Dicyclomine-Induced Acute Urinary Retention in a Patient With Benign Prostatic Hyperplasia

Patient Background

Mr. Jim H. is a 68-year-old retired teacher with a medical history of irritable bowel syndrome (IBS), benign prostatic hyperplasia (BPH), hypertension, hyperlipidemia, and gastroesophageal reflux disease (GERD). His long-standing BPH had been well controlled with tamsulosin 0.4 mg once daily, and he reported only mild urinary hesitancy without significant lower urinary tract symptoms.

His regular medications included lisinopril 20 mg daily, atorvastatin 20 mg nightly, tamsulosin 0.4 mg daily, and omeprazole 20 mg daily.

Clinical Presentation

Mr. Jim presented to his primary care provider with progressively worsening intermittent lower abdominal cramping occurring over several months. The pain was most pronounced after meals and typically improved following bowel movements. He denied weight loss, rectal bleeding, fever, or other alarm symptoms. Based on his history of IBS and the absence of concerning gastrointestinal features, dicyclomine 20 mg four times dailywas prescribed to relieve intestinal smooth muscle spasm.

Within the first week of therapy, Mr. Jim experienced significant improvement in abdominal pain, allowing him to eat comfortably and resume normal daily activities. Approximately two weeks later, however, he developed progressively worsening urinary hesitancy, a weak urinary stream, and a persistent sensation of incomplete bladder emptying. He also reported increasing nocturia, although only small volumes of urine were passed.

One evening, he developed severe suprapubic pain and was unable to void for nearly 12 hours. He presented to the emergency department, where physical examination revealed a markedly distended and tender bladder. Bedside bladder ultrasonography demonstrated more than 900 mL of retained urine, confirming acute urinary retention. A urinary catheter was inserted, immediately draining a large volume of urine and providing rapid symptom relief.

Clinical Issue Identified

During medication reconciliation, the emergency physician and clinical pharmacist identified the recent initiation of dicyclomine as the most likely precipitating factor for the patient’s acute urinary retention. Dicyclomine is a potent antimuscarinic (anticholinergic) agent that reduces gastrointestinal smooth muscle spasm by inhibiting muscarinic receptor activity. However, the same pharmacologic action also reduces detrusor muscle contractility, impairing bladder emptying.

In patients with benign prostatic hyperplasia, bladder outlet obstruction already increases resistance to urine flow. The additional reduction in bladder contractility produced by anticholinergic therapy can overwhelm compensatory mechanisms, resulting in acute urinary retention, a recognized complication of antimuscarinic medications. The close temporal relationship between initiation of dicyclomine and the onset of urinary symptoms strongly supported a medication-induced adverse effect.

Pharmacist Intervention and Clinical Management

Identification of the Drug-Induced Adverse Effect

• Recognize dicyclomine as the likely cause of acute urinary retention.
• Correlate the onset of urinary symptoms with recent initiation of anticholinergic therapy.

Immediate Therapeutic Intervention

• Discontinue dicyclomine immediately.
• Continue bladder decompression with urinary catheterization until adequate bladder function returns.
• Maintain tamsulosin therapy to optimize bladder outlet relaxation.

Alternative Management of Irritable Bowel Syndrome

• Reassess the need for pharmacologic antispasmodic therapy.
• Consider non-anticholinergic management strategies, including:
  • Dietary modification (e.g., low-FODMAP diet) FODMAP
  • Soluble fibre supplementation where appropriatem
  • Peppermint oil
  • Gut-directed behavioural interventions
• If pharmacotherapy remains necessary, select agents with minimal anticholinergic activity whenever possible.

Monitoring and Follow-Up

• Perform a trial without catheter once urinary function has recovered.
• Monitor for recurrence of urinary symptoms following discontinuation of dicyclomine.
• Reassess IBS symptom control and quality of life.

Patient Education

• Counsel the patient regarding medications that possess anticholinergic properties and their potential to worsen urinary symptoms.
• Encourage prompt medical review if future urinary hesitancy, inability to void, or suprapubic discomfort develops.
• Advise the patient to inform healthcare providers of his history of BPH before starting new medications.

Clinical Rationale and Ramifications

This case illustrates the importance of considering underlying disease states before initiating medications with anticholinergic properties. Although dicyclomine effectively relieved Mr. H.’s gastrointestinal symptoms, its pharmacologic effects on the urinary bladder precipitated acute urinary retention in the setting of pre-existing bladder outlet obstruction due to BPH.

Failure to recognize this contraindication resulted in emergency department presentation, urinary catheterization, acute patient discomfort, and avoidable healthcare utilization. Importantly, the patient’s urinary function returned to baseline following withdrawal of the offending medication, confirming the diagnosis of medication-induced urinary retention.

This case reinforces the critical role of comprehensive medication review and individualized prescribing, particularly in older adults with multiple comorbidities. Before prescribing anticholinergic medications, clinicians should carefully evaluate pre-existing conditions such as benign prostatic hyperplasia, glaucoma, constipation, and cognitive impairment, as these conditions substantially increase the risk of serious adverse effects. Careful therapeutic selection can prevent avoidable complications while maintaining effective symptom control.