CPAP therapy is the most effective treatment for obstructive sleep apnea, but it comes with a real list of side effects that range from minor annoyances to issues significant enough that up to a quarter of users eventually stop treatment. Most problems fall into a few predictable categories: mask discomfort, nasal and airway dryness, swallowed air, skin irritation, and sleep disruption from noise or poor fit. Understanding what’s behind each issue makes them much easier to fix.
Nasal Dryness, Congestion, and Nosebleeds
The most frequently reported CPAP complaints involve the nose. Pressurized air flowing through your nasal passages for hours strips away moisture, leaving you with a dry, irritated nose that can progress to crusting, congestion, or nosebleeds. A leaky mask makes this worse because it pulls even more moisture from nasal tissue as air escapes and is replaced.
Most CPAP machines now come with a heated humidifier attachment that adds moisture to the airstream before it reaches your airway. Adjusting the humidification level up, using a nasal saline spray before bed, or switching from a nasal mask to a full-face mask that covers both nose and mouth can all reduce dryness. If congestion is persistent, it’s worth checking that your mask fits properly. Constant strap tightening to stop leaks is a sign the mask shape doesn’t match your face.
Air Swallowing and Stomach Problems
About 16% of CPAP users experience aerophagia, which simply means swallowing air from the machine during sleep. It happens because the muscles in your esophagus relax overnight, and the pressurized airstream can push air down into your stomach instead of staying in your airway.
The result is a buildup of gas in your digestive system that can cause bloating, excessive belching, flatulence, stomach pain, nausea, and sometimes diarrhea. Some people wake up feeling uncomfortably full or notice chest tightness. Higher pressure settings increase the likelihood, so if your machine uses auto-adjusting pressure, the problem may come and go depending on what pressure the machine delivers on a given night. Sleeping with your head slightly elevated or switching to a machine that lowers pressure when you exhale can help reduce the amount of air that reaches your stomach.
Mask Leaks and Reduced Treatment
Unintentional mask leaks are the single most common cause of CPAP side effects and the primary reason people abandon therapy. A leak does two things at once: it creates the conditions for other problems (dry nose, dry eyes, skin irritation) and it reduces the air pressure actually reaching your airway. That means apnea events can continue even while the machine is running, which defeats the purpose of treatment.
Leaks typically come from a mask that doesn’t match the contours of your face, a cushion that has worn out and lost its seal, or pressure settings that are higher than the mask can contain. The fix isn’t simply tightening the straps. Over-tightening distorts the cushion and often makes leaks worse while also creating pressure sores. A properly fitting mask should feel secure with moderate strap tension and leave no gaps around the edges.
Skin Irritation and Pressure Sores
Wearing a mask strapped to your face for six to eight hours creates friction, pressure, and a warm, moist environment against your skin. This combination can lead to redness, irritation, contact dermatitis, and in some cases actual pressure sores, particularly on the bridge of the nose and cheeks where the mask sits. People with sensitive skin or who over-tighten their straps are most vulnerable.
Switching mask styles is often the most effective solution. Nasal pillow masks, which sit at the nostrils rather than across the face, eliminate contact with the bridge of the nose entirely. Mask liners, thin fabric covers that sit between the cushion and your skin, can also reduce friction and absorb moisture. Cleaning the mask cushion daily prevents oil and bacteria buildup that contributes to breakouts.
Dry Eyes
Air leaking upward from the top of a nasal or full-face mask blows directly across the eyes during sleep. Over hours, this dries out the surface of the eye and can cause irritation, redness, and blurry vision in the morning. The problem is almost always a fit issue rather than something inherent to CPAP therapy. Adjusting the mask position so the seal sits below the eye sockets, or trying a different mask shape, usually resolves it.
Treatment-Emergent Central Sleep Apnea
This is a less common but more significant problem. In roughly 5% to 20% of people starting CPAP, the brain temporarily loses its normal breathing rhythm once the airway obstruction is removed, causing a different type of apnea where the brain simply stops sending the signal to breathe. This is called treatment-emergent central sleep apnea, and it shows up as persistent apnea events on your machine’s data despite the airway being held open.
The reassuring part is that in more than half of cases, this resolves on its own within the first few months of therapy as the brain adjusts. For the remainder, a different type of device that varies pressure more dynamically may be needed. If you’ve been on CPAP for a few weeks and still feel unrefreshed or your machine reports a high number of events, this is one possible explanation worth investigating with your sleep specialist.
Noise and Sleep Disruption
Modern CPAP machines are significantly quieter than older models, but they still produce some noise, and mask leaks can add a whistling or hissing sound on top of that. For light sleepers or bed partners, the noise can fragment sleep enough to become a problem in its own right. Ensuring a good mask seal eliminates most whistling. Placing the machine on a soft surface like a towel, or slightly below bed level, can also reduce perceived noise.
Infection and Hygiene Concerns
CPAP masks, tubing, and humidifier chambers can accumulate bacteria and fungi over time. Studies examining the devices of regular users have found substantial contamination on both external components like the mask and tube, and internal components like the humidifier chamber. Despite this, documented infections directly linked to contaminated CPAP equipment are rare. At least one case of Legionella pneumonia has been reported, but large-scale studies have not found increased rates of upper or lower respiratory infections among CPAP users.
That said, regular cleaning reduces risk. Washing the mask cushion daily with mild soap, cleaning the tubing and humidifier chamber weekly, and replacing filters on schedule keeps bacterial growth in check. Using distilled water in the humidifier prevents mineral buildup and removes a potential food source for microorganisms.
Why People Stop Using CPAP
Compliance drops noticeably over time. In one 2025 study, 95.8% of users were still on therapy at one month, but that fell to 75% by six months. Side effects are a major driver, but they’re not the only one. Among people who refused CPAP from the start, the most common reasons were preference for alternative treatments (39.3%), social stigma around wearing the device (35.7%), and financial constraints (28.6%).
Most side effects are solvable with relatively simple adjustments: a different mask style, a humidifier setting change, or a pressure adjustment. The users who stick with CPAP long-term tend to report significant subjective improvement in daytime sleepiness, energy, and overall sleep quality, which is what motivates them through the adjustment period. If you’re experiencing problems, the fix is usually a matter of equipment and settings rather than a reason to abandon treatment entirely.