Can Selective Serotonin Reuptake Inhibitors (SSRIs) cause tremors?

Do SSRIs Cause Tremors?

Yes, SSRIs commonly cause tremor as a dose-related adverse effect, with tremor recognized as a typical side effect across this entire drug class. 1, 2

Mechanism and Clinical Presentation

SSRIs cause tremor through excessive serotonergic activity in the central nervous system, typically manifesting as enhancement of physiological tremor. 2, 3 The tremor is dose-dependent, meaning higher doses carry greater risk of this adverse effect. 1, 2

Specific SSRI Agents

All SSRIs in the class can cause tremor, including:

• Fluoxetine - FDA labeling documents tremor as a recognized adverse effect, particularly in neonates exposed during pregnancy who develop tremor, jitteriness, and hypertonia. 4
• Sertraline - Tremor is a commonly reported adverse effect at therapeutic doses, typically mild to moderate in severity. 5, 6
• Paroxetine - Causes tremor with similar frequency to other SSRIs, though it is more anticholinergic than other agents in the class. 1
• Citalopram and escitalopram - Both cause tremor, with neonatal exposure resulting in tremors that typically resolve within 1-4 weeks. 2
• Fluvoxamine - Causes tremor as part of the typical SSRI side effect profile. 1

Risk Factors for SSRI-Induced Tremor

Polypharmacy, older age, and high doses significantly increase the risk of developing tremor on SSRIs. 5 Additional risk factors include:

• Rapid dose escalation or inadequate up-titration 1, 2
• Younger children (more susceptible than adolescents) 1
• Concomitant use of other serotonergic medications 1, 2
• Reduced hepatic function (as SSRIs are hepatically metabolized) 7

Critical Distinction: Benign Tremor vs. Serotonin Syndrome

You must distinguish between isolated SSRI-induced tremor and serotonin syndrome, which requires immediate hospitalization. 1, 5

Isolated SSRI Tremor

• Tremor occurs alone or with mild symptoms (sweating, nervousness, insomnia) 1
• No mental status changes 1
• No autonomic instability 1
• Typically appears early in treatment or with dose increases 1, 2

Serotonin Syndrome (Medical Emergency)

• Tremor accompanied by mental status changes (confusion, agitation, anxiety) 1
• Neuromuscular hyperactivity (clonus, hyperreflexia, muscle rigidity) 1
• Autonomic hyperactivity (hypertension, tachycardia, diaphoresis, hyperthermia) 1
• Symptoms arise within 24-48 hours after combining serotonergic medications 1
• Advanced symptoms include fever, seizures, arrhythmias, and unconsciousness 1
• Requires discontinuation of all serotonergic agents and hospital-based supportive care with continuous cardiac monitoring 1

Management of SSRI-Induced Tremor

For Isolated Tremor

If tremor is isolated and mild, reduce the SSRI dose or slow the up-titration schedule, particularly in younger children. 1, 2, 5 Specific strategies include:

• Decrease the current dose 5
• Implement slower dose escalation (give the second daily dose before 3 PM for activating SSRIs to minimize insomnia) 1
• Provide reassurance with continued monitoring if tremor is tolerable 5
• Consider switching to a different SSRI if tremor persists despite dose reduction 1

For Suspected Serotonin Syndrome

Immediately discontinue all serotonergic medications and transfer to hospital for continuous cardiac monitoring and supportive care. 1, 5

Prevention Strategies

When combining SSRIs with other serotonergic drugs, start the second agent at a low dose, increase slowly, and monitor intensively in the first 24-48 hours after any dosage change. 1, 2 Avoid combining SSRIs with:

• MAO inhibitors (phenelzine, isocarboxazid, linezolid) - absolute contraindication 1, 2
• Other antidepressants (SNRIs, TCAs, atypical antidepressants) 1
• Opioids (tramadol, meperidine, methadone, fentanyl) 1, 2
• Stimulants (amphetamines, possibly methylphenidate) 1
• Over-the-counter medications (dextromethorphan, St. John's wort, L-tryptophan) 1

Common Pitfall

Approximately 63% of patients on SSRIs experience at least one adverse effect, with tremor being commonly reported. 2 Failing to recognize this high baseline rate leads to under-recognition of SSRI-induced tremor and missed opportunities for dose adjustment. 2

Resolution Timeline

Drug-induced tremor from SSRIs typically resolves after discontinuation of the medication, though persistent tremor can rarely occur (tardive tremor). 5, 8 Behavioral activation and isolated tremor usually improve quickly after SSRI dose decrease or discontinuation. 1