Allegra (Fexofenadine) for Chronic Pruritus
Fexofenadine 180 mg daily is a reasonable option for chronic pruritus of unknown origin, but its effectiveness is limited and should be considered as part of a broader treatment strategy rather than a first-line monotherapy. 1
Evidence-Based Recommendations
For Generalized Pruritus of Unknown Origin (GPUO)
The British Association of Dermatologists (2018) recommends considering nonsedative antihistamines such as fexofenadine 180 mg or loratadine 10 mg as systemic treatment options for GPUO, though the strength of recommendation is weak (Level D). 1
- Start with emollients and self-care advice as the foundation of treatment before adding systemic agents 1
- Fexofenadine can be used alone or in combination with H2 antagonists (e.g., fexofenadine plus cimetidine) for potentially enhanced effect 1
- The evidence supporting antihistamines for non-histamine-mediated pruritus is limited, as chronic pruritus often involves non-histaminergic pathways 1
FDA-Approved Indications
Fexofenadine is FDA-approved for chronic idiopathic urticaria, where it "significantly reduces pruritus and the number of wheals," but it is NOT approved for generalized chronic pruritus without urticaria. 2
- The drug's proven efficacy is specifically for urticaria-associated pruritus, not chronic pruritus in general 2
- This distinction is clinically important when setting patient expectations 2
Dosing Considerations
For chronic idiopathic urticaria, doses of 60 mg twice daily or greater (up to 240 mg twice daily) have demonstrated efficacy, with the standard dose being 180 mg daily. 3
- High-dose fexofenadine (360 mg daily) combined with other antihistamines showed a 57.5% reduction in pruritus in a retrospective case series, though monotherapy with high-dose desloratadine (89% reduction) was more effective 4
- Standard dosing (180 mg daily) should be tried first before escalating 1
Context-Specific Efficacy
For atopic dermatitis-associated pruritus, fexofenadine 60 mg twice daily showed statistically significant but modest improvement when added to topical corticosteroids (mean score reduction -0.75 vs -0.5 for placebo, p=0.0005). 5
- The clinical significance of this improvement is debatable given the small absolute difference 5
- For psoriasis-associated pruritus, fexofenadine 180 mg is mentioned as an option for severe cases, but other agents like gabapentin, pregabalin, or mirtazapine may be more effective for refractory cases 6
Important Caveats
Avoid sedating antihistamines for chronic pruritus except in short-term or palliative settings, as long-term use may predispose to dementia. 1, 6
- Fexofenadine is nonsedating, making it safer for long-term use than first-generation antihistamines 1
- Cetirizine (mildly sedating) is also an option but less preferable than fexofenadine for daytime use 1
For specific causes of chronic pruritus (uraemic, hepatic, neuropathic), antihistamines are generally ineffective and other targeted therapies should be used. 1
- Cetirizine is specifically noted as NOT effective in uraemic pruritus 1
- Always investigate and treat underlying causes before attributing pruritus to "unknown origin" 1
Alternative Approaches When Fexofenadine Fails
If fexofenadine is ineffective, consider paroxetine, fluvoxamine, mirtazapine, naltrexone, gabapentin, pregabalin, ondansetron, or aprepitant as second-line systemic agents. 1
- Phototherapy (NB-UVB) is highly effective for many types of chronic pruritus and should be considered before multiple systemic agents 1
- Topical options include doxepin (limited to 8 days, 10% body surface area), clobetasone butyrate, or menthol 1
Safety Profile
Fexofenadine is well-tolerated with adverse events similar to placebo; the most common side effect is headache (9.04% in one study), with no reports of drowsiness or cardiac arrhythmia. 3, 7