I have had the worst diahrrea with ultracet. It is a wonder I haven't accidently killed myself with this. I'd get the diahrrea and take an OTC remedy for it while not realizing the diahrrea was from the ultracet. I'd sleep for about 3 hours at a time, wake up for 30 minutes, and struggle to go back to sleep. I was wondering why it did nothing for my pain and then found out it is an opiate derivative. I'm one of those not susceptible to opiates for pain relief. However, when given an opiate I do hallucinate. No wonder I was seeing spiders. I'm going to ride out the withdrawal and see what happens. Wish me luck.