A Review of the Etiologies and Key Clinical Features of Secondary Hyperhidrosis.

Secondary hyperhidrosis is a multifactorial condition that poses unique diagnostic and management challenges. Distinguishing secondary from primary hyperhidrosis remains difficult due to overlapping symptoms. This review consolidates existing evidence on the numerous underlying causes and pathophysiologic mechanisms of secondary hyperhidrosis across various disciplines. Secondary hyperhidrosis typically manifests in the fourth decade of life or later, whereas primary hyperhidrosis usually begins earlier. Generalized hyperhidrosis often suggests a secondary cause, though the distribution can vary, including focal symmetric/asymmetric or regional patterns depending on the underlying condition. Key clinical features such as lack of family history and associated symptoms provide additional clues favoring a secondary etiology. Recognizing these distinct characteristics is crucial for accurate differentiation between secondary and primary hyperhidrosis, thereby guiding appropriate evaluation and management of the underlying cause.