What antihistamines are safe for patients with impaired renal function (dialysis)?

Antihistamine Use in Dialysis Patients

Fexofenadine 180 mg once daily is the preferred antihistamine for dialysis patients because it requires no dose adjustment and has the best safety profile in end-stage renal disease. 1, 2

First-Line Antihistamine Selection

Fexofenadine is the only second-generation antihistamine that can be given at full dose without adjustment in dialysis patients. 1, 2

• The FDA-approved dosing for fexofenadine in patients with decreased renal function is 60 mg once daily as a starting dose, though 180 mg daily is preferred for urticaria and can be used safely 2
• Fexofenadine can be updosed to 4-fold (up to 720 mg daily) if needed for refractory urticaria, with minimal increase in side effects 1

Antihistamines to Avoid or Use with Caution

Cetirizine should be avoided in dialysis patients - it is specifically ineffective for uremic pruritus and contraindicated in severe renal impairment (CrCl <10 mL/min). 3, 1, 4

First-generation sedating antihistamines (diphenhydramine, hydroxyzine) must be avoided except in palliative care due to increased risk of falls, sedation, and potential long-term dementia risk. 3, 1, 4

Loratadine should be used with extreme caution in severe renal impairment, as its metabolite accumulates significantly (AUC increased 2-fold in renal failure patients). 1, 4, 5

Levocetirizine should be avoided in severe renal impairment (CrCl <10 mL/min). 1, 4

Special Considerations for Uremic Pruritus

Antihistamines have limited efficacy for uremic pruritus specifically - if the patient's itching is related to uremia rather than true urticaria or allergic conditions, consider alternative treatments first. 3, 4

Gabapentin 100-300 mg after each dialysis session (three times weekly) is more effective than antihistamines for uremic pruritus, with response rates superior to any antihistamine. 3, 1, 4

• Ketotifen 1 mg daily may be considered as an alternative antihistamine with some evidence for uremic pruritus, though data are limited 4
• Optimize dialysis adequacy (target Kt/V ~1.6) and normalize calcium-phosphate balance before escalating pharmacotherapy 1, 4
• Topical capsaicin 0.025% cream four times daily provides marked relief for many patients with uremic pruritus 1

Dosing Timing

Administer antihistamines after hemodialysis sessions to avoid premature drug removal and facilitate adherence. 3, 6

Common Pitfalls to Avoid

• Do not assume all second-generation antihistamines are equivalent in dialysis - only fexofenadine requires no adjustment 1, 2
• Do not prescribe cetirizine for dialysis patients despite its popularity in the general population - it accumulates and is ineffective for uremic pruritus 3, 1, 7
• Do not use standard antihistamine dosing for loratadine without considering metabolite accumulation 5
• Do not rely solely on antihistamines for uremic pruritus when gabapentin has superior efficacy 3, 1, 4