Can Trazodone Cause Urinary Retention?
Yes, trazodone can cause urinary retention, though it is relatively uncommon compared to other psychotropic medications, and elderly patients with benign prostatic hyperplasia or those on multiple anticholinergic medications face substantially elevated risk. 1
Evidence from FDA Labeling
The FDA-approved drug label for trazodone explicitly lists urinary retention as a post-marketing adverse reaction, along with delayed urine flow reported in clinical trials at <2% incidence. 1 The label also documents urinary incontinence as a post-marketing adverse event, indicating trazodone affects urinary function bidirectionally. 1
Mechanism and Risk Profile
Trazodone's anticholinergic properties, though weaker than tricyclic antidepressants, can impair bladder contraction and contribute to urinary retention. 2, 3 The drug causes failure of bladder contraction through anticholinergic mechanisms, similar to other psychotropic agents. 3
High-Risk Populations
Elderly patients are at substantially elevated risk due to:
- Pre-existing benign prostatic hyperplasia (the most common cause of baseline urinary retention) 4
- Polypharmacy with multiple anticholinergic medications 5
- Compromised autonomic function 5
- Cognitive impairment affecting recognition of symptoms 5
Men are more vulnerable than women because prostatic enlargement creates a baseline obstruction that anticholinergic drugs can precipitate into acute retention. 3
Comparative Risk Among Psychotropics
While trazodone can cause urinary retention, the systematic review evidence shows varying rates across antidepressant classes:
- Tricyclic antidepressants (imipramine): 17.6% incidence 6
- All tricyclics analyzed together: 0.1% incidence 6
- Selective serotonin reuptake inhibitors: 0.025% incidence 6
- Duloxetine (SNRI): 0% in 1,139 patients 6
Trazodone's risk appears lower than traditional tricyclics but the FDA label confirms it occurs. 1
Clinical Monitoring and Prevention
For high-risk patients starting trazodone, the European Urology Association recommends:
- Baseline assessment measuring electrolytes, BUN, creatinine, and documenting urinary symptoms 5
- Measuring post-void residual if available 5
- Early monitoring every 2-3 days for 1-2 weeks after initiation 5
- Assessing for decreased urinary output, suprapubic discomfort, or changes in voiding pattern 5
Prevention strategies include:
- Avoiding combining multiple anticholinergic agents 5
- Considering alternative antidepressants with lower anticholinergic profiles in patients with benign prostatic hyperplasia 5
- Regular medication list review to identify drug-drug interactions 5
Management When Retention Occurs
If urinary retention develops on trazodone:
- Acute management requires bladder catheterization for immediate relief 7
- Discontinuation or dose reduction of trazodone typically results in improvement, as documented in the majority of case reports 6
- Rule out other causes including fecal impaction, restricted mobility, and urinary tract infections 5
The American Geriatrics Society emphasizes addressing reversible causes and reviewing the entire medication regimen when urinary retention occurs. 5
Critical Caveats
The possibility of acute urinary retention caused by trazodone, particularly in older males with benign prostatic hyperplasia, cannot be ignored. 8 A recent case report documented mirtazapine (another antidepressant with anticholinergic properties) causing acute urinary retention the day after initiation in a 70-year-old man with benign prostatic hyperplasia, illustrating how quickly this adverse effect can manifest in vulnerable patients. 8
Up to 10% of acute urinary retention episodes may be attributable to concomitant medication use. 2 The European Heart Journal guidelines classify antiarrhythmic drugs with anticholinergic effects (class IA) as causing urinary retention, dry mouth, and constipation, reinforcing that any medication with anticholinergic properties poses this risk. 9