Dermatology Made Easy is based on the most popular topics from DermNet NZ's vast array of material. The book combines the essential focus of the ‘Made Easy’ book series with the authority and knowledge base of DermNet NZ's unparalleled resources.
Author: Vanessa Ngan, Staff Writer, 2005.
An antiperspirant is a chemical agent that reduces perspiration or sweating. The active ingredients of roll-on and spray formulations are traditionally the metallic salts aluminium chloride and aluminium chlorohydrate. These are formulated into preparations of varying strengths. More concentrated solutions are used to control excessive sweating (hyperhidrosis).
Newer generation antiperspirants contain aluminium zirconium compounds. These are better tolerated by the skin and are less likely to cause irritation or aggravation to razor burn.
Diphemanil methylsulfate powder may also be used to reduce perspiration. It is particularly useful on an amputation stump to reduce irritation by a prosthesis.
Deodorants are not antiperspirants. Deodorants do not prevent sweating. Their aim is to mask the smell produced by sweat-eating bacteria. An antiperspirant preparation may contain a deodorant.
Aluminium-based antiperspirants work by blocking the sweat ducts, thereby reducing the amount of sweat that reaches the skin’s surface. Aluminium salts are soluble as long as the formulation is acidic (low pH). When they are applied to skin and come in contact with sweat, the pH rises causing the aluminium salts to precipitate out and form a plug over the sweat glands. Sweat continues to be produced by the sweat gland but it just isn't able to reach the surface of the skin.
Diphemanil methylsulfate is a drug that opposes the action of the parasympathetic nerves that control sweat production.
A higher concentration antiperspirants is usually more effective than a low concentration or aluminium-free preparation. However, increasing the strength can also increase the potential for side effects. A couple of simple rules apply to their use.
Antiperspirants are often the first-line of treatment for underarm hyperhidrosis as they are readily available from the pharmacy or supermarket. Antiperspirants may also be used in other sites of the body that tend to sweat excessively. If standard preparations fail, stronger strength preparations are available at your pharmacy.
Sweat is a dilute salt solution produced by eccrine sweat glands spontaneously or in response to heat, exercise and stressful events. Eccrine sweat is initially odourless but can start to smell if bacteria get a chance to break down the stale sweat. The eccrine glands are distributed over the entire body but are most numerous under the arms and on the palms and soles.
Apocrine sweat glands are located under the arms, around the breasts and in the groin. After puberty, they produce a thick secretion that contains pheromones, the “personal scent” that most people find unpleasant. In addition, bacteria that normally live on the skin break down apocrine sweat and this produces offensive body odour. Body odour is worse if there are more bacteria present or the level of apocrine sweat production is high. Antiperspirants also help to reduce apocrine sweat production.
Avoid applying antiperspirants to mucous membranes (mouth, nose, eyelids, genitals, anus).
Antiperspirants may cause irritant or allergic contact dermatitis. This may be from the active ingredient or diluents in the preparation. The skin around the underarm area is particularly prone to develop these reactions because it is thin, delicate, moist and occluded.
People at risk of developing a reaction to an antiperspirant include those with:
To reduce the possibility of reactions less concentrated preparations should be used in susceptible groups.
In rare cases, where a hair follicle is blocked over a long period of time, a cyst may develop. Infected cysts damage the ducts and form painful hard lumps that may need to be surgically removed.
Use of diphemanil methylsulfate on the face may lead to dry mouth and other “muscarinic” (anticholinergic) side effects. It should not be used in young babies as it has been reported to cause toxicity.
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