anesthesia
"I had my first colonoscopy yesterday and was given Propofol and Zofran.  I believe some people can have an allergic reaction to Propofol which is what I experienced. 

Right after the procedure, my nose was really itchy and I sneezed several times. It continued with a runny nose and lasted several hours.  I took DayQuil when I got home and it didn't stop the symptoms so 2 hours later, I took a generic Antihistamine and that stopped it.  I woke up this morning without a runny nose or sneezing."