BOSTON – Aluminum chloride, a chemical found in rocks and as ancient as the earth itself, still can control hyperhidrosis for many people when used correctly. It is the active ingredient in over-the-counter antiperspirants as well as prescription products.
At the American Academy of Dermatology summer meeting, Louis Kuchnir, MD, who is a physical chemist by training as well as a dermatologist, described the chemical properties of aluminum chloride and how it works, based on those properties.
Just as no dermatologist would prescribe isotretinoin for acne without understanding its mechanism of action, so should physicians know how aluminum chloride works to be able to use it effectively, he said. Each aluminum chloride molecule can covalently bind six water molecules and tightly bind another shell or two of 12-20 molecules, with a further third shell, all “making the water very viscous such that the weak muscles that push sweat out of our sweat glands are unable to move the sweat to the surface of our skin,” he said.
“When aluminum chloride gets close to water, it soaks it up and thickens it,” said Dr. Kuchnir, who is in private practice in Marlborough, Mass. “By spreading it over the areas that perspire, it thickens the water in the top of the duct where the sweat’s coming out, and that thickening, like a gel, will block it.” Most people get satisfactory results for a full day from one application of an antiperspirant containing aluminum chloride. A failure to control sweating results from such excessive sweat gland activity that the moisture pushes the gel away from the top of the sweat gland.
Diagnosis of hyperhidrosis
A diagnosis of primary hyperhidrosis requires focal, visible sweating present for at least 6 months with no apparent secondary causes and at least two of the following criteria:
• It is bilateral and symmetric.
• It impairs activities of daily life.
• There is at least one episode per week.
• The age of onset is less than 25 years.
• There is a positive family history.
• There is cessation during sleep.
Patients whose sweating is not controlled with regular antiperspirant deodorants may find relief using an aluminum chloride–containing liquid that is not a classic deodorant. These products are available over the counter. Beyond that, primary care doctors often prescribe a 20% aluminum chloride liquid, which can be very effective.
If a patient still has hyperhidrosis, often of the axillae or the palms of the hand, a dermatologist may recommend injections of botulinum toxin A “to disable sweat glands up to 10 months at a time ... which is a costly procedure that has been heavily marketed over the past 5-10 years,” Dr. Kuchnir said. By asking patients what they have been using and what the problem is, and understanding why aluminum chloride failed them in the past, he has found that he could get “four out of five of these patients to be happy and not perspiring with topical antiperspirants, often prescription strength, even though virtually all of them are ready to go for neurotoxins when I first meet them.” The remaining 20% will need botulinum toxin A to block nerve endings from communicating with the smooth muscle in the eccrine gland, which is required to push sweat out of the gland.
Botulinum toxin for hyperhidrosis is covered by prescription drug benefit plans, and prior authorization is routine. Patients should obtain the drug at the best price they can find and then bring it to the physician for injection. The duration of action is often 8-10 months, so dosing can be done yearly in the springtime. Aluminum chloride preparations can be retried once botulinum toxin wears off.
Countering common problems with aluminum chloride preparations
The two most common complaints about topical aluminum chloride preparations are that they sting or do not work. Stinging is often from alcohol in the liquids, so letting it evaporate from the armpits before patients put their arms down can solve this problem. As for the problem of not controlling sweating, Dr. Kuchnir said the most common reason is that patients apply the products while they are actively sweating, “so the aluminum chloride doesn’t have time to gel in the eccrine gland.” Another reason is that the preparation has too much moisture in it and will fail to block sweating.
To be able to apply an antiperspirant to dry skin, patients should minimize the causes of sweating by being in a cool, calm environment. The temporary use of anticholinergic drugs may help. Once control of sweating is achieved, the aluminum chloride–containing preparation should be reapplied before it wears off.