How does deodorant work?

Answer 1

I don't know completely how deodorant works, but I know the simple answer: Deodorant kills bacteria that make sweat smelly. Initially, sweat does not smell. But there is bacteria which thrives in hot, humid areas (such as a sweaty, hairy armpit), which somehow makes the odorless sweat become stinky (how, I don't know). Deodorant (whatever it's made of) kills these bacteria by inhibiting growth (antiseptic action!). What is the chemical formula of the active ingredient in deodorant? I don't know. I'd like to know, though, so someone please finish this off (and correct anything that does need correction. There's not much info online about deodorant. However, there's loads of info about antiperspirants and how they work!)

A bit more ... Here's a great breakdown of deodorants AND antiperspirants courtesy of eNotes: (If you want more information -- more than most people would ever need, including the history of deodorants and the manufacturing process, click on the link at the bottom of the page.)

Antiperspirant/deodorant (APD) sticks are used to reduce underarm wetness and control body odor. These products are made by blending active ingredients with waxes, oils, and silicones and molding the mixture into stick form. Body odor is primarily generated in the area under the arms where there is a high concentration of sweat glands. While sweat from these glands is initially odorless, it contains natural oils, called lipids, that provide a growth medium for bacteria living on the skin. These bacteria interact with the lipids, converting them into compounds that have a characteristic sweaty odor. Isovaleric acid, for example, is one chemical compound that gives sweat its smell. There are two primary types of products used to control body odor. The first, deodorants, reduce body odor by killing the odor-causing bacteria. These products do not affect the amount of perspiration the body produces. Antiperspirants, on the other hand, inhibit the activity of sweat glands so less moisture is produced. In addition to avoiding unpleasant wetness, these products also decrease odor because there is less sweat for the bacteria to act upon. While deodorants are considered to be cosmetic products because they only control odor, antiperspirants are actually drugs because they affect the physiology of the body. Although the exact mechanism of this physiological interaction is not fully understood, theory has it that antiperspirant salts form temporary plugs in some of the sweat gland openings so that moisture is not secreted. While this moisture reduction is not severe enough to interfere with normal body metabolism, it does noticeably lessen underarm wetness.

Antiperspirants consist of the active drug ingredients that control perspiration; gelling agents that form the stick matrix; and other ingredients, such as fragrance or colorants, that make the product aesthetically pleasing. The Food and Drug Administration (FDA) controls the active ingredients used in antiperspirants because they are legally classified as drugs. The FDA publishes an Over the Counter (OTC) Drug monograph that lists which ingredients are approved for use. The ingredients on this list are limited to aluminum chlorohydrate, aluminum chloride, aluminum sulfate, and aluminum zirconium complexes. Of these compounds, the most commonly used is aluminum zirconium tetrachlorohydrex glycine. Most of these materials are supplied as powders, and they are typically used at levels of 8-25% based on the weight of the finished product. The bulk of the formulation consists of waxy or fatty materials that are gelled to form a solid stick. Common examples include stearyl alcohol, cetyl alcohol, hydrogenated castor oil, and glyceryl stearate. These waxy materials are blended with lubricating oils and emollients such as cyclomethicone, which is a volatile silicone compound. These silicones are liquids at room temperature, but they quickly evaporate and are used because they leave the skin feeling smooth and dry. In addition, talc, starches, or other powders may be added to control stick consistency and to give the product a dry feel and a smooth payoff. Fragrance and colorants may be added to the formula to improve its odor or appearance. Some brands have fragrances that are time released. Other brands may add featured ingredients that contribute little functionality but are designed to increase consumer appeal.