a hereditary pattern is present and which routes are realistic. It is not a substitute for a medical blood test, but it is a good starting point for further planning.

Development and approval timeline

The development of clascoterone spans from the acne approval to the completed hair loss studies. Should Breezula be approved, it would, according to Cosmo, be the first topical AGA medication with a new mechanism of action since minoxidil (1988) and finasteride (1997), that is, after more than 30 years.

Conclusion: clascoterone, state of research 2026

As Breezula, clascoterone is so far the only topical androgen receptor antagonist to have shown statistically significant results against androgenetic alopecia in a large-scale Phase III study. That is genuine progress, because no topical AGA medication with a new mechanism of action has come along in more than 30 years.

At the same time, a sober view is in order: the Phase III primary data have not yet been published in peer-reviewed form, and long-term safety over years and the final absolute hair counts are still outstanding. Approval in the UK calls for patience, realistically 2028 or later. Off-label use, home-mixing and buying from uncontrolled online sources are all clearly to be advised against.

Anyone suffering from visible hair loss today should first have the cause clarified by a doctor. For genetically driven hair loss with permanently lost follicles, a hair transplant remains the established, plannable option, while compounds such as clascoterone could in future additionally help stabilise the hair that is still present.

Frequently asked questions about clascoterone

Sources

Medically reviewed, as of June 2026. This guide is for information only and is not a substitute for medical advice, diagnosis or treatment. Clascoterone (Breezula) is not approved for hair loss. Do not make any treatment decision without consulting a medical professional.