Using someone else’s CPAP machine is technically possible but comes with real medical and safety risks that make it a bad idea in most situations. CPAP devices are prescription medical equipment in the United States, meaning they are legally set to deliver a specific air pressure tailored to one person’s sleep apnea severity. Borrowing or buying a used machine means breathing through equipment calibrated for someone else’s anatomy and condition, with the added concern of inhaling whatever microorganisms the previous user left behind. There are legitimate pathways to get affordable or even free CPAP therapy, but grabbing a friend’s old machine off the nightstand is not one of them.
Why CPAP Machines Are Prescription Devices
A CPAP machine is not a one-size-fits-all appliance. The core purpose of the device is to push a continuous stream of air at a prescribed pressure, measured in centimeters of water pressure, into your airway to keep it from collapsing during sleep. That pressure is determined during a sleep study or titration session, where a technician or algorithm figures out the lowest effective setting for your particular obstruction. Some people need relatively low pressure, others need substantially more, and using the wrong setting can mean the machine either fails to prevent apneas or blows air so forcefully that it causes discomfort, aerophagia (swallowing air into the stomach), or central apneas triggered by excessive pressure.
Because the therapeutic pressure varies so much from person to person, the FDA classifies CPAP devices as Class II medical devices requiring a prescription. A doctor or sleep specialist writes that prescription based on your individual results. When you pick up someone else’s machine, you are inheriting their prescription, not yours. Even if you happen to have a similar severity of sleep apnea, the odds that another person’s exact pressure setting matches what you need are slim.
The Infection Problem Is Not Hypothetical
CPAP machines are warm, moist, enclosed systems, which is exactly the environment bacteria and fungi love. A study examining devices used by 55 sleep apnea patients found substantial contamination on both external parts like the mask and tubing and internal components including the humidifier chamber and the interior of the main body.1PubMed Central. Level of Contamination of Positive Airway Pressure Devices Used in Obstructive Sleep Apnea A separate microbiome analysis of CPAP devices found bacteria in about a quarter of tubes tested and in over 80 percent of filters, with fungi detected in roughly 60 percent of filters as well.2Clinical and Experimental Otorhinolaryngology. Microbiome and Mycobiome Analyses of Continuous Positive Airway Pressure Devices
These are not just benign environmental organisms. Pseudomonas aeruginosa, a waterborne pathogen that thrives in humid conditions, has been documented colonizing poorly maintained CPAP equipment and causing pneumonia, particularly in people with weakened immune systems or lung conditions like COPD.3PubMed Central. Pseudomonas Unmasked: Poor Continuous Positive Airway Pressure (CPAP) Hygiene Leads to a Case of Pseudomonas Pneumonia When you use someone else’s machine, you are breathing through a system that has been colonized by their unique bacterial flora for months or years. Even if the previous owner was healthy, their microbial environment is not yours, and the warm humid air being pushed into your lungs gives those organisms a direct pathway deep into your respiratory tract.
Can You Just Clean It Thoroughly?
This is usually the first follow-up question, and the answer is more complicated than it sounds. You can certainly wash the mask, tubing, and humidifier chamber with mild soap and warm water, which is the standard daily or weekly maintenance recommended by device manufacturers. Replacing the mask, tubing, and filters entirely is even better if you are acquiring a used machine. But cleaning the internal components of the machine itself, the part where air is pressurized and moved through the device, is not straightforward for a consumer. Those internal pathways are not designed to be opened and scrubbed.
You might assume that aftermarket cleaning gadgets solve this. Devices that use ozone gas or ultraviolet light to sanitize CPAP equipment have been heavily marketed, but the FDA has raised serious concerns about them. Between 2017 and 2019, the agency received reports from patients who developed coughs, difficulty breathing, nasal irritation, headaches, or asthma attacks after using ozone-based cleaning products on their CPAP gear.4JAMA. Warning About Cleaning CPAP Devices With Ozone Gas, UV Light Beyond the direct irritation from residual ozone, these unregulated cleaning devices have been implicated in degrading the foam and other materials inside CPAP machines, potentially releasing harmful chemicals.5Annals of the American Thoracic Society. Providing Cleaning Recommendations for Positive Airway Pressure Devices So aggressive cleaning of a borrowed machine can actually introduce new risks rather than eliminating old ones.
The practical upshot: you can sanitize the replaceable external parts or just buy new ones, but the internal air pathway of a used machine is difficult to verify as clean, and the tools marketed for deep-cleaning can do more harm than good.
Mask Fit Matters More Than People Think
Even if the pressure were magically correct and the machine spotlessly clean, you would still face the mask problem. CPAP masks come in different styles (nasal pillows, nasal masks, full-face masks) and a wide range of sizes. The mask that came with someone else’s machine was fitted to their face. A poor-fitting mask leaks air, and leak-related side effects are the single most common complaint among long-term CPAP users. One large real-world study found that about three-quarters of patients reported leak-related problems, and those leaks were significantly associated with residual excessive sleepiness and with symptoms like dry mouth and dry nose that drive people to stop using their machines altogether.6PubMed Central. Mask side-effects in long-term CPAP-patients impact adherence and sleepiness: the InterfaceVent real-life study
A borrowed machine with a borrowed mask is almost guaranteed to leak more than a properly fitted setup. The leaks are not just annoying: they reduce the effective pressure reaching your airway, which means the machine may not be treating your apnea even if the pressure dial reads the right number. And the dry mouth and nasal irritation from leaking air makes the whole experience miserable enough that many people give up on therapy entirely. If you are considering someone else’s machine as a stopgap, replacing the mask with one professionally fitted to your face is the bare minimum.
The Age and Condition of the Device
CPAP machines are not built to last forever. Most manufacturers recommend replacing the device every five years or so, and the internal components degrade over time. Filters lose their effectiveness, seals wear out, and the motor that generates pressure can drift from its calibrated output. If you are inheriting a machine that has been sitting in a closet for years, there is no easy way to verify that it still delivers the pressure it displays.
The Philips Respironics recall in 2021 highlighted a more dramatic version of this risk. Millions of CPAP and BiPAP devices were recalled because the sound-abatement foam inside the machines could break down and release particles and potentially toxic gases into the air stream. Health authorities raised concerns about the respiratory and other risks of inhaling degraded polyurethane foam.7PubMed Central. Health risks related to polyurethane foam degradation in CPAP devices used for sleep apnoea treatment If someone hands you their old machine and it happens to be a recalled model, you could be breathing in degraded foam particles every night. Checking the device’s model number against the recall list is essential, but it is the kind of step many people skip when they are just trying to get something that works.
Humidity Settings and Comfort
Most modern CPAP machines include a heated humidifier to add moisture to the pressurized air. Without humidification, the constant airflow dries out the nasal passages and throat, leading to congestion, nosebleeds, and sore throats. But the right humidity level depends on your local climate, the season, and your individual sensitivity. Research measuring the air conditions inside CPAP masks found that absolute humidity and temperature were significantly lower in winter than in summer under all tested humidification conditions. Using a heated tube (sometimes called a climate line) helped maintain more consistent humidity in cold weather compared to standard humidification or no humidification at all.8PubMed Central. Mask humidity during CPAP: influence of ambient temperature, heated humidification and heated tubing
Someone else’s machine may have humidity settings tuned for their comfort level and their climate. If you live in a dry winter environment and inherit a machine set up for a humid coastal home, the air you breathe will feel different. This is fixable with some experimentation, but it is one more variable to adjust on top of the pressure and mask problems. If the borrowed machine is an older model without a heated tube, winter use may be genuinely uncomfortable no matter what you do with the humidifier dial.
What About Auto-Adjusting Machines?
Some people argue that an auto-titrating (APAP) machine sidesteps the pressure problem because it adjusts on the fly rather than delivering a single fixed pressure. APAP devices continuously monitor your breathing and increase or decrease pressure within a set range to respond to apneas and hypopneas in real time. If the borrowed machine is an APAP set to a wide enough range, it might land on an effective pressure for you even though it was prescribed for someone else.
This is the strongest argument in favor of borrowing, and it has some merit. But it still requires that the minimum and maximum pressure boundaries be appropriate for your condition. If the previous owner had mild apnea and the device’s range tops out at a pressure below what you need, the machine will hit its ceiling and still leave your airway partially obstructed. More fundamentally, you are flying blind without a sleep study to confirm that the auto-titration is actually working. CPAP machines report data like residual apnea index and leak rates, but interpreting that data properly usually requires a clinician who can compare it against your baseline and adjust accordingly. Self-treating with a borrowed APAP is better than nothing for someone who genuinely cannot access care, but it is a far cry from proper treatment.
Legitimate Ways to Get Affordable CPAP Therapy
The reason most people consider borrowing a machine in the first place is cost. Without insurance, a new CPAP setup with a machine, mask, tubing, and humidifier can run into the hundreds or even over a thousand dollars. Insurance coverage varies and often requires documentation of a sleep study. For people without coverage or in underserved areas, the barrier feels impossibly high.
Some sleep medicine programs have recognized this gap and created formal donation and refurbishment programs. One clinical outreach initiative described in the sleep medicine literature developed a process for accepting donated PAP devices, refurbishing them to safe working condition, recalibrating the pressure settings under clinical supervision, and providing them to patients who had been diagnosed with or were suspected of having obstructive sleep apnea, all at no cost.9PubMed Central. Safe use of donated positive airway pressure devices to increase access to treatment for obstructive sleep apnea: a clinical outreach program Programs like this replace consumable parts, verify the device is functioning correctly, and pair the machine with a proper prescription. They represent the safe version of what borrowing tries to accomplish informally.
Beyond donation programs, some options worth exploring include durable medical equipment (DME) suppliers that sell refurbished machines with new masks and tubing at reduced prices, patient assistance programs run by manufacturers, and community health centers that may help navigate insurance paperwork or Medicaid coverage. Telehealth sleep medicine services have also expanded access to prescriptions in areas without local sleep labs, sometimes bundling the prescription with equipment at competitive prices.
When People Use Borrowed Machines Anyway
All of the above risks are real, but it is worth acknowledging that some people end up using someone else’s machine because the alternative is untreated severe sleep apnea. Untreated obstructive sleep apnea carries its own serious risks: daytime sleepiness that causes car accidents, cardiovascular strain including high blood pressure and increased heart attack and stroke risk, and a generally miserable quality of life. A person with severe sleep apnea who borrows a machine with roughly appropriate settings and a new mask is probably better off than a person with severe sleep apnea who does nothing while waiting months for insurance approval.
If you find yourself in that situation, the pragmatic minimum would be: replace every part that touches your face or carries air (mask, tubing, filters, humidifier chamber). Verify the machine is not on any recall list. If possible, have a sleep specialist review the pressure settings. And treat it as a bridge, not a permanent solution. Get a proper prescription and your own device as soon as you can, because the risks of a borrowed machine compound over time as the device ages and as your own condition potentially changes.
The Resale Market and Its Pitfalls
Used CPAP machines are widely available on online marketplaces and through secondhand medical equipment sites. The legal situation is murky. Because CPAP devices require a prescription, selling them without verifying the buyer has one falls into a regulatory gray area. Some sellers skirt this by listing them as “for parts” or requiring buyers to upload a prescription. Others do not bother with any verification at all.
Buying from the resale market carries all the risks described above, plus a few extras. You typically have no way to verify the device’s maintenance history, its total hours of use, or whether it has been exposed to ozone cleaning products that may have degraded internal components. The machine’s data card, which stores usage and performance information, may have been wiped or may contain the previous owner’s health data. And there is no manufacturer warranty on a secondhand device, meaning if the motor fails or the pressure sensor drifts, you are out whatever you paid with no recourse. For people who go this route, sticking to more recent models from reputable brands, verifying the model against recall databases, and budgeting for all-new consumable parts is the minimum due diligence.