Adding oral antihistamines to existing eczema treatments is unlikely to lead to clinically important reductions in eczema and itch severity, and may not reduce sleep disturbance or flare-ups, finds a review of the latest trial evidence published by The BMJ today.
Some antihistamines may also increase side effects such as drowsiness and the risk of patients stopping treatment.
The researchers say this review addresses longstanding uncertainty surrounding the role of antihistamines in treating eczema, and the results do not support their use in routine eczema management.
Atopic dermatitis, commonly known as eczema, is a chronic condition caused by an overactive immune system that leads to dry, inflamed, and intensely itchy skin. It also often impairs quality of life, mental health, and social relationships.
Oral antihistamines are one of the most commonly used drugs for managing eczema, with an estimated one in five UK patients and nearly half of patients in the US using them. Yet despite their widespread use, evidence-based assessments of their benefits and harms in treating eczema remain inconclusive.
To address this uncertainty, researchers reviewed the results of 47 randomised controlled trials involving 6,230 children and adults (average age 20 years; 52% female) with mainly moderate to severe eczema.
The trials compared the effects of adding oral H1 antihistamines, H2 blockers, mast cell stabilizers, or their combinations to placebo (with or without background moisturisers or steroid creams) on eczema severity, itch severity, sleep disturbance, flare-ups and quality of life, as well as harms such as sedation and drowsiness.
The trials were of varying quality, but the researchers were able to assess their risk of bias and certainty of evidence using established tools.
The results show that compared with placebo, H1 antihistamines likely result in a small but clinically unimportant reduction in eczema severity and itch severity and may not reduce sleep disturbance or flare-ups.
First generation (sedating) antihistamines also probably increase cognitive impairment such as sedation and drowsiness, and may increase the risk of stopping treatment due to side effects.
The researchers acknowledge several limitations related to the nature of the included trials, but say these were addressed using standardised and systematic approaches.
As such, they conclude: "This systematic review and network meta-analysis addresses the longstanding uncertainty surrounding the role of antihistamines in treating atopic dermatitis, showing they likely do not meaningfully improve patient important outcomes while probably increasing harms."
They add: "Our findings do not support their use in routine atopic dermatitis management. We have provided a foundation for an evidence based change in practice, supporting the development of updated atopic dermatitis guidelines that prioritise efficacy, safety, and patient centred care."
