Yes, Bentyl (dicyclomine) can absolutely cause increased confusion and agitation in elderly males and should be avoided in this population.
Direct Evidence from FDA Drug Label
The FDA drug label for Bentyl explicitly warns that "CNS signs and symptoms include confusion, disorientation, short-term memory loss, hallucinations, dysarthria, ataxia, coma, euphoria, decreased anxiety, fatigue, insomnia, agitation and mannerisms, and inappropriate affect" in sensitive individuals given anticholinergic drugs 1. The label further states that "Psychosis has been reported in sensitive individuals given anticholinergic drugs" 1.
Why This Occurs: Anticholinergic Mechanism
Dicyclomine is a strongly anticholinergic medication that blocks muscarinic receptors throughout the body 1. In elderly males, this anticholinergic burden is particularly dangerous because aging is already associated with declining acetylcholine physiology 2. When anticholinergics like dicyclomine are added, they further block already-diminished acetylcholine activity, resulting in:
- Cognitive impairment and confusion
- Delirium episodes
- Paradoxical agitation
- Functional decline
- Increased fall risk
- Emergency department visits and hospitalizations 2
Clinical Guidelines Position
The 2021 Mayo Clinic polypharmacy guidelines specifically identify strongly anticholinergic medications—including muscle relaxants like cyclobenzaprine and overactive bladder agents like oxybutynin—as high-risk drugs that should be deprescribed in older adults 2. While dicyclomine isn't explicitly named in these examples, it shares the same strong anticholinergic properties and mechanism of harm.
The guidelines emphasize that "anticholinergic medications are usually poorly tolerated in aged patients" and that "patients taking multiple anticholinergic drugs, dubbed 'anticholinergic burden,' often adversely affects cognition and functionality" 2.
Specific Risks in Elderly Males
Elderly males face compounded risks:
- Cognitive effects: Confusion, disorientation, short-term memory loss, and delirium 1
- Behavioral effects: Agitation, paradoxical agitation, anxiety, and inappropriate affect 1, 3
- Urinary retention: Particularly problematic in elderly males with prostatic hypertrophy 2
- Falls: Increased risk due to dizziness, sedation, and impaired coordination 2
- Functional decline: Decreased activities of daily living scores 2
Time Course and Reversibility
The good news is that these CNS signs and symptoms usually resolve within 12 to 24 hours after discontinuation of the drug 1. This makes dicyclomine a prime candidate for immediate discontinuation if confusion or agitation develops.
Clinical Decision Algorithm
When an elderly male presents with confusion or agitation while taking dicyclomine:
- Immediately discontinue dicyclomine - symptoms typically resolve in 12-24 hours 1
- Assess for other anticholinergic medications - calculate total anticholinergic burden 2
- Monitor for symptom resolution over the next 24 hours
- If IBS symptoms require treatment, consider non-anticholinergic alternatives
- Do not restart dicyclomine - the elderly patient has demonstrated sensitivity
Common Pitfall to Avoid
Do not attribute new-onset confusion or agitation in an elderly patient to "just dementia" or "sundowning" without first reviewing their medication list for anticholinergic agents like dicyclomine. Drug-induced confusion is a reversible cause that must be identified and addressed 4, 5.