CPAP side effects: causes and solutions

CPAP side effects: causes and solutions

CPAP therapy is the gold-standard treatment for sleep apnoea - but it can cause discomfort, especially during the first weeks of use. The good news: the vast majority of these side effects have a concrete solution, often a simple accessory or a settings adjustment. This guide helps you identify the problem and resolve it.

Overview: summary table

1. Dry mouth

Dry mouth is the most common CPAP side effect and the leading cause of therapy abandonment. It occurs when you breathe partially through your mouth at night: pressurised air escapes through the mouth instead of staying in the airways. Absent or insufficient humidification worsens the problem.

Causes:

• Mouth breathing during sleep (mouth opens involuntarily)
• No humidifier or humidifier set too low
• Mask leaks that dry the surrounding air
• Nasal mask that does not cover the mouth

Solutions:

• Activate or increase the heated humidifier integrated into your device (level 3-4 out of 5 recommended)
• Add a heated tube (ClimateLineAir 11 for AirSense 11, ClimateLineAir for AirSense 10) to keep humidity all the way to the mask
• Wear a chin strap to keep your mouth closed during sleep
• Switch to a full-face mask covering both nose and mouth if mouth breathing is chronic
• Drink a large glass of water before going to bed

2. Nasal congestion

Nasal congestion under CPAP is caused by the delivered air being colder and drier than ambient air. The nasal mucosa reacts by producing more mucus to compensate for the dryness, creating a blocked-nose feeling upon waking.

Solutions:

• Heated humidifier - the primary and most effective solution
• Saline nasal spray (e.g. Humer, Physiomer) a few minutes before putting on the mask
• Heated tube (ClimateLineAir 11) to prevent humidity from condensing in transit
• Treat underlying allergy if allergic rhinitis is confirmed
• Avoid placing the tube on a cold floor in winter

3. Rainout - condensation in the tube

Rainout refers to water condensing inside the CPAP tube. You may hear a gurgling sound or receive water droplets in your mask during the night. This happens when warm, humidified air cools as it travels through the tube and turns back into liquid - typically in winter or in a cool bedroom.

Solutions:

• ClimateLineAir 11 heated tube (compatible with AirSense 11) or ClimateLineAir (compatible with AirSense 10): keeps air warm throughout the tube and virtually eliminates rainout
• Reduce the humidification level slightly
• Cover the tube with an insulating sleeve (tube wrap)
• Route the tube under the duvet to benefit from body heat

4. Aerophagia and bloating

Aerophagia (swallowing air) manifests as bloating, gas, and burping, especially upon waking. It often signals that your CPAP pressure is too high or poorly calibrated: pressurised air is being swallowed into the oesophagus rather than inhaled into the lungs.

Solutions:

• Consult your doctor to reassess the pressure setting - this is the primary solution
• Switch to an Auto-CPAP (AirSense 11 AutoSet, DreamStation 2) that adjusts pressure to the minimum needed
• Activate EPR (ResMed) or SoftPAP (Löwenstein) - reduces pressure during exhalation
• Raise the head of the bed by 15 to 30 cm
• Avoid eating in the 2 hours before bedtime

5. Claustrophobia and mask discomfort

A feeling of confinement or suffocation related to the mask is common at the start of therapy, especially in people with an anxious disposition. It can cause panic awakenings or a refusal to wear the mask.

Solutions:

• Start by wearing the mask during the day, without the machine, to get used to it gradually
• Choose a nasal pillows mask - small inserts in the nostrils that leave the face largely uncovered
• Wear the mask with the machine running for a few minutes before going to sleep (ramp mode activated)
• Practise slow, deep breathing when putting on the mask
• If anxiety is severe, discuss this with your doctor

Browse our CPAP masks and read our CPAP mask selection guide to find the best fit for your face shape.

6. Skin irritations and mask marks

Redness, marks, and irritations appear when the mask presses too hard on the skin. A mask that leaves marks still visible more than an hour after waking is too tight. Over time, excessive mask tightness can cause skin lesions or contact allergy.

Solutions:

• Loosen the straps - test: you should be able to slide a finger under each strap. Never compensate for a leak by tightening further
• Use protective cushion pads in fabric or gel (NasalPad, Remzzz) between the mask and your skin
• Try a different cushion size (S/M/L): an undersized cushion leaks and forces you to over-tighten
• Replace the worn cushion every 3 to 6 months (it loses its seal and flexibility)
• Clean the mask daily to prevent the build-up of sebum and bacteria

7. Machine or mask noise

Modern CPAP devices are very quiet (25-30 dB, quieter than a refrigerator). Almost all audible noise comes from the mask - leaks, whistling, gurgling - and not from the machine itself.

Solutions:

• Reduce mask leaks (see irritations and claustrophobia sections)
• Route the tube behind the head rather than to the side
• Place the machine on an absorbent surface (thick towel, non-slip mat)
• Check and replace the machine filter regularly
• Use a heated tube to eliminate gurgling from rainout

8. Dry or irritated eyes (mask leaks)

Leaks around the nose or cheeks direct a stream of cold air towards the eyes during the night. Upon waking: red, irritated, dry eyes, or recurring conjunctivitis. This is a sign that the mask seal is compromised.

Solutions:

• Readjust the straps - reposition rather than tighten further
• Try a different cushion size (an undersized cushion leaks sideways)
• Replace the worn cushion - change every 3 to 6 months according to the manufacturer
• Try a different mask type (CPAP mask guide)
• Check your leak rate in your device data (ideally below 24 L/min for ResMed)

When to consult a doctor?

Some side effects require medical consultation rather than a simple accessory adjustment:

• Persistent aerophagia despite pressure adjustment
• High residual apnoeas (AHI > 5 on a regular basis)
• Frequent nosebleeds
• Appearance of central apnoeas in CPAP data
• Persistent morning headaches