Objective:

To evaluate the effectiveness of oral antihistamines in treating atopic dermatitis severity and itch in pediatric and adult patients.

Approach:

• Study Design: Systematic review and network meta-analysis of 47 randomized trials involving 6,230 patients.
• Data Sources: Data was collected from Medline, Embase, CENTRAL, and regulatory databases from inception through May 5, 2025.
• Analysis Method: Bayesian random-effects network meta-analyses were conducted, assessing treatment effects and certainty using the Grading of Recommendations Assessment, Development, and Evaluation approach.

Key Findings:

• Second-generation H1 antihistamines reduced Scoring Atopic Dermatitis scores by approximately 2 points compared to placebo, which is below the minimal important difference.
• First-generation H1 antihistamines did not produce a clinically important difference in disease severity or itch.
• Increasing antihistamine doses may not improve itch, with very uncertain evidence.
• First-generation H1 antihistamines likely increased cognitive impairment, with an estimated 66 additional events of cognitive impairment per 1,000 patients.
• No significant difference in serious adverse events between antihistamines and placebo.

Interpretation:

The review found moderate and high certainty evidence of harms and no clinically important benefit of oral antihistamines added to placebo with or without background topical treatments.

Limitations:

• Trial populations differed in baseline disease severity.
• Subgroup analyses may have been limited by small sample sizes.
• Some crossover trials reported outcomes across the entire trial rather than by crossover period.

Conclusion:

The findings indicate the need for updated clinical practice guidelines regarding the use of oral antihistamines in atopic dermatitis treatment.

Sources:

• The BMJ