What is the most likely explanation for the patient's nausea and vomiting after buprenorphine/naloxone induction with a COWS score of 5?

The patient's nausea and vomiting following buprenorphine/naloxone induction, combined with a Clinical Opioid Withdrawal Scale (COWS) score of 5, points toward precipitated opioid withdrawal as the most likely reason for these symptoms. When buprenorphine is administered to someone who is not in full withdrawal, or who has short-acting opioids still active in their system, it can displace those opioids from the receptors. This rapid change can trigger withdrawal symptoms to emerge infamously, as the patient experiences a sudden drop in the opioid effects they were previously receiving.

The COWS score of 5 indicates mild withdrawal symptoms, suggesting that the patient is entering the withdrawal phase but was not adequately prepared for the induction of buprenorphine. The rapid onset of nausea and vomiting along with other withdrawal symptoms can indicate that the patient’s body is reacting negatively to the abrupt shift in opioid levels, rather than indicating that withdrawal symptoms were too severe or that a separate condition, such as pancreatitis or alcohol withdrawal, is responsible for these reactions. Thus, the context of the treatment and the circumstances of opioid use support the likelihood of precipitated withdrawal.