What are the common side effects of CPAP (continuous positive airway pressure) therapy?

CPAP Side Effects

The most common side effects of CPAP therapy include dry mouth/throat (36-65%), nasal congestion (25-27%), mask-related problems (air leaks, skin irritation, pressure marks), and increased awakenings, though most are minor, reversible, and can be effectively mitigated with proper interventions. 1, 2, 3

Most Frequent Side Effects

Nasal and Oral Symptoms

• Dry mouth or throat affects 36-65% of patients and is the most commonly reported side effect 2, 4, 3
• Nasal congestion occurs in 25-27% of users 2, 4
• Dry nose, rhinorrhea (nasal drip), and sneezing affect over 35% of patients 3
• These upper airway complaints are often present even before CPAP initiation and may worsen after the first treatment night, particularly in patients with milder OSA (AHI <20) 5

Mask-Related Problems

• Air leaks from the mask are among the most common complaints 2
• Skin irritation, abrasions of the nasal bridge, and facial pressure marks occur in approximately 50% of patients 3
• Red eyes in the morning affect 9-24% of users, with higher rates in those using standard silicone masks versus individually molded masks 3
• Allergic reactions to mask materials occur in 5-13% of patients 3

Sleep Disruption

• Increased number of awakenings affects a significant proportion of users and is associated with treatment dropout and reduced adherence 2
• Sleep disruption is reported by 11% of patients 4

Gastrointestinal Effects

• Aerophagia (air swallowing) is a recognized side effect that can cause gastric distension, bloating, and belching 6
• Patients with aerophagia symptoms have a significantly higher prevalence of gastroesophageal reflux symptoms (29% vs 10%) and nighttime reflux (9% vs 2%) compared to those without aerophagia 6

Ear-Related Symptoms

• Ear pain (otalgia) occurs when positive airway pressure is transmitted through the Eustachian tube into the middle ear, potentially causing tympanic membrane displacement 7

Other Side Effects

• Sinus pain and headaches occur in some patients 1
• Hoarse voice, sore throat, and reduced sense of smell are reported 1
• Nosebleeds can occur 1
• Equipment noise bothers 9% of patients, particularly those with mild OSA 4, 3

Temporal Pattern of Side Effects

Side effects are not stable over time—some resolve while others emerge during the course of therapy 2:

• Dry mouth, mask leakage, and nasal congestion can emerge within 1 year in approximately 30% of patients who did not experience them after 2 weeks of use 2
• Early side effects (within 1-2 weeks), particularly increased awakenings and dry mouth, are significantly associated with treatment dropout during the first year and reduced machine usage 2

Impact on Adherence

While side effects are common, most do not significantly impact long-term adherence 2:

• Only 27% of patients reduce CPAP use because of side effects 4
• Overall compliance remains high at 88% of patients using their device nightly, with average daily use of 6.5 hours, because clinical benefits outweigh side effects 3
• The benefits of PAP therapy for symptomatic OSA (reduction in sleepiness, improved quality of life) outweigh the potential harms of transient side effects 1, 7

Effective Mitigation Strategies

Mask Selection

Clinicians should use nasal or intranasal mask interfaces over oronasal or oral interfaces for routine PAP initiation, as nasal masks produce fewer side effects and significantly improve adherence 1, 7:

• Meta-analyses demonstrate clinically significant improvement in adherence with nasal PAP versus oronasal interfaces 1
• Nasal interfaces are associated with fewer side effects compared to oronasal and oral interfaces 1
• Individually molded masks reduce nasal bridge abrasions (p<0.01) and red eyes (9% vs 24%, p<0.025) compared to standard silicone masks 3

Humidification

Adding heated humidification to CPAP significantly reduces multiple side effects and should be routinely used 1, 8, 7:

• Meta-analyses demonstrate clinically significant reduction in dry mouth/throat, nasal discharge, nasal congestion, dry nose, nosebleeds, sinus pain/headache, sore throat, hoarse voice, and reduced smell 1
• Heated humidification is a standard recommendation to improve CPAP utilization 8
• The benefits outweigh potential "rain out" (condensation) and modest ongoing costs 1

Pressure Management

For patients intolerant of high pressures or experiencing persistent side effects, several pressure modifications can be implemented 9, 7:

• Switch from CPAP to bilevel PAP (BPAP) if the patient is uncomfortable with high pressures or if obstructive events continue at 15 cm H₂O 9
• Auto-adjusting PAP (APAP) may lower average nightly pressure exposure while maintaining therapeutic control 7
• Use the minimum effective pressure required to control sleep apnea to reduce middle-ear pressure elevation 7
• Utilize the device's ramp feature to gradually increase pressure at sleep onset 7

Symptom-Specific Management

For ear pain: Use acetaminophen or NSAIDs for mild-to-moderate pain; refer to otolaryngology if symptoms persist despite interventions 7

For aerophagia/gastric symptoms: Consider pressure reduction if clinically appropriate, or switch to BPAP 6

For nasal congestion: Use nasal steroids, consider turbinate surgery or infiltration 4

Critical Follow-Up Considerations

Close follow-up by trained healthcare providers is essential, especially during the first few weeks of PAP use, to establish effective utilization patterns and remediate problems promptly 8:

• CPAP usage should be objectively monitored with time meters to ensure adequate utilization 8
• If CPAP use is inadequate based on objective monitoring and symptom evaluation, implement prompt and intensive efforts to improve PAP use or consider alternative therapies 8
• Do not discontinue CPAP therapy solely because of side effects—the cardiovascular and quality-of-life benefits of treating OSA outweigh transient ear or other symptoms 7

Equipment Maintenance

Equipment condition deteriorates over time and requires attention 4:

• After >1 year of use, the percentage of equipment in fine condition drops significantly: silicone interface (87% to 44%), mask-connectors (74% to 44%), air tube (83% to 44%), and head strap (91% to 78%) 4
• Common defects include stiffness of silicone interface, cracks in interface/connectors/tubing, and loose connections 4
• Regular equipment inspection and replacement is necessary for effective treatment 4