Cold urticaria (ColdU) is a common form of chronic inducible urticaria characterized by the development of wheals, angioedema or both in response to cold exposure. Recent research and guideline updates have advanced our understanding and management of ColdU. Today, its pathophysiology is thought to involve the cold‐induced formation of autoallergens and IgE to these autoallergens, which provoke a release of proinflammatory mediators from skin mast cells. The classification of ColdU includes typical and atypical subtypes. We know that cold‐induced wheals usually develop on rewarming and resolve within an hour and that anaphylaxis can occur. The diagnosis relies on the patient's history and cold stimulation testing. Additional diagnostic work‐up, including a search for underlying infections, should only be done if indicated by the patient's history. The management of ColdU includes cold avoidance, the regular use of nonsedating antihistamines and the off‐label use of omalizumab. However, many questions regarding ColdU remain unanswered. Here, we review what is known about ColdU, and we present important unanswered questions on the epidemiology, underlying pathomechanisms, clinical heterogeneity and treatment outcomes. Our aim is to guide future efforts that will close these knowledge gaps and advance the management of ColdU.

This update and revision of the international guideline for urticaria was developed in accordance with the methods recommended by Cochrane and the Grading of Recommendations Assessment, Development and Evaluation (GRADE) working group. It is an initiative of the Global Allergy and Asthma Excellence Network (GA ² LEN) and its Urticaria and Angioedema Centers of Reference and Excellence (UCAREs and ACAREs), with the participation of 210 delegates from 107 national and international societies, from 59 countries. The consensus conference was held on December 6th, 2024. This guideline was acknowledged and accepted by the European Union of Medical Specialists (UEMS). Urticaria is a frequent, mast cell‐driven disease, defined by a rapid appearance of wheals, angioedema, or both. The lifetime prevalence of acute urticaria is estimated to be approximately 20%. Chronic urticaria, categorized as either chronic spontaneous urticaria or chronic inducible urticaria, is disabling, impairs quality of life, and affects performance at work and school, however, novel therapies are available. This updated version of the international guideline for urticaria covers the definition and classification of urticaria and outlines expert‐guided and evidence‐based diagnostic and therapeutic approaches for the different subtypes of urticaria.

Introduction: The COVID‐19 pandemic dramatically disrupts health care around the globe. The impact of the pandemic on chronic urticaria (CU) and its management are largely unknown.Aim: To understand how CU patients are affected by the COVID‐19 pandemic; how specialists alter CU patient management; and the course of CU in patients with COVID‐19.Materials and Methods: Our cross‐sectional, international, questionnaire‐based, multicenter UCARE COVID‐CU study assessed the impact of the pandemic on patient consultations, remote treatment, changes in medications, and clinical consequences.Results: The COVID‐19 pandemic severely impairs CU patient care, with less than 50% of the weekly numbers of patients treated as compared to before the pandemic. Reduced patient referrals and clinic hours were the major reasons. Almost half of responding UCARE physicians were involved in COVID‐19 patient care, which negatively impacted on the care of urticaria patients. The rate of face‐to‐face consultations decreased by 62%, from 90% to less than half, whereas the rate of remote consultations increased by more than 600%, from one in 10 to more than two thirds. Cyclosporine and systemic corticosteroids, but not antihistamines or omalizumab, are used less during the pandemic. CU does not affect the course of COVID‐19, but COVID‐19 results in CU exacerbation in one of three patients, with higher rates in patients with severe COVID‐19.Conclusions: The COVID‐19 pandemic brings major changes and challenges for CU patients and their physicians. The long‐term consequences of these changes, especially the increased use of remote consultations, require careful evaluation.

Background: Cold urticaria (ColdU), that is, the occurrence of wheals or angioedema in response to cold exposure, is classified into typical and atypical forms. The diagnosis of typical ColdU relies on whealing in response to local cold stimulation testing (CST). It can also manifest with cold‐induced anaphylaxis (ColdA). We aimed to determine risk factors for ColdA in typical ColdU.Methods: An international, cross‐sectional study COLD‐CE was carried out at 32 urticaria centers of reference and excellence (UCAREs). Detailed history was taken and CST with an ice cube and/or TempTest^® performed. ColdA was defined as an acute cold‐induced involvement of the skin and/or visible mucosal tissue and at least one of: cardiovascular manifestations, difficulty breathing, or gastrointestinal symptoms.Results: Of 551 ColdU patients, 75% (n = 412) had a positive CST and ColdA occurred in 37% (n = 151) of the latter. Cold‐induced generalized wheals, angioedema, acral swelling, oropharyngeal/laryngeal symptoms, and itch of earlobes were identified as signs/symptoms of severe disease. ColdA was most commonly provoked by complete cold water immersion and ColdA caused by cold air was more common in countries with a warmer climate. Ten percent (n = 40) of typical ColdU patients had a concomitant chronic spontaneous urticaria (CSU). They had a lower frequency of ColdA than those without CSU (4% vs. 39%, p = .003). We identified the following risk factors for cardiovascular manifestations: previous systemic reaction to a Hymenoptera sting, angioedema, oropharyngeal/laryngeal symptoms, and itchy earlobes.Conclusion: ColdA is common in typical ColdU. High‐risk patients require education about their condition and how to use an adrenaline autoinjector.

Background: Chronic urticaria (CU) is a common disease, characterized by the recurrent appearance of wheals, angioedema or both for more than 6 weeks. Its underlying biology is not well understood, and many patients do not obtain sufficient relief from recommended treatments. Patient registries are rapidly growing as a form of research, because they can provide powerful, data‐driven insights about the epidemiology of diseases, real‐world effectiveness of treatments, rare patient types, safety monitoring, healthcare costs and opportunities for quality improvement of healthcare delivery.Objectives: The Chronic Urticaria Registry (CURE) has been designed to improve the scientific understanding, clinical treatment and healthcare planning of CU patients. This report describes the rationale, methods and initial implementation of this registry.Methods: Chronic Urticaria Registry is an ongoing, prospective, international, multicentre, observational, voluntary registry of patients with CU. Participation in CURE is open to any physician treating CU patients, regardless of location, medical specialty or type of practice setting. CURE aims to collect data on all CU patients, with no intentional selection or exclusion criteria. It collects baseline and follow‐up data on the patient's demographics, history, symptoms, trigger and risk factors, therapies and healthcare utilization.Results: Chronic Urticaria Registry is a landmark achievement of the global urticaria medical community. As of 26 February 2020, 39 centres around the world have joined the registry and 35 have entered baseline data on a total of 2946 patients. Publications of this data will be forthcoming soon.Conclusions: Chronic Urticaria Registry is eagerly seeking the participation of more physicians and the support of more governmental, charitable and commercial sponsors from around the world. Here, in this paper, we invite other physicians to join this unique project to improve the lives of patients with CU.