You MUST keep them clean or at least sterilize it with boiling water before you start using it again. You can also microwave the thing with water in it for 3 mins and its good to go for a week of use. PLEASE be sure to use the salt packages. Plain tap water HURTS! you will not want to use it again.

I swear by mine! it has saved me from antibiotics several times as it flushes out all the bacteria, mucous and phlegm. I can breathe again! cheap and cheerful.