Chronic urticaria: off-label doses of cetirizine

How well does cetirizine work?

Four small studies have looked at how well cetirizine 20 mg (double the standard dose) works for treating chronic urticaria when symptoms haven't improved with standard doses of antihistamines. Most people in the studies were aged 16−65 years. No studies included children and young people under 16 and there were very few older adults (over 65 years). No studies looked at cetirizine 40 mg, a dose that is sometimes used for treating chronic urticaria.

Overall, the studies suggest that cetirizine 20 mg improves rash and itching in adults compared with placebo (a dummy tablet) or a standard 10 mg dose of cetirizine. However, not everyone had improvements in their symptoms. Also, because of the small size and the design of the studies, they do not provide good evidence about the benefits and harms of cetirizine.

What are the possible harms or side effects?

Standard doses of cetirizine (10 mg) can cause tiredness, dizziness, headache, abdominal pain, dry mouth, nausea, drowsiness and sore throat. However, few adverse effects were reported in the small studies and cetirizine seemed to be well tolerated.