Hairloss AI / Blog / PP405 Hair Loss Treatment

What Is PP405 Hair Loss Treatment?

This guide is for men who have seen PP405 discussed online as a new way to reactivate dormant hair follicles. It explains how the experimental drug works, what its early Phase 2a trial results actually show, how it differs from finasteride and minoxidil, and when it might realistically become available.

Man applying a dropper of topical treatment to his hairline

If you've come across the PP405 hair loss treatment online, you've probably seen it described as a new way to regrow hair by reactivating dormant follicles. Some claims go even further, suggesting it could eventually replace finasteride or minoxidil, or even become a cure for baldness.

The online discourse is interesting, but you want to know how much of the hype is actually true. Does PP405 really regrow hair? Can it work in areas that already look bald? How safe does it appear so far? And how close is it to becoming something people can actually use?

This article explains how PP405 works, what the clinical trials have shown so far, what remains unproven, and whether it's worth waiting for.

What Is PP405 Hair Loss Treatment?

PP405 is an experimental topical drug being developed by Pelage Pharmaceuticals to treat androgenetic alopecia by reactivating inactive hair follicles. It isn't currently FDA-approved or available as a commercial hair-loss treatment.

Androgenetic alopecia is the medical term for female and male pattern hair loss.

PP405 is a small molecule, meaning a relatively small chemical compound designed to interact with a specific biological target.

It is also investigational, meaning researchers are still testing whether the drug is safe and effective enough to receive regulatory approval.

PP405 is applied directly to the scalp as a topical gel. Unlike finasteride, which slows or stops the progressive miniaturization of the follicles and prevents further pattern hair loss by reducing the amount of the dihydrotestosterone (DHT) hormone in the blood and scalp, PP405 is being developed to affect how hair follicle stem cells use energy.

As of August 25, 2026, its registered Phase 2a study involving 78 adults is listed as completed. A Phase 2a trial is an early clinical study that continues assessing safety while looking for the first meaningful signs that a treatment may work. Pelage says it plans to begin late-stage trials in 2026, but a PP405 Phase 3 study is not yet publicly registered on ClinicalTrials.gov.

How Does PP405 Work for Hair Loss?

PP405 is designed to change the energy metabolism of hair follicle stem cells so that dormant follicles may become active and start producing visible hair again. Specifically, it aims to produce terminal hair (the thick, fully pigmented hair that provides adequate scalp coverage) instead of the typical pattern of hair loss.

Hair follicle stem cells are regenerative cells inside the follicle that help initiate a new hair growth cycle. A dormant follicular unit is still physically present in the scalp, but it has currently stopped producing a visible terminal hair.

The idea that some apparently dormant, bald follicles may remain biologically recoverable didn't begin with PP405.

In a 2011 study comparing bald and haired scalp from men with androgenetic alopecia, researchers found that balding areas still contained the same number of original hair follicle stem cells as non-balding areas but had far fewer progenitor cells. Progenitor cells are the more active descendants of stem cells that help build a growing hair.

This finding helps explain the PP405 strategy: in at least some male pattern baldness follicles, the problem may not be the complete disappearance of stem cells but their failure to activate properly. It doesn't prove that every longstanding bald follicle can recover, though.

The biological rationale of PP405 also comes from a 2017 laboratory study on hair follicle stem-cell metabolism in mice. Scientists discovered that dormant hair stem cells use lactate as a biological "on switch" to trigger a new growth cycle. Normally, cells produce a compound called pyruvate and feed it directly into their powerhouses (the mitochondria) through a gateway called the mitochondrial pyruvate carrier (MPC).

However, when researchers blocked this gateway, the trapped pyruvate was forced to convert into lactate in the surrounding cell fluid instead. This sudden surge in lactate tricked the dormant stem cells into waking up and accelerating the hair-growth cycle.

PP405 is designed to exploit that metabolic switch by targeting the MPC. The important question, however, is whether that mechanism produces enough visible human hair growth to matter cosmetically.

What Did the PP405 Clinical Trial Results Show?

Early PP405 trials suggest the treatment is affecting hair follicles as intended and may increase hair density in some people. However, the evidence is still early, and most of the results showing how well it works have been reported by the company rather than published in a full peer-reviewed study.

What Did the Phase 1 Study Show?

The early PP405 research mainly aimed to determine whether the drug reached its intended biological target.

Pelage reported that PP405 increased Ki67 activity after seven days of 0.05% topical treatment. Ki67 is a marker researchers use to identify and measure cell division, and an increase only confirms that PP405 successfully pushed resting cells to divide actively.

The company also reported similar biological activity in ex vivo experiments, meaning living human scalp tissue studied outside the body, and said PP405 wasn't detected in the bloodstream during the early human study.

This is evidence of target engagement, meaning the drug appears to affect the biological process it was designed to influence.

It is an important step, but increased cell activity doesn't translate to cosmetically meaningful hair regrowth.

What Does the 31% PP405 Result Actually Mean?

The registered Phase 2a PP405 clinical trial enrolled 78 men and women with androgenetic alopecia. Participants applied 0.05% PP405 gel or placebo once daily for four weeks and were followed for 12 weeks.

Man applying a hair treatment product with a dropper

The main purpose was to assess safety and pharmacokinetics, which describe how much of a drug enters the body and what happens to it after administration. Hair-growth measurements were exploratory endpoints, meaning researchers looked for early signs that PP405 might improve hair growth instead of trying to prove its effectiveness at this stage.

At week eight, Pelage reported that 31% of treated men with advanced hair loss (typically corresponding to higher stages on the Norwood scale) achieved more than a 20% increase in hair density, compared with 0% in the placebo group.

To be clear, this doesn't mean every man in the trial regrew 20% more hair. It simply means that roughly one-third of the men in that advanced hair loss subgroup hit the milestone of gaining at least 20% more visible hair.

Still, the early results are promising: measurable growth appeared after four weeks, and new terminal hairs emerged from previously inactive follicles.

However, significant questions remain until larger trials are completed:

  • Consistency: How many men will reliably see these results in a larger population?
  • Cosmetic Impact: Is a 20% density increase enough to actually cover thin areas visually?
  • Longevity: Will the new hair stay once treatment ends, or does it require daily, lifetime use to keep the new hair from falling out?

PP405 vs Minoxidil and Finasteride: How Is It Different?

PP405 targets a different biological pathway than finasteride or minoxidil, so it shouldn't currently be viewed as a proven replacement for either treatment.

Finasteride reduces the conversion of testosterone into DHT, helping slow the hormonal process that drives follicle miniaturization in genetically susceptible men.

Minoxidil supports follicle activity and increases blood supply to the follicles to aid growth, but it doesn't directly block DHT.

PP405 is being developed to activate dormant hair follicle stem cells by changing their metabolism.

Does PP405 Block DHT?

No, PP405 doesn't block DHT, so its mechanism is fundamentally different from finasteride. However, being "non-hormonal" doesn't automatically make it safer. Male pattern baldness is driven by genetic sensitivity to the DHT hormone, which causes follicles to shrink over time.

Even if PP405 successfully reactivates dormant follicles, researchers still need to determine whether those newly awakened hairs can remain healthy while underlying DHT activity continues.

Could PP405 Be Used With Minoxidil or Finasteride?

Possibly, but there is not yet enough clinical evidence to say whether combining them improves results or remains safe long-term.

Since they target different pathways, a combination approach could work. But until clinical trials test PP405 alongside established treatments, it would be premature to recommend the combination or assume the effects will simply add together.

Can PP405 Regrow Hair on Bald Areas, and What Is Still Unknown?

PP405 may reactivate some follicles that have stopped producing visible hair, but there is no evidence it can restore every longstanding bald area or create entirely new follicles.

When Pelage describes growth from a "previously dormant" follicular unit, it means the follicular structure was already there but had not been producing visible terminal hair. It doesn't mean PP405 created a brand-new follicle.

That also means a completely smooth area that has been bald for many years shouldn't be assumed to contain recoverable follicles. Whether hair loss can be reversed depends heavily on how much follicle function remains.

There are also still many questions about PP405 that we don't have answers to. We don't yet know how many people will respond in larger populations or whether sex, age, hair-loss severity, duration, or hair type changes the likelihood of success.

We also don't know how durable PP405 hair regrowth will be. The public evidence doesn't establish whether treatment would need to continue indefinitely, whether follicles remain active after treatment ends, or what happens after stopping. This is particularly important because existing treatments such as minoxidil generally require continued use to maintain their benefits.

Safety also needs longer follow-up. Pelage reported no detectable systemic absorption in the Phase 2a trial, which is encouraging, but that doesn't prove zero systemic risk. Larger, longer studies can better detect uncommon reactions, cumulative effects, or problems that don't appear during a short early trial.

When Will PP405 Be Available?

No confirmed PP405 release date exists, and PP405 is not FDA-approved or legally available as a commercial hair-loss treatment. No confirmed retail price or approved dosing schedule exists.

Status verified August 25, 2026: ClinicalTrials.gov lists the Phase 2a study as completed. Pelage has publicly said it intends to begin late-stage studies during 2026, but no PP405 Phase 3 trial is currently listed in the U.S. registry.

Late-stage or Phase 3 trials are larger studies intended to confirm whether a drug provides a meaningful treatment benefit and to collect broader safety information. The FDA notes that Phase 3 studies commonly involve hundreds or thousands of participants, making them better suited to identifying less common side effects than early trials.

Successful trials would still need a regulatory submission and FDA review before PP405 could be approved for sale.

So anyone advertising genuine retail PP405 today should be treated cautiously. Pelage itself has stated that PP405 remains investigational and has not been FDA-approved for commercial sale. A so-called replica or research chemical has not been shown to match the formulation, concentration, purity, or delivery system used in the clinical studies.

Conclusion

PP405 is one of the more interesting experimental approaches to male pattern hair loss because it targets hair follicle stem-cell metabolism instead of DHT itself.

Early human results suggest biological activity and a measurable density response in a subset of men, but the evidence is still preliminary. We still don't know how consistently it works, whether gains last, or which bald areas remain recoverable.

For now, PP405 is worth following, but not treating as an approved cure or a reason to postpone actual proven care like finasteride and minoxidil.

References

Keep reading

  • Iron Deficiency Hair Loss

    This guide is for men who suspect low iron is behind their shedding. It explains how iron deficiency contributes to hair loss, what low-ferritin shedding actually looks like, how it differs from male pattern baldness, which blood tests matter, and why you should test before supplementing.

  • Hair Loss After Transplant

    This guide is for men who had a hair transplant and are still seeing thinning around it. It explains the difference between normal shedding, shock loss, and ongoing male pattern baldness, whether finasteride is required, and how to tell if you need a second procedure.

  • Stopping Minoxidil

    This guide is for men considering stopping minoxidil who want to know what to expect. It covers the shedding timeline, why hair can look worse than before treatment, whether tapering helps, and what happens if you restart later.

Hairloss AI

AMR Holding B.V.

Oostzaanstraat 8, 1013 WK Amsterdam, Netherlands

All rights reserved - Copyright © 2026