Stopping the use of underarm hygiene products often stems from curiosity about the body’s natural state or a desire to avoid certain ingredients. For many, daily application is a long-standing habit meant to manage moisture and scent. Understanding what happens when this routine stops requires examining the skin’s biological processes and the products designed to modify them. This involves looking at physiological changes, the difference in product function, microbial shifts, and the factors that determine an individual’s unique scent profile.
The Immediate Consequence: Body Odor and Bacterial Activity
The return of noticeable body odor is the most immediate and predictable consequence of ceasing product use. Sweat itself is largely odorless; eccrine glands produce mostly water and salt for thermoregulation across the body. Odor-causing sweat comes from apocrine glands, which are concentrated in the armpits and groin. This apocrine sweat is rich in compounds like lipids, proteins, and steroids, which are released into the hair follicle.
These compounds become odorous only when they reach the skin surface and interact with local bacteria. Specific species, particularly Corynebacterium and Staphylococcus hominis, metabolize the odorless precursors in the sweat. This bacterial breakdown produces volatile organic compounds (VOCs) responsible for the characteristic smell. For instance, S. hominis generates pungent thioalcohols, which are associated with a distinct onion-like scent.
Corynebacterium species convert precursors into volatile fatty acids, which can have a more goat-like aroma. When the antibacterial or scent-masking agents of a product are removed, the existing bacterial population quickly resumes its metabolic activity without inhibition. The resulting odor profile is the natural, unchecked result of this bacterial ecosystem consuming apocrine secretions.
Deodorant Versus Antiperspirant: Understanding the Loss of Function
The effects of stopping use vary significantly depending on whether a person previously used a deodorant or an antiperspirant. Deodorants function primarily by addressing odor through two mechanisms. They contain fragrances to mask the scent and often include antimicrobial agents to reduce the population of odor-causing bacteria on the skin. Stopping a deodorant means immediately losing both the odor-masking scent and the ongoing suppression of microbial activity.
Antiperspirants, conversely, are classified as over-the-counter drugs because their active ingredients physically alter a bodily function. They typically use aluminum-based compounds that dissolve in the sweat and form temporary plugs in the sweat ducts. This physical blockage prevents the release of moisture, thereby reducing wetness. Stopping an antiperspirant results in the rapid return of full sweat production and the accompanying moist environment that bacteria thrive in.
Shifts in the Underarm Microbiome
Long-term use of underarm products significantly alters the ecology of the skin, known as the underarm microbiome. Studies have shown that individuals who regularly use antiperspirants tend to have a lower overall density of bacteria due to the product’s inhibitory effects. When use is discontinued, the microbiome must re-establish its natural state. This rebalancing period can result in an initial, temporary increase in odor intensity, often referred to as “rebound odor.”
This heightened smell occurs because the reduction of one bacterial group, such as Staphylococcaceae species, can create a niche for the odor-causing Corynebacterium species to flourish rapidly. The change in environment allows these specific odor-producing bacteria to briefly overgrow before the microbial community stabilizes. Full rebalancing of the underarm flora typically takes several weeks, after which the bacterial community settles into a more natural composition, often dominated by the Corynebacterium species associated with natural body odor.
How Diet and Genetics Influence Natural Body Odor
Once product use has ceased, the specific quality and intensity of an individual’s natural body odor are determined by genetics and dietary choices. Genetic variations play a profound role, particularly the single-nucleotide polymorphism in the ABCC11 gene. People with the non-functional variant of this gene produce significantly fewer odor-precursors in their apocrine sweat, resulting in minimal or no underarm odor. This variant is prevalent in East Asian populations, where a large majority of individuals carry it.
For individuals with the functional gene, which is common in European and African populations, diet becomes a noticeable factor. Compounds from certain foods are absorbed into the bloodstream and excreted through sweat, influencing the scent profile. Sulfur-rich foods, such as garlic, onions, and cruciferous vegetables, contain volatile sulfur compounds that can be released through the pores. Strong spices like cumin and curry, as well as red meat, can also contribute distinct odorous compounds to the sweat, altering the overall natural scent profile.