I was so excited about getting Invisalign braces and began my 1st tray of 23 in January 2012. Shortly thereafter, I started getting a bad cough and my lips were sore. Because I had pnemonia a couple of months previously I thought that I was having another episode. I mentioned to my dentist several times that I had this bad cough and was wondering if they had heard if this was a side effect of the Invisalign. He said that he hadn't heard of that ever happening. I proceeded to have numerous doctors appointments, an unexpected trip to the emergency room and later a visit to a pulmonologist. For many months and nights I slept in a chair because when I laid down the coughing was unbearable. I lived on Tussinex (codine) for months on end, just to be able to sleep. After all was said and done and the process of elimation was done, I found out I was allergic to my Invisalign's. I went back to my dentist and they ordered hypo-allergetic ones. At this point I was on tray 20. Due to all the set backs and waiting on the new ones I ended up losing 2 months of time. Things from then on seemed to be going along smoothly until I had a tray that didn't fit. It was ascertained that I needed new impressions and they sent them to Invisalign so that new trays could be made. When they came back, I had 17 new trays!!! In other words, 37 trays instead of the initial 23. After several weeks with the new trays I started coughing again. I brought this up with the dentist office and they found out that Invisalign had made the new trays with the hypo-allergetic material but did not make them in a sterile environment so they were getting contaminated hence my allergic reaction. At this point I told my dentist that straight teeth were no longer my objective but being healthy was. The allergic reaction from all of this brought on asthma and I'm slowly trying to ween myself off an inhaler that cost $50 per month. I don't think straight teeth or the months I've spent was worth injury to my health. By the way, make sure that you and your dental office rinses off the trays before they said they come with a residue on them that some people may have issue with.