Abuse potential. Useful medication for pain patients who are tolerant to other more common opiates. Downsides include potential for chemical dependence, withdrawal symptoms on discontinuation, high abuse potential. Some may get itching and nausea, this is not uncommon with any opioid preparation however.
See below. Actiq is an excellent treatment for breakthrough pain when a patient is taking an around the clock opioid medication for chronic pain. Some downsides to Actiq are the length of time it takes to work, the length of time needed to get the full effect, the dental side effects of the sugar, the need to continuously rub it again one's cheek.