 [ Symptoms ] what is respiratory tract infection [ Disease ] most helpful answer thanks for giving such great detail in your post it is very helpful of course i can not diagnose you by internet i can not diagnose you at all legally but here is my take on the situation although your cpap is humidified the bright red blood you are seeing probably is in fact due to your airway becoming dehydrated from the air flow during sleep generally speaking bright red blood in a body substance mucus stool is not really in the substance    it is on it and when blood is on another body fluid it means it originated elsewhere such as from torn tissue i wish i could offer you some advice about how to resolve the situation you might try lubricating your nasal passages with a small amount of water based lubricant like k y jelly not petroleum jelly or lotion or anything like that to see if it helps a small amount of k y jelly rubbed just inside the nostrils before bed often solves issues like minor nosebleeds and even tissue dehydration from a cpap i know you said you are a mouth breather but you still might give it a whirl if the situation does not clear up within a couple of weeks definitely check with your healthcare provider about it many people discontinue the use of cpap machines for reasons such as the one you are describing and that is not good if you have sleep apnea you definitely need to continue using your cpap while it may be unrealistic to aim for complete comfort with zero side effects from using the cpap your provider may be able to help you find a way to be comfortable while using this life saving device wishing you well