Deodorants and Antiperspirants
Although people have sweat glands all over their bodies, there is a high concentration of sweat glands in the underarm area. The eccrine glands cool off the body when it is hot and only expel water and salt. The apocrine glands, on the other hand, are the cause of body odor, as they excrete fat and proteins. When these secretions reach the surface of the skin, they react with bacteria and create an odor. 

Deodorants, which do not prevent sweating, target the bacteria that is present on underarm skin by using ingredients like triclosan to create an uninhabitable environment. Without the bacteria, the secretions from the apocrine gland cannot interact and produce a smell. Antiperspirants, however, use ingredients like aluminum and zirconium to plug the sweat glands. Without sweat, the bacteria have nothing to feed on and no odor is produced.

The main drawback of these products are the ingredients that are being used. Aluminum, for example, has been shown to create oxidative stress on cells, causing DNA damage and contributing to cell aging. Furthermore, it accrues in the bones, brain, liver, and kidneys and has been shown to cause granulomas.

Many underarm products also use propylene glycol, a petroleum-based ingredient that gives the products its slickness. This ingredient has been linked to damage of the central nervous system, liver, and heart. Other concerning ingredients include phthalates, triclosan (a probable carcinogen), silica, and steareth-n. In addition to harmful ingredients, the plugging of glands means that the body is not able to purge toxins from the body.

Natural Underarm Products
Much like other natural skin care products, natural deodorants are a good investment for clients that want to avoid applying toxic ingredients on their skin. These products typically come in either a roll-on or cream format and contain ingredients such as shea butter, baking soda, arrowroot powder, cocoa seed butter, coconut oil, kaolin clay, essential oils, and vitamin E. While there is not an all-natural antiperspirant available, many people find that some natural underarm products are effective at keeping them dry. These products use plant extracts and baking soda to kill bacteria and essential oils to provide a pleasant smell.

When educating clients about the benefits of using natural underarm products, many professionals may be met with the protestation that natural products do not work as well as regular deodorants. It is important for clients to recognize that every product will interact with their body in a different way. Although one natural underarm product does not work for them, there is a huge variety of other natural deodorants that can provide the desired result.

References
Chemical of the Day. (2012, September). Dangers of Aluminum.
Clark, J., & How Stuff Works Health. (n.d.). What's the difference between deodorant and antiperspirant?
Norek, D. (2011, August). Top five ingredients to avoid in deodorant.