Urticaria: A Narrative Overview of Differential Diagnosis

Efficacy and safety of combinations of H1 antihistamines in the treatment of urticaria: A scoping review

The efficacy and safety of combining H1 antihistamines (AHs) for treating urticaria are currently unclear. This scoping review aims to provide a comprehensive overview of the evidence regarding the efficacy and safety of H1 AH combinations in the management of urticaria up to May 2023. The search encompassed databases such as PubMed, Web of Science, the Cochrane Central Register of Controlled Trials, and the China Biological Medicine Database. The inclusion criteria comprised randomised controlled trials (RCTs), non-randomised trials (NRTs), case reports, and case series focusing on urticaria treatment. Initially screening 12,887 studies, this review ultimately selected 109 studies involving 11,435 patients. These studies documented 43 different combination treatments across 11 types of urticaria. In comparison to monotherapy, combination therapy exhibited superior efficacy in 94 studies that reported treatment efficacy. Regarding adverse drug reactions (ADRs), 67 studies disclosed ADR incidences, with combination therapy showing lower ADR rates in 32 studies. Additionally, 7 studies reported similar ADR rates between combination therapy and monotherapy with AHs. Common ADRs included symptoms such as drowsiness, nausea, fatigue, dry mouth, dizziness, and headache, while less frequent side effects encompassed hypotension, otitis media, polyuria, rhinorrhoea, abnormal liver function, and rash. ADR rates ranged from 0% to 21% in the treatment group, and from 0.5% to 75% in the control group. Importantly, patients generally tolerated these ADRs well, with symptoms resolving upon discontinuation of treatment. The study's findings suggest that combining AHs leads to enhanced efficacy and reduced safety risks compared to monotherapy in the context of urticaria treatment. These results advocate for considering combination therapy as a viable option in clinical practice, especially for chronic urticaria cases. Nonetheless, caution is advised, and close monitoring for potential ADRs is crucial during treatment.

A Practical Approach to Diagnosing and Managing Chronic Spontaneous Urticaria

Chronic spontaneous urticaria (CSU) is an unpredictable inflammatory skin condition characterized by the spontaneous onset of itchy wheals, angioedema, or both, which occurs for longer than 6 weeks overall. Despite the relatively straightforward diagnostic algorithm for CSU, relying primarily on a detailed medical history and only limited laboratory tests, patients often wait years to be diagnosed, with many cycling through different healthcare practitioners before a diagnosis is made. Even then, current treatment options for CSU are limited, with approximately half of patients resistant to standard-of-care second-generation antihistamines at standard or higher doses. As such, there is an unmet need for improved, streamlined management for patients with CSU. Here, we review the evidence-based diagnostic algorithm for CSU, consider the required steps of the diagnostic workup, and provide practical, real-world advice on the management of CSU to improve the timely diagnosis and care of patients with this debilitating disease.

Immunological Mechanisms in Cutaneous Adverse Drug Reactions

Adverse drug reactions (ADRs) are an inherent aspect of drug use. While approximately 80% of ADRs are predictable, immune system-mediated ADRs, often unpredictable, are a noteworthy subset. Skin-related ADRs, in particular, are frequently unpredictable. However, the wide spectrum of skin manifestations poses a formidable diagnostic challenge. Comprehending the pathomechanisms underlying ADRs is essential for accurate diagnosis and effective management. The skin, being an active immune organ, plays a pivotal role in ADRs, although the precise cutaneous immunological mechanisms remain elusive. Fortunately, clinical manifestations of skin-related ADRs, irrespective of their severity, are frequently rooted in immunological processes. A comprehensive grasp of ADR morphology can aid in diagnosis. With the continuous development of new pharmaceuticals, it is noteworthy that certain drugs including immune checkpoint inhibitors have gained notoriety for their association with ADRs. This paper offers an overview of immunological mechanisms involved in cutaneous ADRs with a focus on clinical features and frequently implicated drugs.