Hair growth reduction does not remove hair and it does not switch a follicle off. It works on timing — shortening the window in which a follicle is actively building a shaft, so the hair that comes back is shorter and finer than it would otherwise have been.
This page explains the growth cycle properly, then the FGF-5 pathway that the ungro Smooth Gel is built around, then why this formula has to be water-based when the Ingrown Hair Oil has to be anhydrous. It is honest about where the evidence is strong and where it is a supplier's rationale.
What is the hair growth cycle?
Every follicle on the body runs on a repeating cycle, independently of its neighbours. That is why body hair does not all fall out at once, and why waxing catches hairs at different lengths.
There are four phases.
- Anagen — growth. The follicle regenerates its lower segment, wraps a bulb around the dermal papilla, and the matrix cells inside divide and differentiate to build a hair shaft. This is the only phase in which the follicle's inferior segment exists at all. Duration varies enormously by body site: years for scalp hair, a few months for eyebrows and eyelashes.
- Catagen — regression. The shortest phase, lasting a few weeks. Cell division in the matrix stops. The lower follicle regresses through programmed cell death and eventually disappears, and the dermal papilla travels upward to sit against the bulge. The hair forms a hard white node at its base and becomes a club hair.
- Telogen — rest. The hair is complete but not growing. The follicle is dormant.
- Exogen — shedding. The old hair is released, making room for the next anagen. It is sometimes treated as a sub-phase of telogen.
These phases are described in StatPearls, Anatomy, Hair Follicle and StatPearls, Physiology, Hair.
What determines how long a hair gets?
Almost entirely, how long anagen lasts.
A hair grows at a fairly consistent rate — roughly a centimetre a month for scalp hair. Terminal length is therefore close to growth rate multiplied by anagen duration. Scalp hair reaches the length it does because scalp anagen runs for years. An eyelash stays short because its anagen runs for a matter of months, not because eyelashes grow more slowly.
Two things follow, and they set the boundaries of the entire category.
Follicle count is fixed. No new hair follicles form after birth. Nothing applied to the skin adds or removes follicles.
Cycle duration is not fixed. It is under signalling control, and signalling is something a molecule can plausibly interact with. This is the only lever a topical product realistically has, and it is why the honest description of this category is hair growth reduction, not hair removal.
What is FGF-5, and why does it matter here?
Fibroblast Growth Factor 5 is one of the body's own signals for ending anagen. This is the interesting part, and almost nobody explains it to consumers.
Fibroblast growth factors are a family of secreted signalling proteins. They bind to receptors on the surface of cells and trigger internal cascades that change what those cells do. FGF-5 is the member of that family whose principal known job is to inhibit hair elongation by driving the follicle out of anagen and into catagen.
In plain terms: FGF-5 is the stop signal. When it accumulates in the right place at the right time, the matrix cells stop dividing, the lower follicle regresses, and the hair stops getting longer.
What happens when the stop signal is missing?
This is where the biology becomes unusually clean, because the natural experiment already exists.
In mice, animals carrying a non-functional Fgf5 gene — both the deliberately engineered null and the long-standing spontaneous "angora" mutation — grow abnormally long coats. The follicles are not more numerous or more active. They simply stay in anagen longer, because the signal telling them to stop never arrives properly.
In humans, recessive loss-of-function mutations in FGF5 cause familial trichomegaly: extremely long eyelashes. In the study that established this (Higgins and colleagues, Proceedings of the National Academy of Sciences, 2014), forearm hairs from affected individuals were significantly longer than those of controls, with a higher proportion of follicles in anagen. The same work showed FGF-5 inducing regression in cultured human hair follicles.
So the pathway runs in both directions. Remove FGF-5 signalling and hairs grow longer. Apply it to a follicle and it regresses. That is a well-characterised biological mechanism, and it is genuinely established.
The careful part. None of that is evidence about a cosmetic product. It is evidence that the pathway is real and that it does what it is said to do. What a topical peptide achieves at the follicle in normal skin is a separate question, addressed below.
What does "mimics FGF-5" actually mean?
Decapeptide-1 is a chain of ten amino acids, bioengineered rather than extracted from anything.
Peptides are short protein fragments. Proteins act on receptors through a small region of their surface — the part that physically fits the receptor — rather than through their whole bulk. A peptide mimetic is a short sequence designed to reproduce that fitting region well enough to engage the same receptor.
So "mimics FGF-5" means: a small molecule shaped to interact with the same receptor family that the body's own anagen-terminating signal uses, with the intention of nudging the follicle toward catagen sooner than it would have gone on its own.
What that claim rests on, precisely. The FGF-5 pathway is established biology, verified in humans and in animals. Decapeptide-1's activity as a mimetic of that pathway comes from in-vitro work carried out by the material's developer — cell and receptor studies showing the intended interaction.
In-vitro activity and a clinical outcome are not the same thing. A peptide that engages a receptor in a dish still has to survive in a formula, cross the stratum corneum, reach the relevant part of a living follicle, and arrive at a concentration that does something. Each of those is a real hurdle.
ungro's position is that the mechanism is sound and named honestly, that the supplier's rationale is described as a rationale, and that no independent clinical trial of this formula exists. A brand that tells you otherwise is telling you something it cannot support.
What is the cocoa ferment doing?
Lactobacillus/Cocoa Fruit Ferment Filtrate is a set of flavones isolated from cocoa fruit by fermentation. Flavones are a class of plant polyphenols; fermentation is used here as an extraction and conversion method, breaking down the fruit material to liberate compounds that are difficult to obtain otherwise.
The proposed contribution is complementary rather than duplicate. Where the peptide is proposed to act on the timing signal, the ferment is proposed to act on cellular proliferation within the follicle — the matrix has the highest mitotic rate of any tissue in the body, and moderating that rate would mean less shaft produced per unit of time.
Where the evidence is thinner. Noticeably thinner than for FGF-5. There is no equivalent to the trichomegaly genetics here: no human loss-of-function phenotype anchoring the pathway, and the supporting work is supplier-generated. It is a reasonable adjunct with a coherent rationale. It is not the reason to buy the product, and it is not presented as one.
Why does this one have to be water-based?
Format follows the active, not the marketing. This is the through-line of the whole ungro range, and it lands hardest here.
Decapeptide-1 is a peptide. Peptides are chains of amino acids, and amino acids carry charged and polar groups. That makes them water-soluble and, in practical terms, oil-insoluble. The cocoa ferment filtrate is likewise a water-phase material. Neither can be delivered in an anhydrous oil in any meaningful quantity.
Put the same reasoning next to the oil and the pair make sense as a set.
| Ingrown Hair Oil | Smooth Gel | |
|---|---|---|
| Target | The follicular opening and the hair shaft | The follicle's growth cycle |
| Key actives | Mandelic acid, jojoba, squalane, bisabolol, oat and Bacillus ferment | Decapeptide-1, cocoa fruit ferment filtrate |
| Solubility of those actives | Lipophilic or partly lipophilic | Water-soluble |
| Format the chemistry requires | Anhydrous oil | Water-based gel |
| Why that format | The infundibulum is sebum-filled; like dissolves like | The actives will not dissolve in oil at all |
| Preservative | Not required — no water present | Required, without exception |
| Realistic outcome | Fewer trapped hairs, less inflammation | Finer, shorter, slower regrowth |
Most of this category is sold as an oil regardless of what is in it, because oils feel considered and photograph well. Choosing the format first and then finding actives that tolerate it is backwards. The longer version of this argument is at why an oil-soluble acid reaches an ingrown hair that a water-based one can't.
How does the rest of the formula get the active where it needs to go?
Aqua, Glycerin, Betaine, Lactobacillus/Cocoa Fruit Ferment Filtrate, Decapeptide-1, Ethylhexylglycerin, Phenoxyethanol, Ethoxydiglycol, Xanthan Gum, Sodium Hyaluronate, Aloe Barbadensis Leaf Juice.
Eleven ingredients. One active pairing, and a base built to deliver it.
Ethoxydiglycol, and the delivery problem
The stratum corneum is a barrier by design. Its whole evolutionary purpose is to keep things out, and it is very good at it. A water-soluble molecule dropped onto intact skin in plain water will mostly stay on the surface.
Ethoxydiglycol is a solvent used at low levels for two related jobs. It keeps the active fully in solution rather than allowing it to associate or drop out over the life of the product, and it improves the partitioning of that active into the upper layers of the skin.
It is worth being clear about the limits. Improved partitioning is not the same as guaranteed delivery to the dermal papilla. It improves the odds. A well-chosen active that stays on the surface is a wasted one, and a solvent is how a formulator reduces that risk.
Xanthan gum, and why a gel suits this use
Xanthan gum is a polysaccharide produced by fermentation, and one of the most widely used gelling agents in cosmetics. It builds viscosity in a water phase.
Viscosity is a functional requirement here, not a texture preference. The Smooth Gel is designed for frequent, targeted use — often on a jawline or upper lip, often daily, applied with a roller. A watery liquid runs off a vertical surface before it can be absorbed. A gel stays where it is put, which means the dose that reaches the intended area is the dose you applied.
A gel also dries down without an occlusive film, which matters for something worn under makeup or applied straight after shaving.
Glycerin, betaine, sodium hyaluronate and aloe
These are here because of what the skin using this product has been through.
Anyone shaving, threading, waxing or plucking the same area every day or two is imposing repeated mechanical stress on the stratum corneum. Each pass removes some surface cells along with the hair. The barrier is thinner, transepidermal water loss rises, and the skin is measurably more reactive than untreated skin.
Glycerin and betaine are humectants: they hold water within the stratum corneum rather than sealing it in the way an oil would. Betaine is derived from sugar beet.
Sodium hyaluronate is the salt form of hyaluronic acid — a molecule the skin already produces — and it is smaller and more stable than the acid itself. It is why a water gel can feel cushioned rather than tight as it dries.
Aloe barbadensis leaf juice is soothing on skin that has just been through hair removal.
None of these affect hair growth. Their job is to make daily use on compromised skin tolerable, which is a precondition for a product that only works if it is used consistently.
Why does a water-based product have to be preserved?
Because microorganisms need water, and a water gel is an excellent place for them to live.
Bacteria, yeasts and moulds require available water to metabolise and reproduce. An anhydrous oil offers none, which is why the Ingrown Hair Oil carries no preservative. A gel that is mostly water, kept in a warm bathroom, opened daily, applied with a roller that touches skin and goes back into the bottle, offers a great deal.
The system here is phenoxyethanol with ethylhexylglycerin. Phenoxyethanol does the preserving across a broad range of organisms. Ethylhexylglycerin is a boost: it disrupts microbial cell membranes, which increases the efficiency of the phenoxyethanol and means less of it is needed for the same protection. It also conditions skin.
It is one of the best-established and best-tolerated modern preservative systems in cosmetic chemistry, and it is used here for that reason rather than despite it.
The point worth stating outright: an unpreserved water gel would be the more dangerous product, not the purer one. Contaminated cosmetics applied to freshly shaved skin — skin with a compromised barrier and often microscopic breaks in it — are a genuine infection route. Removing the preservative from this formula would not make it gentler. It would make it a risk.
What this product does not do
This section is here rather than in small print at the bottom, because it is the part most likely to matter to whoever is reading.
- It does not remove hair. It is not a hair removal method and it does not replace one. You will still shave, wax, thread or epilate.
- It is not permanent. It acts on cycle timing. Stop using it and follicles resume their normal cycle, and regrowth returns to what it was. Nothing is destroyed and nothing is switched off for good.
- It is not a treatment for hirsutism, PCOS, or any hormonal condition. Excess hair growth driven by endocrine causes is a medical matter and needs medical assessment. A cosmetic product does not address the underlying driver, and using one instead of getting a diagnosis is the wrong trade.
- It is not fast. It works through the cycle, and the cycle takes as long as it takes. Anything promising a difference in days is not describing this mechanism.
- Results vary, genuinely. Cycle length, hair thickness and hormonal environment all differ between people and between body sites.
If unwanted hair growth is new, rapid, or accompanied by other changes, see a GP. For permanent reduction, DermNet's summary of hair removal techniques sets out what actually falls into that category and what does not.
Where does the evidence sit, honestly?
| Claim | Status |
|---|---|
| Hair length is determined by anagen duration | Established dermatological science |
| FGF-5 terminates anagen and drives catagen | Established; confirmed by human and animal loss-of-function genetics |
| Loss of FGF-5 function produces abnormally long hair | Established; trichomegaly in humans, angora phenotype in mice |
| Decapeptide-1 engages that pathway in vitro | Supplier in-vitro rationale |
| Cocoa flavones moderate follicular proliferation | Supplier rationale; thinner evidence base |
| Topical application produces measurable reduction in this formula | Not independently trialled. Stated as expectation, not as proof |
| New follicles can be created or destroyed topically | False. No follicles form after birth, and none are removed by a cosmetic |
Publishing that table costs ungro something. Not publishing it would cost more.
Where to read next
- The science of ingrown hairs — follicular anatomy, the two re-entry routes, and why the oil is anhydrous.
- What an ingrown hair actually is — the shorter explainer.
- What's in it, and why — both formulas, ingredient by ingredient.
- How hair growth reduction actually works (and what it can't do).
- Why an oil-soluble acid reaches an ingrown hair that a water-based one can't.
Sources
- Martel JL et al. Anatomy, Hair Follicle. StatPearls
- Hoover E et al. Physiology, Hair. StatPearls
- Hair removal techniques. DermNet
- Higgins CA, Petukhova L, Harel S, et al. FGF5 is a crucial regulator of hair length in humans. Proc Natl Acad Sci USA. 2014;111(29):10648–53.
- Hébert JM, Rosenquist T, Götz J, Martin GR. FGF5 as a regulator of the hair growth cycle: evidence from targeted and spontaneous mutations. Cell. 1994;78(6):1017–25.
The two FGF5 papers are named rather than linked, because ungro only publishes links it has verified resolve. Where no source is cited above, the statement reflects settled cosmetic-science or dermatological consensus rather than a single paper. Nothing on this page is a medical claim, and no ungro product treats or cures any condition.
Published by the ungro lab.