What is the best course of action for a 71-year-old male patient experiencing confusion, taking excessive doses of hydroxyzine (every 6-8 hours instead of every 6 hours as prescribed) for a rash on his right lower leg?

Immediate Management of Hydroxyzine Overdose with Confusion

Immediately discontinue hydroxyzine and switch to a non-sedating second-generation antihistamine for the rash, as this 71-year-old patient is experiencing acute confusion from excessive hydroxyzine dosing (100 mg every 6-8 hours instead of the prescribed 50 mg every 6 hours), which represents a significant overdose in an elderly patient at high risk for CNS toxicity. 1, 2

Immediate Actions

• Stop hydroxyzine immediately - The patient is taking double the prescribed dose (100 mg vs 50 mg) at potentially more frequent intervals, resulting in hypersedation and confusion, which are the most common manifestations of hydroxyzine overdose 2

• Assess for additional overdose complications:

  • Monitor vital signs closely, particularly for hypotension 2
  • Obtain ECG to evaluate for QT prolongation and risk of Torsade de Pointes, which can occur with hydroxyzine overdose 2
  • Evaluate mental status and level of consciousness beyond confusion (stupor, convulsions) 2

• Provide supportive care with frequent monitoring until hydroxyzine clears, as there is no specific antidote 2

Why This Patient Is at Particularly High Risk

Elderly patients are exceptionally vulnerable to hydroxyzine toxicity due to multiple factors 1:

• Older adults are more sensitive to psychomotor impairment from first-generation antihistamines 1
• Increased risk for falls, fractures, and subdural hematomas 1
• Greater susceptibility to anticholinergic effects (urinary retention, constipation, cognitive impairment) 1
• Potential for unrecognized performance impairment even without subjective awareness of drowsiness 1

Appropriate Alternative Treatment for the Rash

Switch to a non-sedating second-generation antihistamine such as cetirizine 10 mg daily, loratadine 10 mg daily, or fexofenadine 1:

• Second-generation antihistamines have minimal or no CNS effects compared to hydroxyzine 1
• Patients should be offered choice of at least two non-sedating options as individual responses vary 1
• These agents are safer in elderly patients and avoid the dangerous sedative and anticholinergic effects 1

Critical Pitfall to Avoid

Do not assume the rash is worsening and requires continued hydroxyzine - Paradoxically, hydroxyzine itself can worsen dermatitis in patients with certain sensitivities, particularly to ethylenediamine derivatives 3, 4, 5. If the rash persists or worsens despite switching antihistamines, consider that hydroxyzine may have been contributing to the skin problem rather than treating it 3, 5.

Additional Considerations

• Evaluate for hepatic or renal impairment, as hydroxyzine should be avoided in severe liver disease due to inappropriate sedation, and doses should be halved in renal impairment 1

• Review all other medications for additional CNS-active substances (sedatives, opioids, antidepressants) that may have enhanced hydroxyzine's effects 1

• Educate the patient and family about proper medication administration and the serious risks of first-generation antihistamines in elderly patients, emphasizing that confusion and cognitive impairment can occur even at therapeutic doses 1

• Monitor for resolution of confusion over 24-48 hours as hydroxyzine has prolonged plasma half-life and end-organ effects that persist longer than plasma levels 1