Hyperhidrosis is defined as excessive sweat production over the entire body surface or only in certain areas (scalp, palms of the hands, soles of the feet). The skin is constantly damp and cold. The scalp, due to the presence of hair, may on the contrary be warm

We must distinguish temporary hyperhidrosis due to physical hyperactivity, febrile states, sauna, vomiting or dysentery, from chronic hyperhidrosis due to particular conditions and diseases of internal organs such as:

• hyperthyroidism,
• hypoglycaemia
• alcoholism
• psychological conditions of anxiety, fear, shyness, insecurity.

Other causes of hyperhidrosis include:

• hyperemia: overheating of the body that accelerates blood circulation and increases perspiration. It may depend on climatic, emotional or pharmacological conditions;
• the lymphatic circulation: a slowing of the lymphatic circulation leads to an accumulation of lymph at the subcutaneous level with stagnation and transpiration of liquids;
• the menopause: the hormonal imbalances that occur also cause skin vasodilation accompanied by hypersweating.

This is also evident in particularly psychologically sensitive people who suffer from shyness, fear, uncertainty.

People who feel inadequate in every situation and live their working, social and private lives in a condition of intense discomfort and psycho-emotional tension.

Very often hyperhidrosis of the scalp is confused with seborrhoea but there are elements that differentiate the two scalp anomalies:

• Hyperhidrosis sufferers have skin with a whitish appearance, little or no redness, sweaty, not shiny,
• hair looks dull and limp with dry ends,
• the skin on the face is neither oily nor greasy.

Cause of hyperhidrosis are the eccrine sweat glands, located all over the body, especially on the scalp as well as on the face, palms of the hands, soles of the feet, inguinal region and submaxillary region.

The sweat glands have a tubular structure, with the basal part localised at the level of the deep dermis and hypodermis, gathered like a ball on itself.

These glands flow on the epidermal surface at an epidermal ridge, are highly vascularised and innervated, and are regulated by the autonomic nervous system.

The product of the sweat glands is sweat, 98-99% of which consists of water, 0.8-1% of mineral salts and the rest of organic substances such as urea, lactic acid, uric acid, ammonia, etc. Sweat, combining on the surface with sebum, determines the formation of the ido-acid-lipid film.

The increase of the sudorific component in the composition of the hydrolipidic film leads to an increase of the pH towards alkaline values with loss of bacteriostatic power and sensitisation of the scalp, which is why it is essential to cleanse hyperhidrotic skin frequently and with shampoos with an acid pH (4.5 - 5.5) for frequent use.