Heat and emotions are causes of underarm sweating in healthy people, according to MedicineNet. Metabolic and neurological disorders can cause hyperhidrosis, or excessive sweating. People with auxiliary hyperhidrosis, a common disorder, experience excessive underarm perspiration almost constantly, and neither the temperature of their environment nor their emotions affect the condition.
Hyperhidrosis occurs in people who are otherwise in good health, and their underarm sweating problems typically start at the onset of puberty, notes MedicineNet. Underarm perspiration treatments include applying non-prescription antiperspirants and prescription antiperspirants that contain aluminum chloride hexahydrate and destroying sweat glands using microwaves. The U.S. Food and Drug Administration has approved botox injections to stop excessive underarm perspiration. A last resort for severe cases is cervical sympathectomy, a surgical procedure that interrupts passageways of certain nerves.