Acute withdrawal syndrome: This is a syndrome of dramatic and severe physical and psychological symptoms following opioid cessation or dose decrease in a patient dependent on opioids that is self-limiting (7-10 days). The symptoms include anxiety, agitation, runny nose, sweating, yawning, abdominal cramping and diarrhea, nausea, vomiting, increased diffuse pain, hyperalgesia, and overall severe distress.