Deodorant vs. antiperspirant: aluminium salts, how they work and the alternatives
Deodorants fight odour, antiperspirants reduce sweating. How to tell them apart on the INCI list, what aluminium salts do, what the EU safety assessment says and which ingredients “aluminium-free” products use instead.
Updated: 31 October 2026 · Reviewed by: Kamil Pyziak
Two different jobs
Sweat itself is almost odourless. Underarm odour develops when bacteria on the skin break down components of sweat, especially from the apocrine glands that become active at puberty. That gives two ways to tackle it: reduce the odour, or reduce the sweat.
A deodorant works on odour: it masks it with fragrance, slows down the bacteria or the processes that create the smell, or absorbs odour molecules. An antiperspirant reduces the amount of sweat that reaches the skin surface. Most antiperspirants also contain deodorising ingredients, which is why packs often say “antiperspirant deodorant”. In the EU both are cosmetic products.
How aluminium salts reduce sweating
Antiperspirants rely on aluminium salts. They dissolve in sweat and form a gel-like plug near the openings of the sweat ducts, temporarily reducing the flow of sweat. The effect wears off as the skin renews itself and the plugs are washed away. On INCI lists – which use the American spelling “aluminum” – look for Aluminum Chlorohydrate, Aluminum Sesquichlorohydrate, Aluminum Zirconium Tetrachlorohydrex GLY or Aluminum Chloride.
Aluminium zirconium complexes are listed in Annex III of the EU Cosmetics Regulation with maximum concentrations and a mandatory warning not to apply to irritated or damaged skin. Aluminium salts can sting on freshly shaved or broken skin, and they are often associated with yellowish marks on clothing.
What the science says about aluminium
Aluminium in antiperspirants has been discussed for years, including suggested links with breast cancer and Alzheimer’s disease. Scientific and health bodies have not established that antiperspirants cause these diseases. In 2020 the EU Scientific Committee on Consumer Safety (SCCS) concluded that aluminium compounds are safe in antiperspirants, toothpastes and lipsticks at the levels it assessed, taking into account other sources of aluminium exposure such as food.
If you have specific health concerns, kidney disease or questions about a diagnosis, speak to a doctor. Heavy sweating that disrupts daily life (hyperhidrosis) is a medical matter, and a doctor can explain the options.
Deodorant ingredients without aluminium
Aluminium-free deodorants combine several approaches. Fragrance (Parfum) and essential oils mask odour. Alcohol Denat. and some other ingredients have an antimicrobial effect. Triethyl Citrate is used because it inhibits enzymes involved in odour formation, while Zinc Ricinoleate binds odour molecules. Ethylhexylglycerin, Farnesol and Caprylyl Glycol are other ingredients with a deodorant function.
Powders and absorbent ingredients such as Zea Mays Starch, Silica or Kaolin can make the skin feel drier without blocking sweat. Sodium Bicarbonate (baking soda) and Magnesium Hydroxide are popular in “natural” deodorants; baking soda is alkaline and some people find it irritating, especially on freshly shaved skin.
Alum stones and “aluminium-free” claims
Deodorant crystals or alum stones are usually made from Potassium Alum or Ammonium Alum. These are aluminium salts too. They are mainly described as astringent and deodorising, and they are less studied as antiperspirants than aluminium chlorohydrate. Whether a product containing alum may be described as “aluminium-free” is debatable; the INCI list shows what it actually contains.
Also note that “0% aluminium salts” or “no aluminium” on the pack refers to antiperspirant actives. Some aluminium-containing ingredients with other functions, such as certain pigments or Alumina, can still appear in other products, so reading the full list is the only reliable check.
What the label does not tell you
The INCI list does not show the concentration of aluminium salts or how effective an antiperspirant is; words such as “48h” or “72h protection” are claims based on the manufacturer’s tests. It also does not tell you how your own skin and sweat will respond.
If a deodorant irritates, the cause may be fragrance, alcohol, baking soda or the aluminium salt itself. Comparing the full lists of products you tolerate and those you do not can help, and a dermatologist can investigate persistent reactions.