A CPAP cough is an irritating, reflex cough or throat dryness experienced by users of Continuous Positive Airway Pressure (CPAP) therapy. The continuous flow of pressurized air can dry out the delicate mucosal lining of the nose and throat, triggering an uncomfortable, persistent cough. This common side effect often disrupts sleep and leads to decreased adherence to therapy. Fortunately, this issue is rarely serious and can usually be resolved through methodical adjustments to the equipment and addressing underlying health factors.
Addressing Air Quality and Moisture Settings
The single most frequent cause of CPAP cough is the delivery of air with insufficient moisture, which irritates the upper airway. Adding a heated humidifier to the CPAP machine is the primary way to combat this dryness, as it introduces warm moisture into the pressurized airflow. Users should experiment with increasing the humidity setting gradually until the throat and nasal passages feel comfortable and moist upon waking.
Always use distilled water in the humidifier to prevent mineral deposits from accumulating in the water tank. These deposits can damage the machine and harbor microorganisms. Regular, thorough cleaning of the water chamber, mask, and tubing is necessary to prevent the inhalation of mold, bacteria, or other irritants that can cause lung inflammation and trigger a persistent cough.
A phenomenon known as “rainout,” where humidified air cools in the tubing and turns into water droplets, can also cause irritation. This condensation can gurgle into the mask, prompting a cough reflex. The solution is often to use a heated tube, which maintains a consistent temperature throughout the tube’s length, preventing the warm, moist air from condensing before it reaches the mask. Some modern machines feature automatic climate control technology that adjusts the temperature of both the humidifier and the tubing to maintain a precise and comfortable level of relative humidity.
Optimizing Machine Pressure and Mask Fit
Coughing can be a mechanical reaction related to the pressure settings or the physical seal of the mask against the face. If the prescribed air pressure feels too forceful, it can trigger a natural cough reflex in the airway. The “ramp” feature is helpful, as it starts the pressure at a low, comfortable level and gradually increases it to the therapeutic setting, allowing the user to fall asleep before the full pressure is reached.
Some machines offer exhalation pressure relief technology, which temporarily lowers the pressure upon exhale. This feature makes it easier to breathe out against the constant flow of air, minimizing the likelihood of a pressure-induced cough. The physical interface between the machine and the user is equally important, as a poor mask fit can cause air leaks that blow pressurized air directly onto the face, eyes, or throat, leading to localized dryness and irritation.
To ensure a proper seal, adjust the headgear so the mask is snug but not overly tight, as overtightening can distort the cushion and create new leaks. Leaks, especially those around the mouth, can rapidly dry the throat, which is a common trigger for coughing. If using a nasal mask and mouth leaks are suspected, switching to a full-face mask or using a chin strap may be necessary to maintain the seal and prevent air from escaping.
Ruling Out Underlying Health Contributors
If equipment adjustments do not resolve the cough, the cause may be related to an underlying health condition exacerbated by CPAP use. Gastroesophageal Reflux Disease (GERD), or chronic acid reflux, is frequently linked to a persistent cough, especially one that occurs at night. The continuous positive pressure from the machine may push stomach acid up into the esophagus and throat, causing irritation and a reflex cough.
Nighttime post-nasal drip, often caused by allergies or sinus issues, is another common non-CPAP contributor to coughing. The constant airflow from the CPAP machine can sometimes worsen the symptoms of seasonal allergies or chronic congestion. Using a nasal saline rinse before therapy may clear the nasal passages and reduce the drip that pools in the throat overnight.
A persistent cough that lasts more than a few weeks, even after making all recommended adjustments, warrants a consultation with a physician. It is important to rule out non-CPAP related issues such as a respiratory infection, cough-variant asthma, or other serious conditions. Any cough accompanied by chest pain, blood, or fever requires immediate medical attention.