Side effects of CPAP

The normal treatment for obstructive sleep apnoea is a CPAP (continuous positive airway pressure) machine. The patient wears a mask over the face and air is applied at a pressure that exceeds the airway opening pressure, thereby enabling the patient to breathe without cessation. In simple terms, it may be best understood as a small vacuum cleaner working in reverse, applying sufficient air pressure to force the airways open.

The CPAP can resolve apneas in many patients, leading to improved sleep quality, decreased sleepiness, and lower blood pressure.1,2,3,4

The machine helps the patient as long as he or she continues to use it. On the downside, it does nothing to address the major contributory factor of sleep apnoea, namely chronic overbreathing. Wearing a mask during sleep can be claustrophobic, uncomfortable, cumbersome, and inconvenient, and getting tangled in the tube can be annoying. The air is very dry, which may cause rhinitis, a dripping nose, a blocked nose, and nasal irritation. Even when the mask is worn correctly, the feeling of the airflow is often described as putting ones head out of a car window while the car is moving at 30 miles per hour. Partners and patients often find the humming of the machine very distracting. The machine has to be cleaned on a regular basis, but few do this. Overall, while it is accepted as the gold standard of treatment, the CPAP machine has major short comings.

During one study of 300 patients referred to the London Chest Ventilatory support unit, it was found that 96% of patients complained of at least one side effect resulting from the therapy, while 45% complained of a side effect from the nasal mask.5

In a study of 80 patients, Verse et al. found that the most prevalent side effects were disturbance of the mask during the night (71.3%), dry mouth (47.5%), dry nose (46.3%), pressure marks from the mask (41.3%), crusts within the nasal cavity (38.8%), and hearing loss (26.3%). Mouth and nose dryness were considered the most irritating side effects.6

In another study of 41 patients with OSAS, the paper noted that “the most frequently reported problems were a tender region on the bridge of the nose and discomfort associated with a dry nasal mucosa. Although CPAP treatment was initially accepted by most patients, adverse effects and other difficulties decreased patient compliance, with time, in many cases.”7

A paper published in The Canadian Respiratory Journal observed that “compliance is a significant problem and has been incompletely assessed in long-term studies.” After evaluating 80 patients to determine long-term compliance with CPAPA, the authors concluded that “although many patients with OSA derive subjective benefit from, and adhere to treatment with CPAP, a significant proportion of those so diagnosed either do not initiate or eventually abandon therapy.”8

The journal Sleep found that only 40% of the 162 newly diagnosed patients who required CPAPA therapy accepted the treatment. The paper noted that compliance was higher in higher socioeconomic groups than the lower.9 Other researchers found that “failure to comply with treatment has been reported to be as high as 25 to 50%, with patients typically abandoning therapy during the first 2 to 4 weeks of treatment.”10

According to Broström A et al., “Adherence to CPAP treatment is a multifaceted problem including patient, treatment, condition, social, and healthcare related factors. Knowledge about facilitators and barriers for adherence to CPAP treatment can be used in interventional strategies.”11


  • Pepperell JC, Ramdassingh-Dow S, Crosthwaite N, et al. Ambulatory blood pressure after therapeutic and subtherapeutic nasal continuous positive airway pressure for obstructive sleep apnoea: a randomised parallel trial. Lancet. 2002;359:204-10.
  • Hack M, Davies RJ, Mullins R, et al. Randomised prospective parallel trial of therapeutic versus subtherapeutic nasal continuous positive airway pressure on simulated steering performance in patients with obstructive sleep apnoea. Thorax. 2000;55:224-31.
  • Norman D, Loredo JS, Nelesen RA, et al. Effects of continuous positive airway pressure versus supplemental oxygen on 24-hour ambulatory blood pressure. Hypertension. 2006;47:840-5.
  • Shivalkar B, Van de Heyning C, Kerremans M, et al. Obstructive sleep apnea syndrome: more insights on structural and functional cardiac alterations, and the effects of treatment with continuous positive airway pressure. J Am Coll Cardiol. 2006;47:1433-9.
  • Kalan A, Kenyon GS, Seemungal TA, Wedzicha JA. Adverse effects of nasal continuous positive airway pressure therapy in sleep apnoea syndrome. J Laryngol Otol. 1999 Oct;113(10):888-92.
  • Verse T, Lehnhardt E, Pirsig W, Junge-Hülsing B, Kroker B. [What are the side-effects of nocturnal continuous positive pressure ventilation (nCPAP) in patients with sleep apnea for the head-neck region?].[Article in German] Laryngorhinootologie. 1999 Sep;78(9):491-6.
  • Kuhl S, Hollandt JH, Siegert R. [Therapy with nasal CPAP (continuous positive airway pressure) in patients with obstructive sleep apnea syndrome (OSAS). II: Side-effects of nCPAP therapy. Effect on long-term acceptance] Laryngorhinootologie 1997 Oct;76(10):608-13.
  • Wolkove N, Baltzan M, Kamel H, Dabrusin R, Palayew M. Long-term compliance with continuous positive airway pressure in patients with obstructive sleep apnea Can Respir J. 2008 Oct;15(7):365-9.
  • Simon-Tuval T, Reuveni H, Greenberg-Dotan S, Oksenberg A, Tal A, Tarasiuk A. Low socioeconomic status is a risk factor for CPAP acceptance among adult OSAS patients requiring treatment. Sleep. 2009 Apr 1;32(4):545-52.
  • Zozula R, Rosen R Compliance with continuous positive airway pressure therapy: assessing and improving treatment outcomes. Curr Opin Pulm Med. 2001 Nov;7(6):391-8.
  • Broström A, Nilsen P, Johansson P, Ulander M, Strömberg A, Svanborg E, Fridlund B Putative facilitators and barriers for adherence to CPAP treatment in patients with obstructive sleep apnea syndrome: a qualitative content analysis. Sleep Med. 2010 Feb;11(2):126-30. Epub 2009 Dec 9.