Yes, Prozac (fluoxetine) can cause shaking or tremor as a recognized side effect.
Tremor is a commonly reported adverse effect of fluoxetine and other SSRIs, occurring in approximately 63% of patients who experience at least one side effect during treatment with second-generation antidepressants 1.
Clinical Features of Fluoxetine-Induced Tremor
The tremor associated with fluoxetine has specific characteristics:
- Type: Predominantly postural tremor (statistically significant compared to rest tremor, p<0.0005) 2
- Frequency: Ranges from 6-12 Hz 2
- Severity: Generally mild 2
- Onset: Average latency of 54 days after starting treatment 2
- Dose: Can occur at relatively low doses (mean 25.7 mg/day in one cohort) 2
Important Clinical Considerations
Persistence After Discontinuation
A critical caveat: In approximately half of patients who develop fluoxetine-induced tremor, the tremor may persist even after discontinuing the medication. In one study, tremor resolved in only 10 of 21 patients after stopping fluoxetine (mean resolution time 35.5 days), while the remaining 11 patients had persistent tremor for an average of 449 days 2.
Comparative Risk Among Antidepressants
Fluoxetine carries a higher risk of activating side effects, including tremor, compared to tricyclic antidepressants 3. Among SSRIs, fluoxetine is associated with more tremor compared to some alternatives, with paroxetine, imipramine, and fluoxetine showing significantly higher risk of extrapyramidal symptoms (including tremor) compared to citalopram 4.
Risk Factors
Patients at higher risk for developing tremor include those with:
- History of tremor (HR: 7.4, p=0.002) 4
- Prior antipsychotic use (HR: 3.9, p=0.001) 4
- Older age 4
- Smoking history (HR: 1.7, p=0.02) 4
Overdose Context
In overdose situations, tremor is one of the more common presenting symptoms 5, and can be part of serotonin syndrome, which includes tremor, diarrhea, delirium, neuromuscular rigidity, and hyperthermia 1, 6.
Clinical Management Implications
When prescribing fluoxetine, specifically counsel patients about tremor as a potential side effect, particularly if they have risk factors. The FDA label for Prozac lists tremor among panic disorder symptoms but acknowledges it as a recognized adverse effect 6. Given the potential for persistent tremor even after discontinuation, consider alternative SSRIs (such as citalopram or sertraline) in patients where tremor would be particularly problematic or in those with pre-existing tremor history.