Continuous Positive Airway Pressure (CPAP) therapy is the most common and effective treatment for Obstructive Sleep Apnea. It delivers a constant stream of pressurized air through a mask to keep the upper airway open during sleep. While CPAP significantly improves sleep quality, many users notice increased respiratory mucus, phlegm buildup, or persistent nasal congestion related to the continuous airflow.
The Connection Between CPAP and Respiratory Mucus
The sensation of increased phlegm or congestion results from the body’s natural defense mechanism responding to irritation. The delicate lining of the nasal passages, known as the nasal mucosa, warms and humidifies the air before it reaches the lungs. When using a CPAP, the high volume of pressurized air constantly flowing through these passages can disrupt this natural process.
This constant flow, even if slightly humidified, can strip away natural moisture from the mucosal tissues. As the nasal lining dries out, the body attempts to overcompensate by significantly increasing mucus production. This excessive mucus is an inflammatory response to the dryness and irritation.
Furthermore, the mechanical compression and constant air pressure itself can trigger an inflammatory reaction within the nasal tissues. Studies suggest this continuous physical stimulus can cause swelling and irritation, leading to a condition sometimes referred to as CPAP rhinitis. This irritation exacerbates the body’s need to produce more mucus, resulting in the congestion and phlegm buildup users experience. High-pressure settings or air leaks, especially through the mouth, can intensify this effect by increasing the drying and irritating flow across the airways.
Optimizing Your CPAP Settings for Phlegm Reduction
Adjusting your CPAP equipment and settings is the most effective way to manage and reduce phlegm and congestion. The primary tool for this is the heated humidifier, which is designed to reintroduce moisture into the pressurized air stream. Finding the correct humidity setting is a balancing act, as too little moisture causes dryness and overproduction of mucus, while too much can cause a different issue.
Excessive humidity can lead to “rainout,” where warm, moist air cools rapidly in the tubing and turns into condensation. This water then enters the mask, creating a wet, gurgling sensation that users often mistake for excess mucus in the airways. To prevent this, most modern machines can be paired with heated tubing.
Heated tubing maintains the temperature of the air from the humidifier all the way to the mask, preventing the air from cooling and condensing into water droplets. Synchronizing the heat setting on the humidifier with the heat setting on the tubing helps deliver comfortably warm, moist air, significantly reducing both rainout and the drying effect on the nasal passages. This combination is often the most effective adjustment for respiratory comfort.
Another crucial factor is the regular cleaning and maintenance of your CPAP system components. Over time, the mask, tubing, and especially the water reservoir can accumulate mineral deposits, bacteria, mold, or allergens. Breathing in these contaminants can directly irritate the airway lining, triggering an inflammatory response that includes increased phlegm production. Daily rinsing of the water chamber and weekly cleaning of the mask and tubing with mild soap and distilled water can prevent this buildup.
Recognizing When Symptoms Require Medical Attention
While mild congestion and phlegm are common, manageable side effects of CPAP therapy, certain symptoms warrant a consultation with a healthcare provider or sleep specialist. If congestion or phlegm persists despite optimizing the humidifier, using heated tubing, and practicing rigorous cleaning, the issue may be unrelated to the machine’s function.
Signs that require medical attention include phlegm that is thick, discolored, or foul-smelling, which can indicate a sinus or respiratory infection. A persistent fever, chest pain, or an inability to clear the throat could also signal a condition requiring treatment beyond simple CPAP adjustments.
In some cases, chronic symptoms may be linked to underlying issues like seasonal allergies or nasal anatomical problems that are exacerbated by the forced air. Your sleep specialist can evaluate the possibility of CPAP rhinitis, which may require a prescription nasal steroid spray or antihistamine to reduce inflammation. They can also review your specific pressure settings, as an unnecessarily high pressure can intensify mucosal irritation. Consulting a professional ensures persistent respiratory discomfort is properly diagnosed and treated, helping you remain compliant with therapy.