DISEASE CHARACTERISTICS: Complaint of dry mouth with ALL the following characteristics: At least 1 week in duration Attributed by the treating physician to an opioid Severity rating at least 20 mm on a 100 mm visual analog scale Must be receiving routine (i.e., not just as needed) dosing with one of the following opioids: morphine, hydromorphone, transdermal fentanyl, methadone, or oxycodone Intent to continue opioid therapy at the same or higher dose over the first 2 weeks that the patient is receiving protocol treatment