How common is hyperhidrosis, or excessive sweating?
Do you seem to have more armpit sweat than others? In my experience, hyperhidrosis is more common than we used to think in dermatology. Published medical studies estimating a low prevalence are, “outdated and underestimate,” according to a more recent medical study.(1)
This same study estimates the incidence in the U.S. at approximately 5%. According to another study done in both China and Canada, the incidence was found to be slightly over 15%! Other sources cite the incidence as much less.
Both genders are affected, and there is significant ethnic variation in the incidence of hyperhidrosis. For example, it is 20 times more frequent in the Japanese than other ethnic groups.
Sources cite armpit (axillary) hyperhidrosis as occurring in approximately 5% of the population.
The term hyperhidrosis involves more than armpit sweating, though. The excess sweating can involve either axillary skin (armpits), palms or facial skin, or it can be generalized. Hyperhidrosis usually starts before the age of 30. When hyperhidrosis develops after the age of 30, it is called Late Onset Hyperhidrosis.
Hyperhidrosis may run in families, and one of the genes for inheriting it has been identified.(5) Interestingly, hyperhidrosis is not a problem patients come in asking for help with in my clinical experience. It is usually brought up as a secondary question that a patient asks me during the course of a visit scheduled for a different skin problem.
At what point should someone see their doctor for excessive armpit sweat?
The diagnosis of hyperhidrosis is made if a person has excessive sweating for over six months without an obvious cause AND the sweating has two or more of the following characteristics:
- It impairs daily activities.
- It occurs symmetrically on both sides of the body (like both armpits) at least once per week.
- It begins before age 25, stops when you are asleep, or you have a family history of the same thing.
You can also have hyperhidrosis due to medicines, illnesses etc. But, this type is called Secondary Hyperhidrosis. And treatment would be aimed at the condition causing the sweating, not at the sweat glands and ducts, which are the target with treatment for hyperhidrosis.
How do anti-perspirants work to control sweat in hyperhidrosis?
Anti-perspirants work by blocking the sweat duct. The active ingredients are metallic aluminum salts. The original aluminum salts were either aluminum chloride or aluminum chlorhydroxide.
These ingredients can be irritating to skin, especially in higher concentrations. Another, less irritating, aluminum salt is aluminum zirconium tetrachlorohydrex glycine (meaning the aluminum is coupled with zirconium instead of chloride).
Aluminum salts do not stop sweat production; sweat is still produced from the gland, but it can’t exit through the duct to the skin. The blockage is temporary which is why anti-perspirants need to be reapplied either daily or weekly depending on the type of product.
Do the different anti-perspirants have different concentrations of active ingredients?
Anti-perspirants are regulated strictly by the FDA as drugs (3). There are 18 different aluminum salts allowed to claim anti-perspirant effectiveness. Some are more commonly found in commercial anti-perspirants than others including: aluminum chloride, aluminum chlorhydroxide and aluminum zirconium tetrachlorohydrex glycine.
The maximal percent allowed by the FDA for each of the 18 salt varies according to FDA regulations. In general, concentration ranges for non-prescription products run from 15 to 25%. These active ingredients are combined with other ingredients to create a final product, and it is the overall formulation that determines effectiveness and/or skin irritation.
The FDA also strictly regulates the claims that an anti-perspirant can make, and these must be substantiated by testing.
Products that have demonstrated standard effectiveness will provide a 20% reduction in sweat over 24 hours. You will see them labeled with statements such as “all day protection,” “lasts 24 hours,” etc. If 30% reduction of sweat over 24 hours has been demonstrated, then a claim of “extra effective” can be made.
Interestingly, when you go anti-perspirant shopping, you are more likely to see products labeled as “clinical strength,” and I do not see a strict definition for this in the FDA regulations. When I read the ingredients listed on these products, I find that within an anti-perspirant brand, this term is usually reserved for their products with higher concentrations of their chosen active aluminum salt(s).
Here are some examples:
- Regular anti-perspirants:
An example is Secret Original Solid which contains 15% aluminum zirconium tetrachlorohydrex gly. Dove’s Cool Care Essentials Anti-perspirant contains 15.2% aluminum zirconium tetrachlorohydrex glycine.
- “Clinical Strength” anti-perspirants:
Secret Clinical Strength Solid contains 20% aluminum zirconium tetrachlorohydrex Gly, Dove Clinical Protection contains 15 to 20% aluminum zirconium tetrachlorohydrex glycine, and Certain Dri “Prescription Strength Clinical” contains about 12% aluminum chloride and is available without a prescription.
- Prescription Anti-perspirants:
Commercial made products are made by the company Person and Covey. They are aluminum chloride solutions formulated in anhydrous alcohol, which increases effectiveness while minimizing irritation.
That said, I have prescribed these for years and tried them myself. They can be quite irritating. Drysol is the strongest, commercially-available prescription anti-perspirant and contains 20% aluminum chloride.
Other prescription anti-perspirants in the 10-30% range can be prescribed by your doctor but are not premade commercial products. They must be made individually for you by specialized pharmacies (called compounding pharmacies). This practice is becoming rare.
Drysol and prescription anti-perspirants are used differently than non-prescription products. They are to be applied to the affected area nightly for a week or so until sweat is reduced (meaning the ducts are blocked). After that, the solution is often applied only once or twice a week. The solution is to be washed off six to eight hours after application. Use must be postponed if irritation develops.
Another milder prescription anti-perspirant made by Person and Covey is Xerac AC, which contains 6.25% aluminum chloride. This sounds low, but even at this concentration, it is effective and available only by prescription. It is less irritating than Drysol or custom, higher-concentration products and is often the first prescription product that your doctor may recommend.
Is Botox only for people with hyperhidrosis, or can people who are just really sweaty use it, too?
Botox reduces sweat production in general, regardless of whether it is excessive. It is only FDA-approved for use in people suffering from hyperhidrosis. However, Botox can reduce sweat from baseline production to as little as 25 or even as low as 10% (4). Reduction in sweat can last from 3 to 9 months before you need another treatment. Some people can see reduction in sweat for up to 16 months. (5)
How does Botox in the armpits help prevent/reduce excessive sweating?
Hyperhidrosis happens because the nervous system is not functioning correctly in an area of skin with a lot of sweat glands. The sweat glands are turned on by a very specific type of nerve using a signal that involves secretion of the nerve’s chemical neurotransmitter (a chemical messenger that talks specifically to nerves).
Botox blocks this neurotransmitter from turning on the sweat gland. The blockage is not permanent which is why Botox wears off, and you need additional treatment when excess sweating returns.
- James Doolittle, Patricia Walker, Thomas Mills, Jane Thurston, Hyperhidrosis: an update on prevalence and severity in the United States, Archives of Dermatological Research, December 2016, Volume 308, Issue 10, pp 743–749
- James, W. D., Berger T. G, Andrews’ Diseases of the Skin, Clinical Dermatology, 12th edition, Copyright 2016 Elsevier, Inc., Pages 771-772
- Amanda-Amrita D. Lakraj, Narges Moghimi, and Bahman Jabbari, Hyperhidrosis: Anatomy, Pathophysiology and Treatment with Emphasis on the Role of Botulinum Toxins, Toxins (Basel). 2013 Apr; 5(4): 821–840. Published online 2013 Apr 23. doi: 10.3390/toxins5040821 PMCID: PMC3705293 https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3705293/