Effects of hot bath therapy on cholinergic urticaria with hypohidrosis or anhidrosis

Cholinergic urticaria with hypohidrosis or anhidrosis (CUHA) can impair quality of life due to itching, tingling, and reduced sweating. Current treatment options for CUHA include antihistamines, pulsed steroids, and sweat-promoting therapies such as exercise or hot baths. However, the efficacy of these therapies, particularly hot bath therapy, has yet to be established. We evaluated the efficacy of hot bath therapy in patients with CUHA. We enrolled eight patients who underwent hot bath therapy between January 2010 and August 2022. Patients had a half-body bath in a bathtub filled with hot water (40-43°C) for 30-60 minutes daily for 3-7 days. After treatment, pain improved in three (42.9%) patients, urticaria improved in four (50%) patients, and anhidrosis improved in five (62.5%) patients without any severe adverse events. Because hot bath therapy is easily performed, it should be considered a treatment option for patients with CUHA.