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How to Prevent CPAP Dry Mouth

CPAP machines are used to treat obstructive sleep apnea (OSA), a sleep disorder that can lead to gaps in breathing during sleep due to an airway restriction A CPAP delivers a constant stream of pressurized air through a hose and mask, which helps breathing by keeping the upper airway open. While CPAP machines can help alleviate OSA symptoms and improve the user’s quality of life, this therapy can come with unwanted side effects, including dry mouth – or xerostomia. 

Dry mouth is a reported CPAP side effect1 and a reason people may discontinue CPAP therapy2. If you’re experiencing dry mouth while using your CPAP machine, don’t despair – we’ll explain what can cause it, ways to prevent it, and what you should do if symptoms persist. 

Why Do CPAP Machines Cause Dry Mouth?

There are several reasons why you might experience dry mouth while using your CPAP machine, including a poorly-fitted mask, the flow of pressurized air decreasing saliva production, mouth breathing, and a lack of humidification.

  • Decreased saliva – Pressurized air flowing through the nasal cavity can affect saliva production3 because the nose and mouth are connected via the nasopharynx (the top part of your throat). Decreased saliva production can leave you with a dry, uncomfortable mouth.
  • Mouth breathing – Breathing through the mouth can dry up the saliva4 that usually keeps your mouth moist. However, the constant flow of air from a CPAP can exacerbate this. CPAP users who breathe through their nose but sleep with their mouth open may also experience dry mouth due to pressurized air escaping through the mouth and drying it out5.
  • Dry air – Your CPAP draws in air from the environment, so unless a humidifier is used in the machine or room, those living in low-humidity climates can receive a pressurized stream of dry air, further zapping moisture from the mouth. 

Other Causes of Dry Mouth

Dry mouth during CPAP therapy may not necessarily be caused by your PAP device; there are a host of reasons why you might be experiencing decreased saliva, and it may be helpful to rule them out first.

  • Medication – Dry mouth is a side effect of some medications6, both prescription and over-the-counter, resulting from the medicine decreasing saliva production. Medication that often causes dry mouth includes those used to treat depression, anxiety, high blood pressure, and Parkinson’s.6 It can also be an issue with antihistamines, decongestants, and certain pain relievers.
  • Illnesses – Certain health conditions can increase dry mouth7, including diabetes, HIV/AIDS, stroke, autoimmune diseases, and Alzheimer’s. 
  • Dehydration – Dehydration occurs when the body loses more water than it’s taking in. Water is crucial for the body to function properly, as it’s made of up to 65 percent water8. Feeling thirsty is a sign that you’re already dehydrated. In addition to dry mouth, dehydration can cause tiredness, headaches, and constipation9.
  • Salivary gland issues – Sialothiasis10 is a rare condition in which stones form in the salivary glands and block the flow of saliva. This causes pain, swelling, and dry mouth. The condition is more prevalent among males aged 30 to 60 years old.11 Swollen salivary glands, or sialadenitis11, can also cause a decrease in saliva, as well as pain while eating, swelling, and fever. Some causes of sialadenitis are dehydration, poor oral hygiene, infection, and certain medications.11
  • Tobacco – Research shows that smoking cigarettes can increase the risk of dry mouth12. Additionally, some recent research13 found that e-cigarette users are even more likely than traditional cigarette smokers to experience dry mouth.
  • Marijuana – Smoking cannabis is linked to a decrease in saliva production14, which can lead to dry mouth. It’s thought that tetrahydrocannabinol (THC), which is the main compound in cannabis, can negatively impact salivary glands.14
  • Stress/anxiety – Several studies15 show a link between stress and anxiety, and a significant reduction in salivary flow​​.​​ The sympathetic and parasympathetic nervous systems control the salivary glands16. The sympathetic nervous system is activated when you’re stressed, triggering the body’s “fight or flight” response17, which diverts energy to body parts that may help you escape danger, including slowing down digestion. During this process, saliva becomes thicker to prohibit the first part of the digestive process, which can cause the mouth to dry out.

Tips to Prevent CPAP Dry Mouth 


Using a humidifier with your CPAP adds moisture to the air you breathe, which can reduce the risk of dry mouth. With a humidifier, the air is moistened when it passes over a chamber of distilled water before being delivered through the mask. Humidifiers are either built into the machine or attached externally. Another way to add moisture is to use heated tubing with your CPAP machine. 

Explore: Best Humidifiers for The Bedroom

Breathe Through Your Nose

Breathing through your nose instead of your mouth could help alleviate dryness since mouth breathing dries up saliva, which can cause dry mouth.5 For those who already breathe through your nose but keep their mouth open when they sleep, which could also cause dryness, a CPAP chin strap could help. The chin strap gently keeps the mouth closed18, and it can lessen unintentional air leaks. 

Relieve Nasal Congestion

Nasal congestion can cause you to breathe through your mouth, which means relieving the congestion could help. You can try using a saline spray19 to lubricate the nose and get rid of mucus. If the congestion is caused by allergies, a pharmacist can advise you on the most appropriate remedies.

Try a Different Style of Mask 

Research shows that dry mouth is more common among users of oronasal masks20 than those who use nasal masks or nasal pillows. This may be because oronasal masks appear to leak more than nasal masks21, which can cause dry mouth. Therefore, it might be worth speaking to your doctor about trying out a nasal-type mask instead. 

Find the Best Nasal CPAP Masks.

Stay Hydrated 

Not consuming enough water can lead to dehydration and dry mouth. In the U.S. it’s recommended that men consume 3.7 liters of fluids a day22 and that women consume 2.7 liters. This includes water, other beverages, and water consumed through food. However, some people will require more or less than this recommendation; for example, if you’re unwell, live in a hot or humid climate, or exercise a lot, you may need to drink more. You’ll know you’re drinking enough when you seldom feel thirsty, and your urine is light yellow or colorless.

Tips to Prevent CPAP Dry Mouth 

How to Treat Dry Mouth Caused by Your CPAP Machine 

If your dry mouth persists throughout the day, you can grab a few quick fixes from the store. One option is to chew sugar-free gum, which can help to stimulate salivary flow23. The National Institute of Dental and Craniofacial Research suggests sucking on sugarless hard candies24, ideally citrus, cinnamon, or mint flavors. You should also avoid tobacco and alcohol, and limit your intake of caffeinated drinks as these can all dry out the mouth. 

Over-the-counter remedies25 , including gels or sprays, can act as saliva substitutes. These should contain either xylitol, carboxymethylcellulose, or hydroxyethyl cellulose. You can also buy mouthwash designed for dry mouth; again, look for ones containing xylitol. Sipping water throughout the day or sucking on ice chips26 are also helpful options.

What to Do If Your Dry Mouth from CPAP Persists 

If you have exhausted your options and are still experiencing dry mouth, you should talk to your healthcare provider. They can help rule out other causes of your dry mouth, and if CPAP is the reason why, they may offer a different solution for treating your sleep apnea that doesn’t involve CPAP therapy.

Frequently Asked Questions

Why do I have a dry mouth after using my CPAP machine?

Dry mouth during CPAP therapy can occur from mouth breathing, mask leaks, air leaks, and a lack of humidity, which can all cause a decrease in saliva production.

How do I treat dry mouth from CPAP?

First, check the data from your CPAP machine to see if your mask is leaking. If it is, try adjusting the fit, and if there’s no improvement, speak to your healthcare provider about trying a new style of mask.

If you breathe through your nose but still have your mouth open, you can try using a chin strap to keep your mouth closed. Regularly utilizing your CPAP humidifier could help prevent dryness, as well as staying hydrated. Lastly, if you have nasal congestion that’s causing dry mouth because you can’t breathe through your nose, try to relieve the congestion for easier nasal breathing.

Is a CPAP worth it?

A randomized study27 of 301 people with mild obstructive sleep apnea in the U.K. showed significant improvement in quality of life following three months of CPAP use. Adherence to CPAP is crucial because untreated obstructive sleep apnea28 can lead to extreme fatigue, insomnia, cognitive impairment, anxiety and depression, and problems with cardiac and metabolic health. If you’re struggling to tolerate your CPAP device after making adjustments, speak to your doctor, who may be able to suggest a CPAP alternative.

Lisa Bowman

Lisa Bowman


About Author

Lisa is a content writer for Sleep Advisor, which combines two of her greatest passions – writing and sleeping. She can also be found writing about fitness, sustainability and vegan food.

Combination Sleeper


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