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SSRIs (sertraline, fluoxetine, escitalopram, paroxetine, citalopram)

Selective serotonin reuptake inhibitor — antidepressant / anxiolytic

Mechanism of action

Block presynaptic reuptake of serotonin (5-HT), increasing synaptic serotonin over weeks. Used for major depression, generalized anxiety, panic disorder, OCD, PTSD, social anxiety, premenstrual dysphoric disorder, and bulimia nervosa. First-line antidepressants because of favorable safety profile vs TCAs and MAOIs.

Adverse effects

Life-threatening / NCLEX-tested

  • Suicidality risk increase in the first few weeks, especially in patients < 25 — boxed warning; monitor closely after start and dose changes
  • Serotonin syndrome — life-threatening when combined with other serotonergic agents (triad: autonomic instability, neuromuscular hyperactivity, mental status changes; clonus and hyperreflexia)
  • Hyponatremia (SIADH), especially in older adults
  • Bleeding risk (platelet 5-HT depletion) — additive with NSAIDs, anticoagulants, antiplatelets
  • QT prolongation (citalopram > 40 mg/day, escitalopram > 20)
  • Withdrawal/discontinuation syndrome — flu-like, dizziness, electric-shock sensations; taper slowly
  • Weight changes (can be loss or gain)

Side effects

Common — what to teach

  • GI upset, nausea (often improves in 1–2 weeks)
  • Sexual dysfunction (decreased libido, anorgasmia, ED) — common reason for non-adherence
  • Insomnia or somnolence
  • Headache
  • Dry mouth
  • Sweating, mild tremor

Food & drug interactions

MAOIs are an ABSOLUTE contraindication — wait at least 14 days between MAOI and SSRI (5 weeks for fluoxetine due to long half-life). Triptans, tramadol, fentanyl, linezolid, St. John's wort, and other antidepressants compound serotonin syndrome risk. NSAIDs and anticoagulants raise bleeding risk. Many SSRIs are CYP2D6 inhibitors (paroxetine, fluoxetine) — affect tamoxifen efficacy and others. Alcohol amplifies CNS effects.

Nursing implications

Assessment, monitoring, patient teaching

  • Counsel that mood improvement takes 4–6 weeks; physical symptoms (sleep, appetite, energy) often improve first
  • Suicide risk monitoring — especially in first 1–4 weeks, dose changes, and patients < 25; involve family/safety plan
  • Teach serotonin-syndrome warning signs — agitation, confusion, sweating, tremor, twitching, fever, fast HR — STOP and seek emergency care
  • Reinforce ADHERENCE — never stop abruptly; taper over weeks
  • Counsel about sexual side effects up front so patients are not surprised; alternatives (bupropion, mirtazapine) exist if disabling
  • Reconcile NSAID, anticoagulant, antiplatelet use — bleeding risk additive
  • Monitor BMP for hyponatremia in older adults

When to hold / contraindications

  • MAOI within 14 days (5 weeks for fluoxetine)
  • Suspected serotonin syndrome — discontinue and supportive care
  • Severe hyponatremia
  • QTc > 500 ms or active arrhythmia (citalopram especially)
  • Active suicidal crisis without safety plan and team involvement
  • Severe bleeding

Memory anchor

SSRIs end in "-pram, -line, -ine, or -etine." "Takes weeks, can't stop cold, can't combine with MAOI." Watch for serotonin syndrome and suicide risk early.

Reminder: Drug cards are study aids, not clinical guidance. Always cross-check doses, holds, and contraindications with your facility's formulary and your clinical instructors before patient care.

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