Antihistamines for atopic dermatitis (eczema): systematic review and network meta-analysis of randomised trials.

OBJECTIVE

To systematically synthesise the benefits and harms of add-on oral antihistamines for managing atopic dermatitis (eczema).

DESIGN

Systematic review and network meta-analysis of randomised trials.

DATA SOURCES: Medline, Embase, CENTRAL, the United States Food and Drug Administration, and the European Medicines Agency databases from database inception to 5 May 2025.

STUDY SELECTION: Randomised trials assessing add-on oral H1 antihistamines, H2 blockers, mast cell stabilisers (nedocromil sodium and sodium cromoglycate), or their combinations. Paired reviewers independently screened records, extracted data, and assessed risk of bias using a modified Cochrane Risk of Bias tool version 2.

METHODS

Random effects bayesian meta-analyses synthesised atopic dermatitis severity (oSCORAD-objective scoring atopic dermatitis, 0-83; minimal important difference 8.2; lower better), itch severity (numerical rating scale, 0-10; minimal important difference 3; lower better), sleep disturbance, atopic dermatitis related quality of life, and harms. The network meta-analysis GRADE (Grading of Recommendations Assessment, Development and Evaluation) and Core GRADE approaches informed certainty of evidence ratings.

RESULTS

47 trials enrolled 6230 children and adults with primarily moderate to severe atopic dermatitis. With moderate certainty, compared with placebo, adding a first generation or second generation H1 antihistamine likely resulted in a small reduction in atopic dermatitis severity (mean difference -1.87, 95% credible interval -3.47 to -0.27) and itch severity (-0.89, -1.41 to -0.37). Although statistically detectable, these effects are well below established minimal important differences (smallest change in an outcome that a patient would identify as important). With low certainty, all studied interventions may not improve sleep disturbance or reduce atopic dermatitis exacerbations. First generation agents probably increase cognitive impairment and may increase treatment discontinuation because of adverse events (risk difference 66 more per 1000, 95% credible interval 0 to 231 more; moderate certainty). Second generation agents differ in their risk of cognitive impairment (range of mean effects 0 more per 1000 for loratadine, 16 more per 1000 for levocetirizine, and 17 more per 1000 for cetirizine).

CONCLUSIONS

Among patients with atopic dermatitis, adding H1 antihistamines probably results in a clinically unimportant reduction in atopic dermatitis severity and itch severity, and may not reduce sleep disturbance or atopic dermatitis exacerbations. First generation agents increase cognitive impairment and may increase treatment discontinuation because of adverse events. Cognitive impairment risk differs among second generation agents. These findings provide evidence against routine antihistamine use in atopic dermatitis management and will inform updated clinical guidelines.

SYSTEMATIC REVIEW REGISTRATION: PROSPERO CRD42022345643.