A 45-year-old client who has taken paroxetine 40 mg daily for 3 years stopped the medication abruptly 3 days ago because the bottle was lost. The client now reports flu-like fatigue, dizziness, lightning-like sensations called "brain zaps," nausea, vivid dreams, irritability, and trouble sleeping. Which is the priority nursing action?

SSRI/SNRI discontinuation syndrome arises when a serotonergic antidepressant is stopped abruptly or tapered too quickly after at least 4 to 6 weeks of use. Risk is highest with short-half-life agents (paroxetine, venlafaxine, duloxetine) and very high chronic doses; lowest with fluoxetine because of its long active metabolite. Onset 1 to 3 days after stopping; resolves spontaneously over 1 to 3 weeks. Mnemonic FINISH: Flu-like, Insomnia, Nausea, Imbalance/dizziness, Sensory disturbances ("brain zaps"), Hyperarousal/agitation. Distinguishing from depression relapse: discontinuation syndrome has somatic dominance, comes within days, resolves rapidly with restarting; depression relapse takes weeks and lacks the sensory/somatic features. Standard nursing response: (1) recognize and contact prescriber; (2) restart paroxetine at the previous dose with rapid symptom resolution, then taper gradually over weeks (often 5 mg every 1 to 2 weeks); alternative is to switch to fluoxetine for a few days to bridge, then taper because fluoxetine self-tapers; (3) reassure that this is not relapse and is reversible, but screen for true depression separately; (4) educate to never stop abruptly and to plan tapers; (5) symptomatic relief — rest, hydration, brief antiemetic if needed. Reassuring without action, indefinite cessation, and adding SSRI are wrong.

Discontinuation syndrome appears within days of abrupt SSRI stop, especially paroxetine. Restart and taper slowly. Differentiate from relapse.