Question:

I have been using a CPAP machine with a humidifier since mid-June 2007. I have been experiencing a persistent dry cough during the day, but especially during the night. It wakes me up several times a night. Coughing does not relieve the tickle in my throat. I have been taking Flonase with no improvement. I thought it might be a side effect of Cozaar. But the other night I did not use my CPAP machine and had NO coughing for 24 hours. I went without the CPAP last night too–again with no coughing. I carefully clean and sterilize all the tubing and humidifier, so I doubt it is mold/fungus in the machine. Could I be allergic to the silicone nasal pillows or plastic tubing and humidifier? Thank you for any help you can offer.

Answer:

There are a number of causes of chronic cough, of which chronic bronchitis (especially in smokers), asthma, post-nasal drip and heartburn (or gastroesophageal reflux) are the most common. Sleep apnea by itself has not been found to be a frequent cause of chronic cough, though when the airway collapses in sleep, individuals may awaken with a choking and coughing spell as the airway reopens during an arousal from sleep. Treatment of sleep apnea with CPAP keeps the airway open during sleep and thus prevents the repetitive choking and coughing that occurs in some individuals.

In your case, your sleep apnea has been treated with CPAP with a humidifier, but you have been experiencing a cough with this. It is not clear from the question if the cough started before or after you began using the CPAP. Assuming it started after you began using the CPAP, then it is reasonable to be concerned that the cough could be related to the treatment. Possible ways in which use of CPAP could lead to coughing include: an increase in nasal congestion with post-nasal drip (though you point out you have been using flonase with no help), nasal and mucosal drying due to the inhalation of dry cool air (though you point out you have a humidifier with the CPAP), an allergic reaction to components of the CPAP device or mask, irritation of airway receptors due to high airway pressures, or infection related to worsening of an underlying sinus condition or contaminated water in the humidifier

It is reasonable to make sure that your humidifier is heated (and if not, to get a heated humidifier) and speak to your Sleep Physician about the problem. It’s possible that you could be allergic to some component of the CPAP mask and changing your interface may be needed. Cozaar, which can lead to coughing to some individuals, should also be considered as a potential cause in your case. Of course, specific factors in your history may suggest other diagnoses that require specific testing, so talking to your doctor would be a good idea.

To learn more about sleep apnea or other sleep disorders, please visit the American Academy of Sleep Medicine website. In addition to information, the website contains a list of Sleep Centers across the country so that you may locate one near you. The American Sleep Apnea Association also has some information at their website that you might find useful.

For more information:

Go to the Sleep Disorders health topic.