Background: Omalizumab, an anti-IgE monoclonal antibody, is an effective treatment for patients with chronic spontaneous urticaria (CSU) resistant to antihistamines, but about 10% are unresponsive. Our aim was to assess the effectiveness, safety, and drug survival (DS) of omalizumab by considering clinical and laboratory characteristics. Methods: We conducted a retrospective study on 296 patients with severe CSU treated with omalizumab. Disease activity, comorbidities, and serum levels of total IgE and anti-thyroid autoantibodies were evaluated over a period of up to 8 years. DS was analyzed using unadjusted Kaplan–Meier survival curves. When applicable, the risk of discontinuation was assessed using Cox regression analysis. Results: Out of 296 patients, 118 (40.4%) were early responders, 72 (25.0%) were late responders, 76 (26.0%) were partial responders, and 25 (8.6%) were non-responders. Early responders were more likely to be patients without associated inducible urticaria (p = 0.021, χ² = 9.692), without autoimmune thyroiditis (p = 0.007, χ² = 12.037), and those with higher IgE levels (p = 0.039, χ² = 8.385). Overall, DS was 53.5% at 8 years, primarily due to clinical remission. DS due to inefficacy and clinical remission were 83.9% and 62.1%, respectively, at 8 years. No patients discontinued omalizumab due to adverse events. Patients with normal IgE levels (p = 0.012, HR = 4.639, CI: 1.393–15.445) and those with autoimmune thyroiditis (p = 0.028, HR = 3.316, CI: 1.128–8.718) had a higher risk of discontinuing omalizumab due to inefficacy. Conclusions: This study confirms the long-term effectiveness and safety of omalizumab in the treatment of CSU over a period of up to 8 years. Most patients discontinued omalizumab due to clinical remission, while only 5.1% discontinued it due to ineffectiveness.

Background/Objectives: Drug hypersensitivity reactions (DHRs) are an important cause of morbidity in hospitalized patients, but their epidemiology and management in the inpatient setting are not well defined. Mislabeling of drug allergies may lead to inappropriate treatment and reduced antimicrobial stewardship. This study aimed to characterize the clinical profile, diagnostics, and management of inpatients referred for suspected drug allergy in a tertiary care hospital. Methods: We retrospectively reviewed all adult inpatients (≥18 years) at Luigi Sacco Hospital (Milan, Italy) who received allergology consultation between 1 June 2022 and 31 May 2025. Data on demographics, reaction type, culprit drugs, investigations, and management were collected. Immediate reaction severity was graded using the United States Drug Allergy Registry (USDAR) scale; delayed reactions were classified as severe cutaneous adverse reactions (SCARs) or non-SCARs. Logistic regression identified predictors of severity. Results: Among 35,438 admissions, 334 patients (0.9%) were evaluated; median age was 65 years, 51.2% were female, 67.4% had atopic comorbidities, and 55.1% reported prior drug allergy. Immediate reactions occurred in 49.1%, delayed in 43.7%. Cutaneous involvement was present in 86.8%, anaphylaxis in 6.6%, and SCARs in 3.9%. Antibiotics—particularly β-lactams—were most often implicated. In multivariate analysis, antibiotic exposure and older age were linked to more severe immediate reactions, while the absence of atopy predicted SCARs. Desensitization was successfully performed in 16.2% of patients. Conclusions: DHRs in inpatients are frequent and often involve high-risk drugs. Structured inpatient allergology services and an “allergy stewardship” approach may reduce DHR-related risks, support optimal therapy, and improve antimicrobial use strategies in tertiary care settings.

Non-allergic rhinitis with eosinophilia syndrome (NARES) is a chronic inflammatory rhinopathy characterized by nasal obstruction, rhinorrhea, sneezing and/or an itchy nose. Although eosinophilic nasal cytology is common in NARES patients, identifying the condition is challenging due to a lack of consensus on the diagnostic processes and the role of nasal cytology in clinical practice. Patients may undergo several allergy tests with negative or inconclusive results and are eventually diagnosed with idiopathic/aspecific rhinitis. Treatment options may include intranasal corticosteroids, intranasal antihistamines or a combination of both types of medication. This case report describes a patient with NARES who was unresponsive to conventional therapies and experienced significant improvement after treatment with Mepolizumab, a drug approved for severe asthma with hypereosinophilia, hypereosinophilic syndrome (HES), chronic rhinosinusitis with nasal polyposis (CRSwNP) and eosinophilic granulomatosis with polyangiitis (EGPA). Mepolizumab was administered once a month at a dose of 100 mg subcutaneously. The patient experienced a complete remission of symptoms a year after starting the off-label treatment. Blood counts remained stable and no adverse effects were observed. Mepolizumab appears to be a potential therapeutic alternative in patients with NARES who are unresponsive to conventional therapies.

Scombroid syndrome is a frequent cause of fish poisoning and typically presents with mild, self-limiting symptoms. Severe anaphylaxis-like reactions are uncommon, and a biphasic clinical course has not previously been reported. We describe the case of a 19-year-old woman who developed flushing, headache, generalized urticaria, facial edema, dyspnea, and hypotension approximately 30 minutes after ingesting raw amberjack tartare. Emergency treatment with adrenaline, antihistamines, corticosteroids, and intravenous fluids led to initial clinical improvement; however, three hours later, she experienced a recurrence of cutaneous, respiratory, and gastrointestinal symptoms, consistent with a biphasic reaction. The patient subsequently developed chest pain associated with transient electrocardiographic changes and mild troponin elevation, prompting further evaluation for suspected Kounis syndrome. Allergy assessment, including specific IgE testing and skin-prick testing with fresh fish, was negative, supporting a toxic rather than IgE-mediated mechanism. This case expands the clinical spectrum of scombroid syndrome by documenting a biphasic anaphylaxis-like presentation and underscores the importance of considering histamine fish poisoning in the differential diagnosis of severe food-related reactions. Careful evaluation is essential to prevent misdiagnosis and unnecessary long-term dietary restrictions.