Oral H1 antihistamines as monotherapy for eczema

Eczema is a common skin disease in many countries, and although the majority of cases of eczema occur before the age of five years and often resolve during childhood or adolescence, it can also persist into adulthood. Itch is the most important aspect of eczema, often impacting significantly on the quality of life of an affected individual.

To assess the effects of oral antihistamines (H1 antagonists) as monotherapy in children and adults with eczema.

We searched the following databases up to March 2012: the Cochrane Skin Group Specialised Register, CENTRAL in The Cochrane Library (2012, Issue 3), MEDLINE (from 1946), EMBASE (from 1974), and LILACS (from 1982). We examined the reference lists of excluded studies in order to identify further references to relevant trials. We searched trials registers for ongoing and unpublished trials. We also handsearched the abstracts of the International Research Workshops on eczema, as well as the conference proceedings of the European Academy of Dermatology and Venereology (EADV) and the European Academy of Allergology and Clinical Immunology (EAACI), from 2000 to 2011.

We sought to include randomised controlled trials that assessed the effects and safety of oral H1 antihistamines as monotherapy in children and adults with eczema. We excluded studies that compared an antihistamine versus another antihistamine and had no placebo control arm. We also excluded topical antihistamines and oral H1 antihistamines as 'add-on' therapy and studies using any concomitant therapy other than emollients or moisturisers, principally because some of these forms of concomitant therapy may be considered treatment modifiers in assessments of the effects of antihistamines on eczema.

Our search retrieved 409 references to studies. Based on assessments of their titles, abstracts, or both, we excluded all except 36 of these studies. After evaluation of the full text of each report, we excluded a further 35 studies, and 1 study is awaiting classification pending a response from the trial investigators.

No randomised controlled trials met our inclusion criteria.

There is currently no high-level evidence to support or refute the efficacy or safety of oral H1 antihistamines used as monotherapy for eczema. Because most of the studies allowed the use of concomitant medications and involved multi-therapeutic approaches, meaningful assessments of the individual effects of oral H1 antihistamines on eczema were not feasible. Although well-designed randomised controlled trials excluding concomitant medications appear to be needed, consideration should be given to the potential ethical issues raised with the use of antihistamines as monotherapy for the management of eczema by withholding the use of rescue or additional therapies. A further systematic review of studies in which concomitant therapies were permitted might be of value in determining the potential benefits of oral H1 antihistamines as add-on therapy.