What is the next best step for a 91-year-old patient with generalized itching and welts who has not responded to Allegra (fexofenadine)?

Evaluation and Management of Generalized Itching and Welts in a 91-Year-Old Unresponsive to Fexofenadine

In a 91-year-old patient with generalized itching and welts (urticaria) who has not responded to fexofenadine (Allegra), the next best step is to add an H2 antihistamine such as cimetidine or famotidine to the current H1 blocker, while simultaneously initiating emollients and topical corticosteroids for at least 2 weeks to exclude asteatotic eczema, which is common in elderly patients. 1

Initial Reassessment and Diagnostic Considerations

Before escalating therapy, ensure proper investigation has been completed, as generalized pruritus has a significant underlying systemic cause in 20-30% of cases 1:

• Order baseline laboratory investigations including ferritin, complete blood count, renal function (urea and electrolytes), liver function tests, and erythrocyte sedimentation rate 1
• Consider chest X-ray to evaluate for underlying malignancy 1
• Evaluate for bullous pemphigoid, which can present with pruritus alone in elderly patients before blistering appears—consider skin biopsy and indirect immunofluorescence if clinical suspicion exists 1
• Review medication list for drug-induced pruritus, particularly opioids, which are common culprits 1

Immediate Therapeutic Interventions

First-Line Adjustments for Elderly Patients

Start emollients with high lipid content and moderate-potency topical corticosteroids (clobetasone butyrate) for at least 2 weeks to treat potential asteatotic eczema, which is extremely common in patients over 65 years 1:

• This addresses the most common cause of pruritus in the elderly population 1
• Topical menthol preparations may provide additional symptomatic relief 1
• Topical doxepin can be considered but should be limited to 8 days, 10% body surface area, and 12 grams daily 1

Systemic Therapy Escalation

Add an H2 antihistamine (famotidine or cimetidine) to the existing fexofenadine regimen 1:

• The combination of H1 and H2 antagonists provides better control than H1 blockers alone 1
• Note that ranitidine was previously used but has been withdrawn from many markets 1
• Important caveat: H2 antihistamines with anticholinergic effects can contribute to cognitive decline in elderly patients, so monitor closely 1

Consider increasing the fexofenadine dose to 180 mg daily if not already at this level 1:

• Fexofenadine can be safely used at 2-4 times the standard FDA-approved dose 1
• Fexofenadine offers the best balance of effectiveness and safety among second-generation antihistamines 2
• Time the medication so peak drug levels coincide with worst itching 3

Critical Safety Consideration for Elderly Patients

Avoid sedating antihistamines (diphenhydramine, hydroxyzine) in this 91-year-old patient 1:

• Sedating antihistamines are associated with cognitive decline and increased risk of dementia in elderly patients (Strength of recommendation C) 1
• They also impair driving ability and increase risk of cardiovascular events 1

Second-Line Options if Initial Escalation Fails

If symptoms persist after 2 weeks of the above interventions, consider gabapentin 1:

• Gabapentin specifically benefits elderly patients with pruritus (Strength of recommendation D) 1
• This is preferred over sedating antihistamines in the geriatric population 1

Alternative systemic agents to consider 1:

• Mirtazapine: Has both antihistaminic and antidepressant properties 1
• Pregabalin: Similar mechanism to gabapentin 1
• Ondansetron or aprepitant: Particularly if nausea accompanies symptoms 1
• Paroxetine or fluvoxamine: SSRIs that may help pruritus 1

When to Refer to Secondary Care

Refer to dermatology if 1:

• Diagnostic uncertainty exists (particularly to rule out bullous pemphigoid or underlying malignancy)
• Symptoms remain uncontrolled despite the above interventions
• Patient is significantly distressed by symptoms despite primary care management

Special Considerations for Urticaria vs. Pruritus

Since this patient has welts (urticaria) in addition to itching, this suggests an urticarial process rather than pure pruritus:

• Cetirizine may be more effective than fexofenadine for chronic idiopathic urticaria 4, so consider switching from fexofenadine to cetirizine 10 mg daily
• However, cetirizine causes noticeable sedation in approximately 10% of patients 2, which is concerning in a 91-year-old
• If urticaria is the primary presentation, ensure the patient has an epinephrine autoinjector if there is any history of systemic symptoms or concern for progression to anaphylaxis 1

Common Pitfalls to Avoid

• Do not assume antihistamine failure means the diagnosis is wrong—many patients require combination therapy or higher doses 1, 3
• Do not use crotamiton cream, topical capsaicin, or calamine lotion—these are not effective for generalized pruritus of unknown origin 1
• Do not overlook asteatotic eczema—this is the most common cause in elderly patients and requires emollients plus topical steroids 1
• Do not prescribe long-term sedating antihistamines in elderly patients due to dementia risk 1