What are the side effects of medications used to treat obsessive-compulsive disorder (OCD), including sertraline (Zoloft), fluoxetine (Prozac), fluvoxamine (Luvox), paroxetine (Paxil), citalopram (Celexa), and clomipramine (Anafranil)?

Side Effects of Medications Used to Treat OCD

The most common side effects of medications used to treat OCD include gastrointestinal issues (dry mouth, constipation, nausea), nervous system effects (somnolence, tremor, dizziness), sexual dysfunction, and weight changes, with clomipramine typically having more adverse effects than SSRIs. 1, 2

Common Side Effects by Medication Class

SSRIs (Sertraline, Fluoxetine, Fluvoxamine, Paroxetine, Citalopram)

• Gastrointestinal effects:

  • Nausea
  • Dry mouth
  • Constipation
  • Diarrhea
  • Dyspepsia
  • Anorexia/decreased appetite

• Nervous system effects:

  • Somnolence/sedation
  • Insomnia (reported in 28% of patients on fluoxetine vs. 22% on placebo) 3
  • Anxiety (reported in 14% of patients on fluoxetine vs. 7% on placebo) 3
  • Tremor
  • Dizziness
  • Headache
  • Nervousness

• Sexual dysfunction:

  • Decreased libido
  • Ejaculatory failure
  • Impotence
  • Anorgasmia

• Other common effects:

  • Weight changes (both gain and loss)
  • Fatigue
  • Sweating
  • Visual changes 1, 3

Clomipramine (Tricyclic Antidepressant)

Clomipramine has similar efficacy to SSRIs but a less favorable side effect profile 1:

• Anticholinergic effects:

  • Dry mouth (reported in 84% of patients vs. 22% on placebo)
  • Constipation
  • Blurred vision
  • Urinary retention

• Cardiovascular effects:

  • Orthostatic hypotension
  • Tachycardia
  • Risk of cardiac conduction abnormalities

• Sexual dysfunction:

  • Ejaculatory failure (42% vs. 2% on placebo)
  • Impotence (20% vs. 3% on placebo)

• Other significant effects:

  • Sedation/somnolence (54% vs. 13% on placebo)
  • Tremor (54% vs. 11% on placebo)
  • Dizziness (54% vs. 14% on placebo)
  • Weight gain
  • Seizures (lowers seizure threshold)
  • Myoclonus 2, 4

Serious Adverse Effects

SSRIs

• Bleeding risk: SSRIs may increase risk of bleeding events, particularly when combined with NSAIDs, aspirin, or anticoagulants 3
• Hyponatremia: Can occur due to SIADH (syndrome of inappropriate antidiuretic hormone secretion), with elderly patients at higher risk 3
• Activation of mania/hypomania: Reported in 0.8% of OCD patients treated with fluoxetine 3
• Serotonin syndrome: Rare but potentially life-threatening, especially when combined with other serotonergic medications 3

Clomipramine

• Seizures: Higher risk compared to SSRIs
• Cardiac arrhythmias: Risk of QT prolongation and other conduction abnormalities
• Serotonin syndrome: Particularly when combined with SSRIs
• Overdose toxicity: More dangerous in overdose than SSRIs 2, 4

Special Considerations

Combination Therapy

When clomipramine and SSRIs are used in combination (sometimes done in treatment-resistant cases), there is increased risk of:

• Seizures
• Heart arrhythmias
• Serotonin syndrome 5

Antipsychotic Augmentation

For treatment-resistant OCD, antipsychotics may be added, bringing additional side effects:

• Weight gain
• Metabolic dysregulation
• Sedation
• Extrapyramidal symptoms 5, 6

Monitoring Recommendations

• Initial period: Monitor for suicidal ideation, particularly in the first months of treatment and following dose adjustments
• Ongoing monitoring: Watch for behavioral activation/agitation, hypomania, and mania
• Antipsychotic augmentation: Regular monitoring of metabolic parameters (weight, lipids, glucose) is essential 1

Management of Common Side Effects

• Insomnia: Consider adding mirtazapine, trazodone, or short-term use of a benzodiazepine (lorazepam) or non-benzodiazepine (zolpidem) 1
• Sexual dysfunction: Dose reduction, drug holidays, or switching to medications with lower rates of sexual side effects
• GI effects: Taking medication with food, temporary dose reduction, or anti-nausea medications

Remember that higher doses of these medications are typically required for OCD compared to depression or anxiety disorders, which may increase the likelihood and severity of side effects 1.