What is the difference between an antiperspirant and a deodorant?

An antiperspirant reduces sweat: its aluminum salts form a temporary plug in the eccrine sweat ducts. A deodorant addresses odor by acting on the skin bacteria that create smell, or by masking it. The FDA regulates antiperspirants as drugs and odor-only deodorants as cosmetics.

How do aluminum salts reduce sweating?

They form a temporary plug near the top of the eccrine sweat duct. Laboratory work suggests aluminium polycations aggregate the person's own sweat proteins into a membrane that occludes the duct in two stages, nucleation then growth. The plug is superficial and is shed as skin renews, which is why reapplication is expected.

Does sweat itself smell?

Fresh sweat is almost entirely odorless. Body odor appears when skin bacteria, notably some Corynebacterium species, metabolize compounds in apocrine sweat into volatile molecules such as short-chain fatty acids and thioalcohols. That bacterial step, not the sweat, is what deodorants target.

Do deodorants reduce sweating?

A deodorant that only addresses odor does not reduce how much you sweat; it works on smell. Only an antiperspirant is designed to reduce sweat volume. Some products combine both functions, and those are regulated as antiperspirant drugs for their sweat-reducing action.

Why is an antiperspirant a drug but a deodorant a cosmetic?

Because an antiperspirant changes a body function (sweat production), the FDA classifies it as an over-the-counter drug under 21 CFR part 350, with defined active ingredients and concentration limits. A product that only affects odor is regulated as a cosmetic.

Is the sweat-duct plug permanent?

No. It sits near the surface of the duct and is shed as the outer skin layer naturally renews, so the effect is temporary. Antiperspirants are designed to be reapplied rather than to change the sweat glands permanently.

Research

How Antiperspirants and Deodorants Work: The Science

Antiperspirants and deodorants do two different jobs. An antiperspirant is regulated as a drug and is designed to reduce sweat: its aluminum salts form a temporary plug inside the eccrine sweat ducts so less sweat reaches the skin surface. A deodorant works on smell, not wetness. Sweat itself is nearly odorless, and odor appears only after skin bacteria break it down, so deodorants target those bacteria or mask the result. This page explains both mechanisms from primary sources. It is label-literacy only: it describes how these products are designed to work, and does not recommend, endorse, or rank any product.

By the Sweat Explained Editorial Team · Published 2026-07-13 · Last reviewed 2026-07-13 · Educational information, not medical advice.

Key statistics at a glance

eccrine ducts
where aluminum-salt antiperspirants form a temporary plug that reduces sweat reaching the skin surface
NCI; Bretagne 2017
up to 15%
maximum aluminum chloride concentration the FDA permits in a nonaerosol antiperspirant (as the hexahydrate)
FDA 21 CFR 350.10
2 stages
nucleation then growth: how aluminium polycations aggregate sweat proteins to occlude the duct
Bretagne 2017, Soft Matter
bacteria, not sweat
deodorants act on odor-causing skin bacteria; fresh sweat is almost entirely odorless on its own
ASM 2021
drug vs cosmetic
the FDA regulates antiperspirants as over-the-counter drugs and odor-only deodorants as cosmetics
FDA 21 CFR 350

Antiperspirant vs deodorant: the core difference

The two words are often used interchangeably, but they describe different actions. An antiperspirant is meant to reduce how much you sweat; a deodorant is meant to reduce or mask odor. The US Food and Drug Administration draws the same line in regulation: it defines an antiperspirant as "a drug product applied topically that reduces the production of perspiration (sweat) at that site." A product that only addresses smell is treated as a cosmetic.

That distinction matters when reading a label. If a product lists an aluminum-based "active ingredient" and a "Drug Facts" panel, it is functioning as an antiperspirant. If it only lists odor-control or fragrance ingredients, it is functioning as a deodorant. Many everyday products combine both roles.

How antiperspirants reduce wetness

Antiperspirants use aluminum salts, such as aluminum chloride, aluminum chlorohydrate, or aluminum-zirconium compounds, as their active ingredient. The National Cancer Institute describes the basic action plainly: these compounds "form a temporary 'plug' within the sweat duct that stops the flow of sweat to the skin's surface." The plug forms in the eccrine glands, the sweat glands distributed across most of the body that produce watery sweat for temperature control.

The classical explanation was that aluminium ions simply precipitate and physically block the duct opening. More recent laboratory work has refined this. A 2017 study in Soft Matter that watched the process under microfluidic conditions reported that "pore occlusion occurs as a result of the aggregation of sweat proteins by aluminium polycations," and described two stages: a nucleation stage in which protein-and-polycation aggregates bind to the duct wall and form a thin membrane, and a growth stage in which that membrane collects more proteins carried by the flowing sweat. In other words, the plug is built partly from the person's own sweat proteins.

This effect is temporary and superficial. The plug sits near the top of the duct and is shed as the skin's outer layer naturally renews, which is why antiperspirants are designed to be reapplied. Because they are regulated as drugs, the FDA sets concentration limits: for example, aluminum chloride is permitted up to 15% (calculated as the hexahydrate) in a nonaerosol product.

Where body odor actually comes from

Deodorants work on a completely different problem. Freshly produced sweat has almost no smell. The odor associated with underarms comes from bacteria that live on the skin and feed on the richer secretions of the apocrine glands concentrated there. As the American Society for Microbiology puts it, this fluid "is naturally almost entirely odorless. It is only when members of the skin microbiota metabolize these secretions that they produce the malodorous byproducts, which cause body odor."

Specific bacteria drive this. Members of the genus Corynebacterium, among others, convert odorless precursors in sweat into volatile compounds, including short-chain fatty acids and thioalcohols, that the nose registers as body odor. One well-studied example, a thioalcohol produced by Staphylococcus hominis, is described as making underarms "smell like rotten onions or meat."

Deodorants intervene at this bacterial step rather than at the sweat gland. In general terms, "deodorants contain chemicals that kill skin flora and block production of stinky byproducts," whereas "antiperspirants reduce the amount of sweat produced by clogging sweat glands." Some deodorants also use fragrance to mask any remaining odor. Because a deodorant changes smell rather than sweat output, it does not reduce wetness.

The two products side by side

This table summarizes the verified differences in what each product targets and how it is regulated. It is descriptive, not a recommendation of one over the other.

Antiperspirant vs deodorant: mechanism and regulatory status
Feature	Antiperspirant	Deodorant
What it targets	Sweat (wetness)	Odor
How it is designed to act	Aluminum salts form a temporary plug in eccrine sweat ducts	Reduces or masks odor-causing skin bacteria and their byproducts
Typical active/functional ingredient	Aluminum chloride, aluminum chlorohydrate, aluminum-zirconium salts	Antimicrobial and/or fragrance ingredients
Effect on sweat volume	Reduces sweat reaching the surface	No direct effect on sweat volume
FDA classification	Over-the-counter drug (21 CFR 350)	Cosmetic (if it only affects odor)

Combination "antiperspirant/deodorant" products do both jobs and are regulated as drugs for their antiperspirant action.

Why one is a drug and the other a cosmetic

The regulatory split follows the mechanism. Because an antiperspirant changes a body function (sweat production), the FDA treats it as an over-the-counter drug, governed by the antiperspirant monograph in 21 CFR part 350. That monograph lists the aluminum active ingredients allowed and the maximum concentrations permitted. A deodorant that only affects odor is a cosmetic, which is regulated differently and does not carry a Drug Facts panel.

This is why a store shelf can hold three kinds of product that look similar: pure antiperspirants (reduce sweat), pure deodorants (address odor), and combination products that do both. Reading the ingredient panel tells you which mechanism you are actually buying.

What this means in plain language

If the goal is less wetness, that is the job an antiperspirant is designed to do, through the eccrine-duct plugging described above. If the goal is less smell, that is the job a deodorant is designed to do, by acting on skin bacteria. A single product can carry out both roles, but they are distinct mechanisms, and neither one "cancels" sweating altogether: antiperspirants reduce the sweat that reaches the surface rather than switching the glands off.

None of this is medical advice, and it is not a recommendation to use or avoid any product. Sweating and body odor are usually normal. If sweating is heavy enough to interfere with daily life, or if a sudden change in sweating or odor is worrying, a clinician can help sort out the cause and the options.

Methodology and limitations

This page describes mechanism only, drawn from primary and authoritative sources: the FDA over-the-counter antiperspirant regulations (21 CFR part 350), the National Cancer Institute's description of the sweat-duct plug, a peer-reviewed microfluidics study of pore occlusion (Bretagne et al., Soft Matter 2017), and a review of the microbiology of body odor from the American Society for Microbiology. Each quoted statement was traced to its source page and confirmed.

Limitations: the exact molecular details of how aluminum salts occlude sweat ducts are still an area of active research, and the classical precipitation model and the newer protein-aggregation model are both described here rather than treated as settled. Regulatory definitions are US-specific; other countries classify these products differently. This page explains how the products are designed to work and does not evaluate how well any specific product performs, nor does it recommend or endorse any product. It is general education, not medical advice.

Frequently asked questions

What is the difference between an antiperspirant and a deodorant?: An antiperspirant reduces sweat: its aluminum salts form a temporary plug in the eccrine sweat ducts. A deodorant addresses odor by acting on the skin bacteria that create smell, or by masking it. The FDA regulates antiperspirants as drugs and odor-only deodorants as cosmetics.
How do aluminum salts reduce sweating?: They form a temporary plug near the top of the eccrine sweat duct. Laboratory work suggests aluminium polycations aggregate the person's own sweat proteins into a membrane that occludes the duct in two stages, nucleation then growth. The plug is superficial and is shed as skin renews, which is why reapplication is expected.
Does sweat itself smell?: Fresh sweat is almost entirely odorless. Body odor appears when skin bacteria, notably some Corynebacterium species, metabolize compounds in apocrine sweat into volatile molecules such as short-chain fatty acids and thioalcohols. That bacterial step, not the sweat, is what deodorants target.
Do deodorants reduce sweating?: A deodorant that only addresses odor does not reduce how much you sweat; it works on smell. Only an antiperspirant is designed to reduce sweat volume. Some products combine both functions, and those are regulated as antiperspirant drugs for their sweat-reducing action.
Why is an antiperspirant a drug but a deodorant a cosmetic?: Because an antiperspirant changes a body function (sweat production), the FDA classifies it as an over-the-counter drug under 21 CFR part 350, with defined active ingredients and concentration limits. A product that only affects odor is regulated as a cosmetic.
Is the sweat-duct plug permanent?: No. It sits near the surface of the duct and is shed as the outer skin layer naturally renews, so the effect is temporary. Antiperspirants are designed to be reapplied rather than to change the sweat glands permanently.

Sources

Primary peer-reviewed studies and official sources first, then reviews and institutional framing (secondary).

US Food and Drug Administration. 21 CFR 350.3: Definitions (Antiperspirant Drug Products for Over-the-Counter Human Use). Code of Federal Regulations, Title 21, Part 350. Defines an antiperspirant as a topical drug that reduces perspiration. Regulation
US Food and Drug Administration. 21 CFR 350.10: Antiperspirant active ingredients. Lists permitted aluminum active ingredients and concentration limits (e.g., aluminum chloride up to 15% as the hexahydrate). Regulation
National Cancer Institute. Antiperspirants/Deodorants and Breast Cancer. NCI fact sheet describing the temporary sweat-duct 'plug' mechanism. Fact sheet
Bretagne A, Cotot F, Arnaud-Roux M, Sztucki M, Cabane B, Galey JB. The mechanism of eccrine sweat pore plugging by aluminium salts using microfluidics combined with small angle X-ray scattering. Soft Matter. 2017. PMID 28485735. PubMed
American Society for Microbiology (Ashley Hagen). Microbial Origins of Body Odor. Reviews how skin bacteria (including Corynebacterium) convert near-odorless sweat into malodorous compounds; contrasts deodorants and antiperspirants. (secondary) Article

How to cite this page

Sweat Explained. How Antiperspirants and Deodorants Work: The Science. Published 2026-07-13; last reviewed 2026-07-13. Available at: https://sweatexplained.com/research/how-antiperspirants-and-deodorants-work-evidence

Please cite the original studies for the underlying figures. Journalists are welcome to link to this page; the charts are original renderings of the cited data.