Opioid withdrawal presenting only nausea during tapering of oxycodone after celiac plexus block: a case report.

Celiac plexus block (CPB) is an effective treatment for patients suffering pain. CPB may allow for a reduction in opioid dosage, and may alleviate some of the unwanted side effects of these drugs. However, there is a substantial risk of withdrawal symptoms after reduction of opioid dose. We describe a case of pancreatic cancer developing opioid withdrawal after CPB, who presented only nausea. A 70-year-old man was referred to our hospital due to severe pancreatic cancer pain. He was administered oxycodone (oxycontin®) at 240 mg per day, and presented nausea and anorexia as side effects. CPB was performed due to insufficient pain relief. His pain disappeared on the same day as treatment. Oxycodone was reduced to 160 mg/day, and further reduced two days later to 80 mg/day. However, he complained of more severe nausea and loss of appetite even after tapering of oxycodone. Physical examination, blood chemistry examination, and brain computed tomography (CT) showed no abnormalities. Administration of fast-release oxycodone (Oxinome®) at a dose of 10 mg immediately improved his nausea. There have been no previous reports of nausea as the sole symptom of opioid withdrawal. The present case indicates that unless opioid side effects improve after dosage reduction, the possibility that they may be withdrawal symptoms should also be considered.