Even though absolute ethanol ( 95%) has been the traditional vehicle in which aluminum chloride hexahydrate has been dissolved for a great number of years, the fact remains that alcohol may cause an unbearable irritation in some patients. There are few reports that testify that alcohol gels are less irritating and better tolerated than alcohol solutions. Moreover, aluminum chloride in its alcoholic base does not penetrate adequately through the
thick horny layers present on the palms and soles to exert its antiperspirant effect. The role of salicylic acid in this formulation is to enhance the penetration of aluminum chloride through the thick horny layers and, having antiperspirant properties of its own, it could act synergistically with aluminum chloride to enhance the required antiperspirant effect. Occlusion with Cellophane paper becomes unnecessary with this formulation.
Aluminum salts create a plug at the end of the sweat duct (acrosyringium) near the skin surface which will induce structural changes in the axillary eccrine glands on the long run, thus diminishing the sweat flow which in its turn will diminish the need for antiperspirants.
Treatment with this formulation could be as rare as once a month. The following factors should be taken into account when prescribing aluminum chloride formulations: the age of the patient, the affected site, the severity of HH and the patient’s tolerance. The concentration of aluminum chloride should be adjusted accordingly.