09/26/2026
A Sleep Review article explained that humidification helps for upper-airway comfort.
An American Academy of Sleep Medicine systematic review found that heated humidification reduced CPAP-related side effects including dry mouth and throat, nasal congestion, dry nose, nasal discharge, and sore throat. A 2023 meta-analysis of nine randomized trials reached a similar conclusion, with significant improvement in dry nose, blocked nose, dry mouth, and dry throat.
The effect can go beyond how the airflow feels. In a randomized crossover study of 20 positive airway pressure users with symptomatic nasal obstruction, heated humidification reduced nasal resistance, lavage cytokines, inflammatory cell infiltration, and fibrosis in the nasal mucosa. For someone dealing with substantial dryness, irritation, or congestion, that is a real benefit.
The adherence evidence is much less convincing. The AASM review found no clinically significant improvement in CPAP use with humidification, and the 2023 meta-analysis also found no significant increase in adherence. That does not make comfort a minor outcome. If humidification makes therapy easier to tolerate, that is useful on its own. It simply should not be treated as an adherence intervention that reliably adds hours of use.
When Congestion Needs More Than Moisture
Congestion is a symptom that humidification can help, but the water chamber has limits. A systematic review of nasal function and CPAP use found that lower nasal resistance and larger nasal cross-sectional area were generally associated with better CPAP use, while studies of CPAP’s effect on nasal symptoms produced mixed results.
Humidity is easy to keep adjusting because the control is right there on the machine. If a patient remains significantly congested after reasonable changes, continuing to move the setting up and down tells us less and less. Rhinitis, chronic nasal obstruction, and other persistent nasal problems can interfere with therapy tolerance and deserve clinical evaluation.
