Treating Hyperhidrosis: Topical Treatments

Metal Salt Based Antiperspirants

Aluminum salt solutions are the most common antiperspirants in use today. Aluminum chloride is the partially neutralized form that is used in cosmetic antiperspirants, while aluminum chloride hexahydrate is the widely used effective antiperspirant and is available in products such as Hydrosal® Gel or Drysol®.

Hydrosal® Gel is a proprietary formula combining highly effective aluminum chloride hexahydrate in a proprietary gel base.

Other metallic salts such as zirconium, vanadium, and indium are thought to work by the same mechanism as Hydrosal® or Drysol®. Some of these salts are more effective than aluminum salts, but aluminum salts have been in use for more 80 years, are inexpensive and nontoxic, and remain the common active ingredient of most preparations.

Mechanism of Action

Studies have shown that aluminum salts cause an obstruction of the sweat gland ducts at the skin's surface. It seems that the metal ions combine with proteins, damaging cells along the wall of the duct and forming a plug that blocks sweat output. Sweat is still produced, and may appear as prickly heat ("miliaria") during heat stress, with sweat building up behind the obstruction created by the metallic salt.

The effects of these products are not permanent and they must be applied on a regular basis to maintain the therapeutic effect.

This is the most commonly used, first line treatment for hyperhidrosis of the underarms, hands and feet. It is not suitable for treatment of the face and scalp due to irritation to the eyes.

Effectiveness:

• Concentration dependent (20% or above needed)
• pH dependent (the more acid the better, but lower pH also more is more irritating to the skin)
• Minimally to moderately effective

Side effects:

• Itching,
• Stinging,
• Erythema or reddening of the skin,
• Other irritation

• Miliaria or heat rash is very rare

• C$20-30 per bottle, can cost hundreds per year

Acids and Aldehydes:

These products work by denaturing or breaking down proteins, thus temporarily closing the sweat gland ducts. They have a short lasting effect. Aldehydes are used to treat the palms and soles and are not as effective in the axillae.
Formaldehyde has been used but Glutaraldehyde is more effective, especially for the feet, however this product stains the skin. These agents are applied to the affected areas three times a week for two weeks, then once a week, as necessary.

Other Topical Agents

In the past, topical agents such as boric acid, 2% to 5% tannic acid solutions, resorcinol and potassium permanganate have been used with minimal efficiency.

Local anesthetics:

Topical application of local anesthetics can block the nerve conduction and reduce sweating, but they are not widely used nor are they highly effective. Continued use of these agents can also cause contact hypersensitivity.

Anticholinergics

These medicines block the action of acetylcholine on the nerves and stop the message that stimulates excessive sweating.
Usually tablets of the anticholinergics are dissolved in a 20% alcohol or a water-based solution of aluminum chloride hexahydrate and applied to the skin once or twice a day. This therapy is not commonly used but may be a useful addition to iontophoresis.