Aluminium-Free Deodorant Doesn't Reduce Sweat. We Sell One Anyway.

Our deodorant does not reduce sweat. We sell it, we screened it at 9.0, and the "Aluminum-free" chip sitting on its product page is, read honestly, a notice that it cannot do the thing most people think they are buying.

That is not a formulation failure. In the United States, a product that reduces sweat is a drug, regulated under 21 CFR Part 350, and every active permitted in that monograph is an aluminium salt. Remove them and you have removed the entire approved mechanism. Our own product data admits it more plainly than our marketing does: the hero ingredient field on twiling-deospray-clean-fresh reads "Zeolite + Zinc (Odor Absorbers) + Green Tea & Centella".

Our own hero-ingredient field on twiling-deospray-clean-fresh says odour absorbers, and it is the most accurate line on the page.

Two products, and one of them is a drug

The FDA has a plain-language page for exactly this problem, called "Is It a Cosmetic, a Drug, or Both? (Or Is It Soap?)". A cosmetic is intended to cleanse, beautify or alter appearance. A drug is intended to affect the structure or function of the body. Sweating is a function of the body. Smelling is not.

What makes that page worth reading is the example the FDA reaches for. It names "deodorants that are also antiperspirants" as its own illustration of a product that meets both definitions at once, sold in one can, regulated in two directions.

21 CFR 350.10 is where the second direction gets specific. Aluminium chlorohydrate and its chlorohydrex forms are permitted up to 25%. Aluminium zirconium chlorohydrate and octachlorohydrex forms go up to 20%. Aluminium chloride hexahydrate is capped at 15% and only in a nonaerosol aqueous solution. Read the list top to bottom and it is aluminium the whole way down.

Then §350.50(b) sets the price of the language. A 20% reduction in sweat supports "effective" or "all day protection". A 30% reduction is what you need before you may print "extra effective".

Twenty percent.

That is the bar a regulated, aluminium-loaded, monograph-compliant antiperspirant has to clear before it may call itself effective, and it is worth holding on to while reading anything that promises more.

We could not verify the test methodology underneath those two numbers. The regulation states the 20% and 30% thresholds, but we were unable to confirm the gravimetric protocol behind them or the number of subjects it takes. We are not going to describe a hot-room pad-weighing procedure we did not read. The thresholds are real and in force; the study design that produced them is a gap in what we can tell you.

Korea handles the same fault line with a completely different machine, and it is worth resisting the urge to translate one into the other. There is no Korean equivalent of the OTC monograph. Instead the MFDS document 「의약외품 범위 지정」 defines 액취방지제 as an external preparation used to prevent underarm odour through suppression of sweat generation, and puts it in the 의약외품 tier, quasi-drugs, which require MFDS approval before sale. An ordinary deodorant that masks or absorbs odour without suppressing sweat stays in 화장품, cosmetics, and needs no such approval.

Different architecture, same crack down the middle. Suppress sweat and a regulator wants to see your file, in Silver Spring or in Cheongju alike.

What aluminium does inside a duct

The mechanism was watched directly in a 2021 Scientific Reports paper that ran aluminium chlorohydrate against sweat components in a microfluidic channel. Polycationic aluminium clusters meet anionic sweat proteins and aggregate electrostatically. The aggregates nucleate at the duct wall and build inward.

The word that matters in that paper is obstruct. Not seal, and not shut off. An eccrine pore with an aluminium aggregate in it is a partially blocked pipe, and a partially blocked pipe still passes fluid, which is the honest reason the regulatory threshold for "effective" is 20% and not 90%.

Nothing in an aluminium-free product does this. Zeolite is an aluminosilicate mineral with a porous cage structure and it adsorbs volatile molecules out of the air near your skin. Zinc salts bind odorants and suppress bacteria. Triethyl citrate, common in the natural deodorant category, hydrolyses on skin to citric acid, lowers local pH, and deactivates the bacterial lipases and esterases that generate smell. That last description comes from a Jungbunzlauer technical document, which is a supplier publication rather than peer-reviewed work, and we flag it as such because the same document is candid about the limit: triethyl citrate addresses odour, not sweat volume.

We went looking for a counterexample, some aluminium-free actives system with a measured reduction in sweat output, held to anything like the §350.50 standard.

We found none: not in the SCCS review, not in the supplier literature.

The smell is bacterial, and that part is addressable

Fresh apocrine secretion is close to odourless. The smell is manufactured on your skin, by bacteria, out of precursors your glands supply, and the 2013 FEMS Microbiology Ecology review by James and colleagues lays out both halves of the chemistry. Apocrine Nα-acyl-glutamine conjugates are cleaved by a bacterial aminoacylase, releasing 3-methyl-2-hexenoic acid, the sour-sharp component. S-cysteinylglycine conjugates are cleaved by a C-S beta-lyase, releasing thioalcohols including 3-methyl-3-mercaptohexan-1-ol, which is the oniony one and is perceptible at very low concentrations. The organism doing most of this is Corynebacterium. Staphylococcus is abundant in the same armpit and shows no direct correlation with odour intensity, which is a useful correction to the general "kill the bacteria" framing, because the abundant genus and the smelly genus are not the same genus.

So an odour absorber is working on a real mechanism. Adsorb the thioalcohol, drop the pH the enzyme needs, reduce the Corynebacterium load, and the shirt smells better at 6pm.

The shirt is still wet, because zeolite at position 4 never gets near an eccrine duct.

Those are two separate complaints and the aisle keeps selling them as one. If your problem is a damp mark on grey cotton in a 2pm meeting, an odour absorber will not fix it, and no amount of zeolite will. If sweating is heavy enough to interfere with work or sleep, that is hyperhidrosis and belongs with a clinician, not with a shopping decision.

The fear that built this category does not survive its own evidence

The SCCS reviewed aluminium in cosmetics again in 2019, opinion SCCS/1613/19, and assessed use levels up to 6.25% in non-spray and 10.6% in spray antiperspirants and deodorants. The margins of safety it calculated were roughly 25,714 for non-spray and roughly 30,000 for spray. Those are not marginal numbers.

On the claim that drove most of the market, the SCCS wrote that "the epidemiological studies do not support the hypothesis that the use of aluminium-containing cosmetics may affect the risk of breast cancer". On the older fear, it wrote that a causal relationship with Alzheimer's disease "has not yet been proven".

The Alzheimer's Drug Discovery Foundation is blunter: "There is no consistent or compelling evidence to associate aluminum with Alzheimer's disease." Their summary points at a meta-analysis of more than 6,000 people that found regular use of aluminium-containing antacids, a far larger exposure than any armpit receives, not associated with Alzheimer's. Occupational meta-analyses of workers breathing aluminium dust found no association either. And aluminium salts are poorly absorbed through intact skin in the first place.

There is a real qualifier and we would rather print it than be caught omitting it. The SCCS's margin for total combined systemic body burden, which stacks cosmetic aluminium on top of dietary and other sources, comes out around 2,400. That is an order of magnitude below the ~25,000 to ~30,000 figures for a single product used on its own. It did not change the committee's conclusion, and it is the number a careful reader should be looking at rather than the headline one.

Which puts us in an awkward position. The category our 9.0-scored deospray sits in was built on a worry that the SCCS and the ADDF both decline to support, and we are not going to pretend otherwise to protect a listing.

What our screening found

The practical takeaway

If the thing bothering you is wetness, buy an antiperspirant with an aluminium salt in it, and buy it without guilt, because the SCCS margins and the Alzheimer's evidence do not support the fear that pushed you off it. Aluminium chlorohydrate at monograph strength is the only mechanism anyone has shown to work.

If the thing bothering you is smell, aluminium-free is a fair choice, and our deospray is a fair version of it, propellants and all. Zeolite and zinc are aimed at the Corynebacterium chemistry, which is where the smell actually comes from.

What you should not do is buy an aluminium-free product expecting dryness, then conclude that your body is unusual when the shirt still marks. That expectation was sold to you by a chip on a label, and chips are exactly the kind of claim we keep testing against what is behind them. Our screening criteria grade ingredients, not promises, which is why a 9.0 here means clean composition and nothing at all about sweat volume.