We make "neb cup soup" almost everyday by boiling for at least 10 minutes. After boiling we shake them off well, hang them on a bottle rack for 10-15 minutes until completely dry, then into an airtight container they go. Oh yes, setting the timer is a must for us bc neb cups do melt!
We have several cups in the rotation so that we don't have to do this everyday, although we usually do. I was washing in them in the dishwasher occassionally on Sanicycle but I realized that our Sanicycle only gets to like 145 degrees and CFF says dishwasher needs to be over 158 degrees so I don't do that anymore. Boiling is just as easy anyway.
Here is the CFF document on cleaning nebs:
<a target=_blank class=ftalternatingbarlinklarge href="http://www.cff.org/UploadedFiles/LivingWithCF/StayingHealthy/Germs/StoppingTheSpread/StoppingSpreadGerms.pdf">http://www.cff.org/UploadedFil...toppingSpreadGerms.pdf</a>