Topical antiperspirants will normally have already been tried. The most effective of these which may have not been tried are the aluminium-containing compounds. Aluminium salts are present in many over-the-counter antiperspirants, typically at concentrations of 1% to 2%. However prescribed medications may contain aluminum chloride at a much higher concentration of up to 15% to 25%. It is not fully understood how they work, but it is assumed that the aluminum ions in some way block the sweat gland ducts and then after a time lead to atrophy of the secretory cells. Thus, if application is repeated on a regular basis, the effect is markedly enhanced. Therefore more severe cases of axillary or acral hyperhidrosis can be treated with Drysol (20% aluminium chloride hexahydrate dissolved in anhydrous ethyl alcohol), applied to dry skin every night and washed off in the morning, decreasing frequency of application to once per week once if sweating is brought under control.
With aluminum compounds effectiveness may be improved by covering the treated area with for example a shower cap (for scalp application), plastic wrap, and gloves or socks for hands or feet or T-shirt for axilla.
Problems include skin irritation and burning pain. To minimize irritation, it is best to wash off the aluminium preparations if used at high strength. They may help some people with palmar hyperhidrosis, but the effect usually wears off within 48 hours.
The skin should be dry before application of aluminum preparations to prevent irritating hydrochloric acid formation if moisture is present. Washing should therefore be avoided before application. Applying just before bedtime is optimum because of the relative inactivity of sweat glands through the night. Hydrocortisone creams may be applied to help with any minor irritation that may develop.
Astringent substances such as formaldehyde, tannic acid or glyceraldehyde are occasionally used to try and dry the skin, but skin irritation and allergic reactions are common and they may stain and sensitise the skin.