Primary axillary hyperhidrosis, also known as excessive underarm sweating, is a medical condition defined by excessive, uncontrollable underarm sweating that goes well beyond what the body needs for normal temperature regulation. It is the most prevalent form of primary hyperhidrosis, affecting an estimated 15.3 million people in the United States and it typically begins in adolescence or early adulthood, often before age 25. Unlike secondary hyperhidrosis, which is caused by an underlying medical condition or medication, primary hyperhidrosis has no identifiable external cause. The condition is bilateral (affecting both underarms), tends to occur during waking hours, happens at least once a week, and frequently runs in families, with 35% to 56% of patients reporting a family history of excessive sweating.1,2
Excessive underarm sweating begins in the nervous system rather than in the sweat glands themselves. Sweat glands (eccrine glands) are responsible for producing sweat to help regulate body temperature. These glands are controlled by the nervous system, which sends signals using a chemical messenger called acetylcholine to trigger sweating. In primary hyperhidrosis, this signaling system is overactive, causing the glands to continue producing sweat even when it is not needed, such as in the absence of heat or stress. Importantly, the sweat glands themselves are normal. The condition is caused by overactive signals from the nervous system, not by a problem with the glands.
2
Despite how significantly excessive underarm sweating affects daily life, it remains widely underdiagnosed and undertreated. Research shows that excessive sweating impairs emotional well-being, social interactions, professional performance, and clothing choices, yet less than half of patients have ever discussed their symptoms with a healthcare provider. The condition is strongly associated with anxiety and depression, with studies documenting improvements in both when sweating is effectively controlled.
1,2,3,4
