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Armpits may seem simple, but neglecting their care can lead to sweaty, smelly outcomes. Personally, I’ve ruined countless t-shirts due to my perspiration mixing with antiperspirant, leaving stubborn stains. Some of these stains are permanent, forcing me to part with my favorite clothes.
This raises an important question for me and others who struggle with excessive sweating: What’s the ideal amount of deodorant or antiperspirant to use? The answer, unlike the simplicity of armpits, is more nuanced than it appears.
Understanding the Difference Between Deodorant and Antiperspirant
First, it’s important to understand the difference. Deodorant and antiperspirant are not the same, at least in theory (though most modern deodorants are combined with antiperspirants, so you typically get both). Antiperspirants contain aluminum compounds that block sweat glands to reduce perspiration, while deodorants focus on masking odor with fragrance.
Adam Mamelak, a dermatologist at Sanova Dermatology, explained in 2015 that antiperspirants work by using aluminum chloride to temporarily block sweat glands, reducing sweat production. While antiperspirants tackle both sweat and odor, deodorants only address the latter. This means those who sweat less may not need aluminum-based products, which can pose health risks if overused, particularly for individuals with impaired kidney function.
This might sound surprising or concerning, especially if you’ve heard claims linking excessive antiperspirant use to breast cancer. However, the American Cancer Society states these rumors lack scientific backing. The primary health risk associated with antiperspirants is for those with poor kidney function. Benjamin Chan, a physician at Penn Family Medicine in Phoenixville, Pennsylvania, notes that aluminum becomes a concern if kidney function drops to 30 percent or lower.
He elaborated on this in a 2019 article for the University of Pennsylvania medical center:
Excessive aluminum in the body can lead to bone diseases or dementia. Normally, kidneys filter out excess aluminum, but those with reduced kidney function struggle to do so efficiently. However, individuals with healthy kidneys can typically process the small amounts of aluminum absorbed through antiperspirants and cosmetics.
That said, you’re likely safe using as much antiperspirant as needed, but overusing it is simply wasteful—both for the product and your wallet.
Sweat itself is actually odorless.
While antiperspirants are designed to combat sweat, it’s not sweat alone that causes odor.
“The armpits contain both apocrine and eccrine glands,” explains New York dermatologist Rebecca Kleinerman to Mytour. “Apocrine glands produce thicker secretions, which skin bacteria break down, resulting in an unpleasant smell.”
As the Mayo Clinic elaborates, body odor occurs when bacteria on the skin interact with sweat, breaking it down into acids.
Apocrine glands are located in hairy areas like the armpits and groin. They secrete a milky fluid during times of stress, which remains odorless until it interacts with bacteria on the skin.
If you sweat more than average—like me, whose armpits drip even while sitting and working—you’ll likely benefit from an antiperspirant deodorant. Fortunately, combinations of both are widely available wherever deodorants are sold.
What’s the perfect amount to use?
There’s no universal rule for how much antiperspirant or deodorant to apply, nor is there extensive medical research defining the ideal quantity. Brands often promote their products based on their own testing, but there’s no evidence that two swipes are better than three or four.
Whether you deal with excessive sweating (medically termed hyperhidrosis) or not, Dr. Kleinerman recommends a balanced approach to deodorant use, telling Mytour:
Aluminum antiperspirants are designed to form a thin layer over the armpit area. Applying excessive amounts that clump or flake off isn’t beneficial, as it doesn’t properly interact with sweat ducts, even though the added fragrance might smell pleasant.
According to Kleinerman, standard over-the-counter antiperspirants typically last six to eight hours. For prescription-strength options, she advises, “Reapply every 24-48 hours until sweat control improves, then use a few times weekly to maintain results.”
Interestingly, there’s a scientifically supported method for maximizing antiperspirant effectiveness that might seem unusual: applying it at night.
Why is nighttime application recommended?
While it may seem strange, dermatologists widely agree that applying antiperspirant before bed is more effective than using it in the morning before your day begins.
Mytour first addressed this topic in 2014, and despite ongoing efforts, it remains a somewhat underappreciated nighttime habit.
As former Mytour staff writer Patrick Allan noted at the time:
Nighttime is ideal for applying antiperspirant because sweat glands are less active, and the skin is drier. The ingredients typically remain effective for about 24 hours, even after morning showers, as the pores stay blocked. If you haven’t already, consider adjusting your routine to include antiperspirant before bed. For guidance on choosing the right deodorant, check out our recommendations
here
.
Kleinerman supports this approach, explaining that aluminum antiperspirants function by “blocking or interfering with eccrine duct secretions, making nighttime application the most effective.”
Are there other ways to manage excessive sweating?
If you’ve tried every sweat-reducing method without success, you might consider Botox injections for your armpits. While effective, the results are only temporary.
Kleinerman explains to Mytour:
Botox injections are highly effective for treating axillary hyperhidrosis. They block nerves from releasing a neurotransmitter that triggers sweat production in eccrine glands. The effects typically last around three months before wearing off.
For more unconventional approaches, like using rubbing alcohol to reduce sweat, Kleinerman notes it “may temporarily reduce skin bacteria that cause bromhidrosis (body odor),” but it’s not a long-term solution for excessive sweating.
The key takeaway is to find what works best for your needs. If prescription antiperspirants or multiple Botox sessions per year aren’t for you, try applying antiperspirant at night and managing any remaining sweat as needed.
