Excessive sweating of the feet is a very common ailment affecting around 20% of the population.

HYPERHIDROSIS = sweaty feet, i.e. excessive production of sweat by the eccrine sweat glands.

In research settings, the term "hyperhidrosis" is used when sweat secretion exceeds 100 mg of sweat per cm2 and minute. In clinical practice, however, the definition is more subjective and implies a degree of sweating that causes discomfort in the individual.

The main function of the sweat glands is to cool the body when the body temperature rises by producing sweat that evaporates on the skin surface. Evaporation is a process that consumes much energy, and the required energy (heat energy) is extracted from our body. The body temperature is regulated by the autonomous (or vegetative) nervous system, more specifically by a part of it, the Sympathetic Nervous System (SNS). When the temperature in our body rises and temperature receptors deliver this information to the SNS, it starts sending nervous signals to the sweat glands, resulting in output of sweat. Conversely, it reduces or stops the signal flow as soon as the temperature approaches the normal level. In some individuals, depending on genetical and constitutional factors, this mechanism may not be well tuned, resulting in an exaggerated response (heavy sweating) to a given need.

However, compared to other regions of the body (e.g. head and trunc), sweating of the palms and soles contributes only marginally to temperature regulation, but is necessary to create friction and improve the grip. Obviously, hyperhidrosis nullifies this physiological function and makes hands and feet slippery.

The sweat production is not constant but varies during the 24 hours, reaching minimum levels during night time and peaking during exercise, psychological or psychophysical stress, heat exposure etc.

Another factor determining the level of humidity of the skin is the capacity to evaporate, markedly reduced in humid climatic environment or when wearing closed shoes; other factors are the type of material of the shoes, the absorption capacity of the socks, etc.

BROMHIDROSIS = sweat with unpleasant odor.

Bromhidrosis is often associated with hyperhidrosis, but excessive sweating is not necessarily causing unpleasant odor. On the contrary, the sweat itself is an odorless liquid when it is expelled from the sweat glands.

The odor is caused by organic substances, splitted by microorganisms which colonize the skin surface and the material of socks and shoes. The molecules produced by such biochemical processes, mostly derivates of butyric acid, are dissolved in sweat and emit the characteristic odor of sweaty feet when evaporating. The sweat itself contributes to the creation of an environment in which the microorganisms thrive and proliferate and represents the vehicle for maleodorous substances. Moreover, even in absence of bacteria and fungi, an unpleasant odor may be emanated from the shoes when traces of organic substances contained in the leather are dissolved in the sweat.

Generally, however, it is the contamination with microorganisms in a humid microclimate which constitutes the ideal environment for developing so called foetor pedis.

Excessive foot sweat leads to several problems:

• macerated skin (increased vulnerability)
• mycosis (growth of fungi)
• early wear of shoes (often a pair of shoes is worn down after just a few weeks)
• difficulties in wearing certain types of footwear (e.g. sandals)

In addition, psychosocial discomfort (professional life, social and even familiar relationsships) is common when bromhidrosis is associated with hyperhidrosis.

Without doubt, plantar hyperhidrosis may have a negative impact on the quality of life of many individuals and may be really debilitating in some.

Often measures aimed at reducing the activity of the sweat glands are not sufficient, but have to be combined with desinfection of the skin and the footware if bromhidrosis is the main problem.

Treatment of plantar bromhidrosis

• wash the feet with desinfecting soap (e.g. detergents used by the surgeon to wash his hands prior to surgery);
• after rinsing, rub the feet with an alcoholic solution with high desinfecting potential, preferably containing rehumidifying components, like those used in surgery and available in pharmacies;
• treat mycosis (fungal disease) if present (consult a dermatologist);
• disinfect shoes and socks regularly with a proper disinfecting spray, change socks frequently;
• treatment of hyperhidrosis (see below)

Treatment of plantar hyperhidrosis

• Antiperspirants containing aluminum chloride (20-25%)
• Iontophoresis
• Surgery (Lumbar Sympathectomy)

Botulinum toxin is not recommended for treating sweaty feet: the treatment is painful and expensive and the effect inconsistent and of short duration.