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Topical Treatments: Aluminum chloride
Mechanism of action
Treating axillary sweating
Treating palmar sweating
Side effects
Available forms
Recommended regimen
Using occlusion and alternative vehicles
Mechanism of action
Aluminum salt solutions are the most common
antiperspirants in use today.[58]
Aluminum chloride is the partially neutralized form used
in cosmetic antiperspirants, while aluminum chloride hexahydrate
is among the most effective antiperspirants currently available.[58]
Several studies have shown that aluminum salts cause an
obstruction of the distal sweat gland ducts.[59]
A mechanism underlying this obstruction has been proposed:
the metal ions precipitate with mucopolysaccharides, damaging
epithelial cells along the lumen of the duct and forming
a plug that blocks sweat output.[58]
Sweat is still produced, as evidenced by the appearance
of miliaria (prickly heat) during heat stress, with sweat
building up behind the obstruction created by the metallic
salt.[59]
Normal sweat gland function returns with epidermal renewal,
however, necessitating retreatment once or twice a week.[58]
Long-term histologic studies of eccrine glands
in patients on chronic aluminum salt treatment have shown
destruction of secretory cells, accounting for the clinical
finding of reduced severity of hyperhidrosis, as reflected
by the need for less-frequent treatments.[59]
Other metallic salts such as zirconium, vanadium, and indium
are thought to work by the same mechanism.[58]
Some of these salts are more effective than aluminum salts,
but aluminum salts have been used for over 80 years, are
inexpensive and nontoxic, and remain the common active
ingredient of most preparations.[58]
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Treating axillary sweating
Aluminum chloride therapy, mostly effective
for axillary hyperhidrosis, was first described in 1916.[23]
Scholes and colleagues treated 65 patients with 20% aluminum
chloride hexahydrate in absolute alcohol and found that
64 of the patients reported excellent control of axillary sweating.[126]
A double-blind placebo trial of 20% aluminum chloride hexahydrate
in patients waiting for surgery showed 24 of 38 to be improved,
of which 19 decided against surgery.[109]
In a study involving 691 patients with axillary
hyperhidrosis treated with aluminum chloride, 82% of the
group reported dryness or a tolerable amount of sweating,
and, over longer follow-up, 87% reported satisfaction with
the treatment.[58]
In that study, various concentrations were evaluated, and
the authors concluded that 15% was as effective as 20% and
was better tolerated.
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Treating palmar sweating
Palmar hyperhidrosis is less responsive to
aluminum chloride therapy,[148]
and successful treatment may require concentrations up to
30%.[145] An evaporimeter was used in 12 patients with palmar hyperhidrosis to measure skin water vapor loss after treatment
with 20% aluminum chloride; the water loss was reduced by
17% at one week and by 30% at four weeks, compared to the untreated
palms. The effect was noted 48 hours after starting treatment,
and sweating increased again 48 hours after stopping treatment.[44]
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Side effects
There are individual case reports and small series of patients with facial hyperhidrosis or gustatory
sweating (Frey’s syndrome) who had a clinical response
to aluminum chloride treatment.[17,119,146]
The most common adverse effects of aluminum chloride treatment
are itching and stinging immediately after application and
ongoing skin irritation.[58] In one series of 691 patients,
pruritus was slight and short in duration in 70%, moderate
in 21%, and severe in 9%, while skin irritation was moderate
in 36% and severe in 14%. During maintenance treatment,
less itching and skin irritation were seen.[58] Damage to
fabrics also occurs, so expensive nightwear should be avoided.[145]
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Available forms
Available by prescription, 20% aluminum hexahydrate
in anhydrous ethanol (Drysol, Person and Covey, Inc., Glendale,
California) is a commonly used agent.[134]
Concentrations of 10% to 15% and up to 30% are used in compounded
formulations to treat axillary and palmoplantar hyperhidrosis,
respectively.[145]
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Recommended regimen
Following a recommended regimen may enhance
efficacy and reduce the incidence of adverse effects.[148]
Aluminum chloride should remain on the skin for 6 to 8 hours
to be effective. Overnight application is done to take advantage
of low sweat output during sleep; diffusion of the aluminum
ions into the sweat gland may be impossible if the gland
is actively excreting sweat.[58]
If the patient regularly shaves the axillary region, it
is best to wait 24 to 48 hours after shaving before applying
the medication to decrease irritation.[148]
Irritating hydrochloric acid forms in the presence of water,
so prewashing is not advised; drying the axillae with a blow
dryer may reduce irritation. [148]
In the morning, the medication should be washed off before
daytime sweating begins.[148]
Irritated skin can be treated with topical HC cream for
up to two weeks if irritation persists.[134]
If irritation persists beyond that point, a dermatology
consult should be obtained. Nightly treatments are recommended
until an effect is noted, and then the interval between treatments
can be lengthened.[134]
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Using occlusion and alternative vehicles
Other approaches to aluminum chloride therapy
include the addition of occlusion, with plastic wrap in the
axillae and on the feet and vinyl gloves on the hands. This is recommended
if the above regimen is not effective.[148]
However, another study showed that plastic film occlusion
over the aluminum-salt-treated area was not necessary.[23]
Changing the vehicle could also enhance efficacy
or reduce irritation. Although many recommend absolute alcohol
as the best vehicle for minimizing irritation, a large series
of patients followed for as long as a decade has shown that
an aqueous vehicle thickened with methylcellulose to create
a gel was the most effective formulation.[58]
In a double-blind trial in 30 patients with axillary hyperhidrosis,
triethanolamine was applied after aluminum chloride treatment
to neutralize the irritating hydrochloric acid formed.[41]
Although there was a statistically significant reduction
in skin irritation, sweat reduction dropped from 75% with
aluminum chloride alone to 55% with the combination treatment.
In a more recent study, 4% salicylic acid in a hydroalcoholic
gel base was used as the vehicle for aluminum chloride hexahydrate
in 238 patients with hyperhidrosis involving the axillae,
feet, hands, and groin.[14]
The reasons for using this combination included possible
enhancement of aluminum chloride absorption by salicylic
acid, possible additional antiperspirant effects of salicylic
acid, and potentially less skin irritation afforded by the
hydroalcoholic gel. The percentage of aluminum chloride
varied with the site treated—10% to 25% for the axillae and
30% to 40% for the palms and soles. For patients with axillary
disease, 94% reported excellent-to-good results. Excellent-to-good results were reported by 60% and 84% of patients
with palmar or plantar involvement, respectively. Patients
who had previously failed to respond to aluminum chloride
in absolute alcohol or could not tolerate it seemed to improve
with use of the salicylic acid gel vehicle. The researchers
were unable to do a double-blind comparison, as the two topical
applications had different consistencies. The researchers also suggest
further study using more-objective outcome measures.
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