Urticaria (hives) is a common disorder that often presents with angioedema (swelling that occurs beneath the skin). It is generally classified as acute or chronic. Second-generation, non-sedating, non-impairing histamine type 1 (H1)-receptor antihistamines represent the mainstay of therapy for both acute and chronic urticaria. Angioedema can occur in the absence of urticaria and can be broadly divided into histamine-mediated and non-histaminemediated angioedema. Histamine-mediated angioedema can be allergic, pseudoallergic or idiopathic. Non-histamine mediated angioedema is largely driven by bradykinin and can be hereditary, acquired or drug-induced, such as with angiotensin-converting enzyme inhibitors. Although bradykinin-mediated angioedema is often self-limited, laryngeal involvement can lead to fatal asphyxiation. The mainstay of management for angioedema is to avoid specific triggers, if possible. For hereditary angioedema, there are specifically licensed treatments that can be used for the management of acute attacks, or for prophylaxis in order to prevent attacks. In this article, the authors will review the causes, diagnosis and management of urticaria (with or without angioedema) and isolated angioedema. The diagnostic and therapeutic approaches to these two conditions are considerably different, and this review is designed to highlight these differences to the reader.

BackgroundCow's milk protein allergy (CMPA) is the leading cause of food allergy in infants and young children. An extensively hydrolyzed formula (eHF) is the first choice of dietary management, however, not all of them have similar peptide profiles and degree of hydrolysis. The aim of this retrospective study was to investigate the use of two commercially available infant formulas in the clinical management of CMPA in Mexico in terms of symptoms' resolution and growth trajectories.MethodsMedical records of 79 subjects from four sites in Mexico were included to retrospectively evaluate the trajectory of atopic dermatitis, other symptoms of cow's milk protein allergy and growth outcomes. The study formulas were based on hydrolyzed whey protein (eHF-W) and hydrolyzed casein protein (eHF-C).ResultsMedical records of 79 patients were enrolled, 3 were excluded from analysis based on previous formula consumption. Seventy-six children with confirmed CMPA based on skin prick test and/or serum specific IgE levels were included in the analysis. 82% of patients (n = 65) consumed the eHF-C, reflecting the doctors' preference for formulas with a higher grade of hydrolysis and the high incidence of positive reactions to beta-lactoglobulin amongst subjects. During their first visit to the doctors, 55% of the subjects consuming the casein-based formula and 45% of subjects consuming the whey-based formula presented with mild or moderate dermatological symptoms. Other frequently reported symptoms included respiratory issues, enteropathies and colitis which improved during the consumption of both formulas. All CMPA-related symptoms showed improvement during formula consumption. During the period of retrospective observation, growth significantly improved for both groups.ConclusionConsumption of eHF-C and eHF-W effectively improved symptoms' resolution and growth outcomes among children with CMPA in Mexico. More preference was reported towards eHF-C due to its hydrolysate profile and lack of b-lactoglobulin.Trial registrationThe study was registered at ClinicalTrials.gov: NCT04596059.