“Opioid-induced anxiety” refers to a state of anxiety that develops as a side effect of taking opioid medications, where prolonged opioid use can trigger or worsen anxiety symptoms like panic attacks, obsessive thoughts, restlessness, and increased heart rate, often occurring when the drug wears off due to the body’s response to the sudden drop in neurotransmitter levels; it can also manifest as a withdrawal symptom when someone stops taking opioids.