The short answer: what these products can and cannot do
Hair growth reduction works by shortening the phase in which a follicle is actively building a hair, so the hair that comes back is finer and shorter than it would otherwise have been. It does not remove hair, it does not stop hair, and it stops working when you stop using it.
That is the honest summary of the entire category. A hair growth inhibitor is a softening tool, not a removal tool. If you shave, wax or thread now, you will still shave, wax or thread while using one.
Everything below explains the mechanism properly, because the mechanism is genuinely interesting and almost nobody describes it to the person buying the product.
How does the hair growth cycle work?
Every follicle on your body runs on a cycle. It is not growing continuously. It grows, it shuts down, it rests, and it starts again.
Dermatology divides that cycle into three phases, set out in the standard reference on hair physiology.
| Phase | What the follicle is doing | Roughly how long it lasts | Why it matters here |
|---|---|---|---|
| Anagen (growth) | Cells in the hair bulb divide rapidly and push keratinised cells upward, building the hair shaft. The follicle is at its full size. | Two to six years on the scalp. Far shorter on the body — typically weeks to a few months, depending on the site. | This phase sets both length and thickness. It is the only phase a topical can meaningfully influence. |
| Catagen (transition) | Growth stops. The lower follicle regresses through programmed cell death and shrinks to about five-sixths of its normal diameter. A club hair forms at the base. | Around two weeks. | This is the exit door. Entering it earlier is the whole point of hair growth reduction. |
| Telogen (rest) | The follicle is dormant. No shaft is produced. The club hair sits in place until it is shed or pushed out by the next anagen hair. | Varies widely by site — from a few weeks for eyelashes to close to a year on the scalp. | Nothing is being built, so nothing can be softened. Timing is why results are never instant. |
Two things follow from that table, and they are the foundation of the rest of this article.
First: length and coarseness are functions of time in anagen. A follicle that stays in active growth for six months produces a longer, thicker hair than the same follicle staying in growth for six weeks. This is not a subtle effect. It is why the hair on your head is long and the hair on your forearm is not, despite both growing from broadly similar structures.
Second: your follicles are not synchronised. At any moment, some are in anagen, some in catagen, some resting. Only the ones currently in anagen are available to be influenced. That single fact explains every realistic timeline in this category.
So the lever is clear. Shorten anagen and the hair that grows is finer and shorter. That is what hair growth reduction means. Anyone using the phrase to mean something else is describing hair removal.
Can a peptide tell a follicle to end its growth phase early?
This is the most elegant mechanism in the category, and it is the one worth understanding.
Your body already has a signal for ending anagen. It is a protein called fibroblast growth factor 5, usually shortened to FGF-5. It is produced in the outer root sheath of the follicle during late anagen, and its job is to push the follicle out of growth and into catagen. It is, functionally, the body's own off switch for hair growth.
The evidence for that is unusually clean. Loss-of-function mutations in the FGF5 gene produce long-haired phenotypes across a long list of mammals, because follicles that never receive a proper stop signal simply stay in anagen for longer. In humans, researchers investigating families with familial trichomegaly — extremely long eyelashes — traced the trait to mutations in FGF5, and found hair elsewhere on the body was longer too, with a higher proportion of follicles sitting in the growth phase. The same work showed that applying FGF-5 to cultured human follicles induces regression.
So: less FGF-5 signalling, longer hair. More FGF-5 signalling, earlier exit from growth.
A bioengineered decapeptide — a short chain of ten amino acids, made rather than extracted — can be designed to mimic that signal. It is not FGF-5 itself, which is a far larger molecule. It is a small fragment shaped to speak the same language to the follicle, encouraging it to leave active growth earlier than it otherwise would.
Sitting alongside the peptide in the same complex are flavones derived from cocoa and obtained by fermentation. These work on a different part of the problem: they contribute by reducing cellular proliferation within the follicle. If the peptide is the signal to stop, the flavones make it easier to comply, by slowing the cell division that builds the shaft in the first place.
That pairing is the interesting part. One ingredient talks to the follicle's own timing mechanism. The other reduces the raw output while it is still running.
Why one mechanism rather than a stack of them?
Because the growth cycle is the one variable that applies everywhere.
Every follicle you have runs on that same three-phase cycle — face, shin, underarm and bikini line alike. A lever on anagen is therefore a lever on all of them, and very little else a topical could target has that reach. A mechanism that only applies to some sites on some people is a narrower thing than it sounds on a label.
It is also worth noting that the complex above is already doing two jobs rather than one: a signal to the follicle's timing, and a brake on the cell division that builds the shaft. That is not a single blunt instrument.
Adding a second, unrelated active would lengthen the ingredient list and give the label more to say. It would not make the mechanism work better. A formula is not stronger for having more names on it — which is worth holding on to in a category where the ingredient list is often the marketing.
What will a hair growth inhibitor not do?
This section matters more than the science, so read it before you buy anything in this category — from ungro or anyone else.
It will not remove hair. Nothing about slowing regrowth removes the hair already on your skin. You will still shave, wax, epilate or thread. A hair minimiser sits alongside your existing routine; it does not replace it.
It is not permanent. Follicles keep cycling. Stop applying the product and, over the following cycles, regrowth returns to whatever is normal for you. This is maintenance, in the same way moisturising is maintenance. The precedent is well established — the prescription cream used for unwanted facial hair also slows regrowth rather than removing hair, and must be continued indefinitely to hold the effect.
It is not laser or electrolysis. Those are energy-based methods that damage the follicle itself, and DermNet notes electrolysis may result in permanent hair loss while lasers require multiple treatments over months to years. A topical gel does nothing comparable and does not claim to.
It is not a treatment for hirsutism, polycystic ovary syndrome or any hormonal condition. If facial or body hair has changed noticeably, arrived quickly, or comes with other changes, that is a medical conversation, not a cosmetic one. A cosmetic product cannot diagnose or treat a hormonal cause, and using one instead of seeing a doctor is a bad trade. Our article on caring for skin with PCOS-related facial hair is about skin care around the issue, not about the hormones.
Anyone promising permanent reduction from a topical is overselling. If you see that claim, that alone tells you what the rest of the marketing is worth.
So — does a hair growth inhibitor really work? Within that boundary, the mechanism is real and the ingredients are doing identifiable things. Outside it, no topical does what a laser does.
How long before anything changes?
Longer than most people expect, and the growth cycle explains exactly why.
Only follicles currently in anagen can be influenced. The ones resting today are not listening. As they wake and re-enter growth, they come into range. So the effect builds across a full cycle rather than appearing after a fortnight.
Practically, that means four to six weeks of consistent daily use before you would fairly judge it, and longer on coarse hair or larger areas. Applying it for ten days and deciding is not a test of the product.
It also means consistency beats intensity. Twice-daily application for two months does more than heavy application for one week, because the point is to be present when each follicle restarts.
And it is maintenance, not a course of treatment. There is no finishing point after which the effect holds on its own.
Who gets the most out of it?
People who remove hair regularly and want to do it less often. If you shave two or three times a week, the realistic gain is finer regrowth and a longer, more comfortable gap between shaves.
People with sensitive skin who find frequent removal irritating. Fewer passes with a blade means less mechanical insult, and less insult means fewer bumps. If razor bumps are your main complaint, what they are and why they form is the more useful starting point.
People between laser sessions, using it as an adjunct rather than a substitute.
People it suits less well: anyone wanting hair gone, anyone unwilling to apply something daily for months, and anyone whose hair growth has changed suddenly and has not yet been checked by a doctor.
Why is ungro Smooth Gel a water-based gel?
Because the active is water-soluble, and the format follows the chemistry.
A decapeptide is a short chain of amino acids. Peptides are hydrophilic by nature — they dissolve in water, not in oil. The cocoa flavones it is paired with arrive as a ferment filtrate, which is water-based too. Putting either into an anhydrous oil would leave the active poorly dispersed and poorly delivered. A water-based gel is not a texture preference. It is the only sensible vehicle for these particular ingredients.
The contrast with the other product in the range makes the point. ungro's Ingrown Hair Oil is completely anhydrous, with no water at all, because its hero active works in the oil phase and its target sits inside a lipid-filled follicle. Same brand, opposite format, for the same reason: the active decides.
Format follows the active, not the marketing. If a brand sells every product in the same base regardless of what is dissolved in it, that tells you something about how the formulating was done.
ungro Smooth Gel is 50 ml for $49 NZD, or 10 ml for $19, made in small batches in New Zealand. You can find it at /products/smooth-gel, and the full ingredient list is published on the ingredients page — a product built on an argument about delivery should not ask you to take the delivery on trust.
Written by the ungro lab. ungro makes an ingrown hair oil and a hair-regrowth-softening gel, formulated by a cosmetic chemist and made in small batches in New Zealand. We do not make products that treat hirsutism or PCOS — the hormonal side of this is your doctor's territory. This article is general information, not medical advice.