Hyperhidrosis can be either primary (focal) or secondary, depending on its cause. Individuals are typically diagnosed with primary hyperhidrosis when the disorder is localized (confined to the armpits, hands and feet), and no underlying medical condition can be identified. Secondary hyperhidrosis is diagnosed when excessive sweating occurs in response to a separate medical condition (e.g., hyperthyroidism, hypoglycemia) or other factors (e.g., spicy foods, drugs, stress).

Hyperhidrosis can be further classified according to its cause. For instance, excessive sweating can be caused by the hypothalamus region of the brain, which regulates the body’s temperature. This form is called hypothalamic hyperhidrosis, and can be triggered by numerous factors (e.g., physical exertion, underlying medical conditions, drugs).

Location can be used to classify hyperhidrosis as well. For instance, excessive sweating in the hands is known as palmar hyperhydrosis, excessive sweating in the underarms is known as axillary hyperhidrosis and excessive sweating in the face and/or feet is known as plantar hyperhidrosis.

Hyperhidrosis can also be emotionally induced. This form is known medically as cortical hyperhidrosis because it is related to the emotional, mental and sensory processes of the cerebral cortex region of the brain. Cortical hyperhidrosis is one of the most common types of excessive sweating. It affects the palms, soles and armpits. In most cases, sweating in the armpits diminishes or stops during sleep and increases during more concentrated emotional, mental or sensory stimulation.

Hyperhidrosis may affect the following parts of the body:

• Taste buds. Hyperhidrosis may result from eating spicy foods or drinking certain beverages (e.g., alcohol). It may also occur in response to injury or disease of the parotid gland (a type of salivary gland), or in relation to some disorders of the central nervous system (e.g., encephalitis). Hyperhidrosis caused by the consumption of spicy foods most commonly affects children and young adults in warm environments. Sweat typically appears shortly after consumption either above the upper lip or on the cheeks. The duration of sweating may be brief or last as long as the food is in the body.
  
  
• Spinal cord. Hyperhidrosis may occur as a result of any injury or disease process that severs the spinal cord or otherwise interferes with proper functioning of spinal neurons. Hyperhidrosis in this region often appears suddenly and may last indefinitely. Spinal sweating appears below the level where the spinal cord was severed or interrupted.

Another type of hyperhidrosis called compensatory hyperhidrosis occurs when the sweat glands of a certain area of the body produce excess sweat to compensate for underactive sweat glands in another bodily region. This commonly affects people with hyperhidrosis that has been successfully treated surgically or with Botox injections. Patients with obstructed sweat glands from hyperhidrosis (miliaria) may experience compensatory hyperhidrosis at an alternate location, as may diabetes patients with anhidrosis (absence of sweating).