Treatment of Urticaria in Dialysis Patients
For true urticaria in dialysis patients, use fexofenadine 180 mg daily as the first-line antihistamine without dose adjustment, and if symptoms persist after 2-4 weeks, increase to up to 4 times the standard dose before considering omalizumab 300 mg every 4 weeks as second-line therapy. 1, 2
Critical Distinction: Urticaria vs. Uremic Pruritus
Before treating, you must differentiate between true urticaria (wheals with or without angioedema) and uremic pruritus (itch without primary skin lesions), as they require completely different treatment approaches 3:
- True urticaria presents with raised, erythematous wheals that blanch with pressure and may have angioedema 2
- Uremic pruritus presents with itch but no primary wheals, often generalized or localized to the back, face, or arteriovenous fistula arm 4
Treatment Algorithm for True Urticaria in Dialysis Patients
First-Line: Second-Generation Antihistamines
Fexofenadine 180 mg daily is the preferred agent because it requires no dose adjustment in renal impairment. 1
Critical medication selection for dialysis patients:
- Use fexofenadine 180 mg daily - no dose adjustment needed 1
- Avoid cetirizine and levocetirizine in severe renal impairment (CrCl <10 mL/min) due to accumulation risk 1, 5
- Use loratadine with extreme caution in severe renal impairment 1
- Never use long-term sedating antihistamines (diphenhydramine, hydroxyzine) except in palliative care, as they predispose to dementia 1, 4
Updosing Strategy
If symptoms remain inadequately controlled after 2-4 weeks (or earlier if intolerable), increase the antihistamine dose up to 4-fold 2, 6:
- Approximately 75% of patients with difficult-to-treat urticaria respond to higher-than-conventional antihistamine doses 6, 7
- For fexofenadine, this means up to 720 mg daily (180 mg four times daily) 2
- Updosing improves symptoms without significantly increasing somnolence 6
- Only 17-20% of patients experience side effects, primarily mild somnolence 7
Some patients may benefit from doses even higher than 4-fold (up to 8-12 times standard dose), which decreases the need for third-line therapies by 49% with minimal additional side effects (10% vs 20% at standard updosing). 7
Second-Line: Omalizumab
If inadequate control persists despite maximally updosed antihistamines, add omalizumab 300 mg subcutaneously every 4 weeks 2:
- Effective in approximately 70% of antihistamine-refractory patients 8
- Continue antihistamines as background therapy 2
- Allow up to 6 months for full response 2
- If insufficient response, consider updosing omalizumab by shortening intervals and/or increasing dosage, with maximum recommended dose of 600 mg every 14 days 2
Third-Line: Cyclosporine
For patients unresponsive to maximally dosed antihistamines and omalizumab, add cyclosporine up to 5 mg/kg body weight daily 2:
- Effective in 65-70% of refractory patients 8
- Critical pitfall in dialysis patients: Cyclosporine carries significant risks including hypertension and renal failure 2
- Monitor blood pressure and renal function (BUN and creatinine) every 6 weeks 2
- Given the existing renal impairment in dialysis patients, cyclosporine should be used with extreme caution and only when benefits clearly outweigh risks 2
Common Pitfalls to Avoid
Do not confuse urticaria treatment with uremic pruritus treatment - cetirizine is ineffective specifically for uremic pruritus despite efficacy in urticaria 1, 4
Avoid chronic corticosteroids - brief courses of 3-10 days can be used for severe exacerbations, but chronic use causes cumulative toxicity 8
Do not use H2-receptor blockers or leukotriene antagonists - they add little benefit and lack supporting evidence 8
Step-Down Approach
Once complete disease control is achieved (Urticaria Control Test score >16), consider stepping down treatment gradually 2: