If everytime you use the machine, you develop a stuffy nose, it is an allergic
reaction to the machine. But if it an occasional occurrence, not related to the machine, it could be due other causes like dust. In all, the primary treatment is simply avoiding the things that trigger your symptoms. In addition, the allergic symptoms are often treated with a drying nasal spray (like Atrovent) and antihistamines like chlopheneramine and lovatidine are effective.