The cause of primary (focal) hyperhidrosis is not known. However, secondary hyperhidrosis can have numerous causes. Depending on the type of hyperhidrosis, causes can range from emotions (e.g., stress) to a serious underlying medical disorder (e.g., heart disease, tuberculosis). One of the more common causes includes heredity. Individuals who are genetically predisposed to hyperhidrosis often have sweaty palms and feet.

Spicy foods and hot beverages, and those containing caffeine and alcohol, can also trigger hyperhidrosis, as can some types of drugs (e.g., certain antipsychotic medications). Hyperhidrosis can also result from overdose of an analgesic (e.g., aspirin, acetaminophen) or hormonal factors, such as hot flashes caused by menopause, or reduced levels of the male hormone testosterone (in men).   

Other potential causes of hyperhidrosis include:

• Excessive heat
• Hypoglycemia (low blood sugar)
• Exercise
• Fever
• Toxins (e.g., arsenic, drug or alcohol addiction)
• Spinal cord injuries
• Injury or disease of the parotid (salivary) gland
• Metabolic disorders (e.g., diabetes, hyperthyroidism)
• Infection (e.g., tuberculosis)
• Disease (e.g., malaria, certain cancers)
• Disorders of the central nervous system (e.g., encephalitis)

In addition, a small amount of individuals have an abnormal number and/or distribution of eccrine sweat glands. In some instances, this rare occurrence may be responsible for causing hyperhidrosis.