Can Deodorant Change Your Skin Microbiome?

Many of us reach for our deodorant while getting ready in the morning to decrease our chances of stinky body odor, especially if we are going to be working out. It turns out that the microorganisms living on your skin may be responsible for your unpleasantly smelly armpits.

Our skin houses tiny microorganisms that make up the skin microbiome, including bacteria, fungi, and viruses, according to WebMD. There are different types of microbes residing on our skin depending on whether its surface is dry, oily, or moist (per News-Medical).

Most of these microbes are commensals, which are harmless microbes that benefit from living on our skin, and can benefit us by taking space and nutrition away from microbes that are actually harmful. As well as protecting us from our environment, our skin microbiome plays a role in fighting infection, regulating our immune system, and preventing inflammation. Various factors can affect the skin microbiome, including genetics, diet, and exposure to air pollution and UV light.

As reported in a 2021 study published in Scientific Reports, the skin microbiome can contribute to body odor due to there being odor-causing bacteria in the axillary microbiome. Interestingly enough, sweat itself is almost completely odorless. Body odor comes from the byproducts of microbes that metabolize the sweat (per the American Society for Microbiology). 

When you have body odor, deodorant makes your armpits smell a million times better. We never think too much about it, but how is putting on deodorant affecting these microbes on our skin? 

Some scientists have been interested in the impact that wearing deodorant has on the skin microbiome. In a 2016 article published in PeerJ, the researchers explored what happens to the skin microbiome when antiperspirant and deodorant are applied to the armpits.

Antiperspirants work by blocking the sweat glands that contribute to smelly armpits, whereas deodorants only cover up the smell. When most people think of deodorant, what they're really thinking about is antiperspirant, notes The Washington Post.

The 17 participants of the study were asked to use either antiperspirant, deodorant, or neither product before having swabs taken from their armpits during an experiment that was conducted over eight days. The presence of microorganisms on the skin of each participant was examined from these samples.

The researchers found that people who used antiperspirant products on the first day had fewer microbes than people who didn't apply the products, although the results contained a lot of variability. Interestingly, the participants who used deodorant on day one appeared to have even more microbes on average than the participants who didn't use either product. Even so, the number of microbes was minimal after all participants were told to use antiperspirant on the seventh and eighth days.

Julie Horvath, an author of the study, reports that these results suggest that the use of antiperspirant or deodorant might change the number of microbes growing on the skin. However, it's unknown whether this is helpful or harmful.