Background
Allergic rhinitis is a very common chronic illness affecting 10% to 40% of children worldwide and its prevalence among children has significantly increased over the last two decades. Prevalence and severity are related to age, with children of school age most commonly affected.

Objectives
To assess the effectiveness and adverse event profile of antihistamines (oral or topical) used as an adjunct to topical nasal steroids for intermittent and persistent allergic rhinitis in children.

Search strategy
We searched the Cochrane Ear, Nose and Throat Disorders Group Trials Register; the Cochrane Central Register of Controlled Trials (CENTRAL); MEDLINE; EMBASE; CINAHL; Web of Science; BIOSIS Previews; Cambridge Scientific Abstracts; mRCT and additional sources for published and unpublished trials. The date of the most recent search was 21 September 2009.

Selection criteria

Randomised controlled trials (RCTs) in children under the age of 18 with a history of allergic rhinitis, with or without allergic conjunctivitis or asthma, comparing topical nasal steroids with antihistamines to topical nasal steroids only.

Data collection and analysis
Two review authors independently screened studies, extracted data and assessed risk of bias.

Main results
One study including 24 participants met the inclusion criteria for this review. This study compared the administration of topical nasal steroids with oral antihistamines to topical nasal steroids only in children, but it did not provide sufficient data to address the clinical question of this review.

Authors' conclusions
In view of the lack of evidence for the benefit or lack of benefit of antihistamine add-on therapy with topical nasal steroids for children with intermittent or persistent allergic rhinitis, it is important that clinicians are mindful of the adverse effects of antihistamines and the additional costs that may be incurred.