I started levocetirizine (Telekast) and ebastine 10 mg for urticaria; itching resolved but I now have abdominal bloating and constipation—how should I manage these side effects?

Managing Antihistamine-Related Gastrointestinal Side Effects in Urticaria

Switch from levocetirizine (Telekast) to ebastine 10 mg once daily, as ebastine demonstrates significantly better gastrointestinal tolerability with less constipation and dry mouth while maintaining equivalent efficacy for urticaria control. 1

Understanding Your Current Side Effects

Your bloating and constipation are anticholinergic effects from the antihistamines you're taking. Both levocetirizine and ebastine 10 mg can cause these symptoms, but the evidence shows important differences:

• Levocetirizine causes significantly more dry mouth and sedation compared to ebastine at equivalent doses, with these anticholinergic effects directly contributing to constipation and gastrointestinal discomfort 1
• Ebastine 10 mg demonstrates superior tolerability with fewer gastrointestinal side effects compared to levocetirizine 5 mg, despite similar efficacy for urticaria control 1, 2

Recommended Treatment Algorithm

Step 1: Switch Your Antihistamine

• Discontinue levocetirizine and start ebastine 10 mg once daily, as this provides equivalent urticaria control with significantly better gastrointestinal tolerability 1, 2
• Ebastine 10 mg is as effective as levocetirizine 5 mg for urticaria but with a highly significant reduction in side effects (p<0.001) 1

Step 2: If Urticaria Control Becomes Inadequate

• Increase ebastine to 20 mg once daily rather than adding back levocetirizine, as ebastine 20 mg shows superior efficacy to ebastine 10 mg while maintaining the same excellent tolerability profile 1, 2
• Ebastine 20 mg achieves 80% complete symptom resolution (UAS7=0) compared to 70% with levocetirizine 5 mg, with significantly fewer side effects 1

Step 3: Manage Residual Constipation

• Increase dietary fiber and fluid intake immediately to counteract anticholinergic effects on bowel motility 3
• Consider adding a stool softener (docusate) or osmotic laxative (polyethylene glycol) if constipation persists beyond 1 week after switching antihistamines 3

Why This Approach Works

• Ebastine has minimal anticholinergic effects compared to levocetirizine, directly addressing the mechanism causing your constipation and bloating 1, 2
• Ebastine provides 24-hour efficacy with once-daily dosing and requires no dose adjustment for renal or mild-to-moderate hepatic impairment 2, 4
• Ebastine has no clinically relevant effects on cognitive function or psychomotor performance at both 10 mg and 20 mg doses 2, 4

Critical Pitfalls to Avoid

• Do not add a first-generation antihistamine at bedtime to help with sleep, as this will worsen anticholinergic side effects and cause prolonged daytime drowsiness 5
• Do not combine multiple antihistamines simultaneously (e.g., continuing levocetirizine while adding ebastine), as this increases anticholinergic burden without meaningful additional benefit 5
• Avoid NSAIDs and aspirin, as they can worsen urticaria through cyclooxygenase inhibition 6
• Minimize alcohol, stress, and overheating, as these aggravate urticaria symptoms 6

If Symptoms Persist Despite Switching

• If urticaria remains uncontrolled after 2-4 weeks on ebastine 20 mg, consider adding an H2 antihistamine (cimetidine) rather than increasing antihistamine doses further, as H2 blockers may provide better urticaria control when combined with H1 antihistamines 6, 5
• If inadequate control persists despite optimized antihistamine therapy, omalizumab 300 mg every 4 weeks is the next-line therapy 6, 5