An adult on paroxetine experiences dizziness and electric shock sensations after stopping the medication abruptly. The most likely explanation is?

• A. Serotonin syndrome
• B. Paroxetine withdrawal reaction
• C. Depression relapse
• D. Anxiety relapse

Answer: (B)

Discontinuation (withdrawal) symptoms from stopping an SSRI abruptly. When paroxetine is taken regularly, the brain adapts to higher serotonin activity; stopping suddenly causes a rapid drop in serotonergic signaling, leading to dizziness and electric shock–like sensations (often described as brain zaps). Paroxetine’s short half-life makes these withdrawal symptoms more likely and usually more noticeable, especially after abrupt cessation. This pattern is distinct from serotonin syndrome, which involves excessive serotonin and presents with autonomic instability, tremor, confusion, and hyperthermia, not just post-stop dizziness and brain zap sensations. Relapse of depression or anxiety tends to manifest as mood or anxiety symptoms rather than the characteristic discontinuation sensations. To reduce risk, taper the dose gradually rather than stopping abruptly; if withdrawal occurs, restarting and tapering more slowly or switching to a longer-acting agent before tapering can help.