[Approved therapies and their effects on the main symptoms of urticaria : When symptom control of itchy wheals is not adequate-does updosing help?] / Zugelassene Therapien und ihre Wirkung auf die Leitsymptome der Urtikaria : Hilfreiche Therapieoptionen, wenn juckende Quaddeln nicht weichen ­ Viel hilft viel?

International guidelines for the treatment of chronic spontaneous urticaria support the updosing of second-generation antihistamines to four times of the approved dose when adequate symptom control cannot be achieved with the standard dosage. However, this recommendation is primarily based on expert opinions, and there is a lack of large, well-designed, double-blind clinical trials. Most the existing trials provide insufficient data, and due to the heterogeneity of the conducted trials on antihistamine effects (definition of control, design, quality, lack of an active comparator, no placebo arm, small sample size, outcomes) and their short duration, comparative analysis is challenging. However, it can be concluded that the use of modern second-generation antihistamines is both effective and safe based on the available data and our own long-term experiences in the specialized outpatient clinic of a university dermatology department, even though increased dosages (up to fourfold as per the current international guidelines) may be necessary for symptom control. Another therapeutic option for refractory symptoms in chronic spontaneous urticaria is subcutaneous administration of omalizumab at a dosage of 300 mg at 4­week intervals as a very safe and effective treatment.

A systematic review and meta-analysis of efficacy and safety of compound glycyrrhizin combined with second-generation non-sedated antihistamine for the treatment of chronic urticaria.

BACKGROUND: Chronic urticaria (CU) is a prevalent dermatologic disease that negatively affects life, current therapies remain suboptimal. Hence, there is an urgent need to identify effective and safe treatment. OBJECTIVE: Assess the efficacy and safety of compound glycyrrhizin (CG) combined with second-generation nonsedated antihistamine for the treatment of CU. METHODS: Nine databases were queried to screen RCTs related. Two reviewers independently assessed the risk of bias using Cochrane Collaboration. Primary objective was the total efficiency rate, while secondary was rate of recurrence, adverse events, and cure. Statistical analyses using Review Manager 5.4 and Stata17. RESULTS: Twenty-four RCTs were identified. Significant differences were noted in rate of total efficiency (n = 2649, RR = 1.36, 95%CI:1.30-1.43, p < 0.00001), cure (n = 2649, RR = 1.54, 95%CI:1.42-1.66, p < 0.00001) and recurrence (n = 446, RR = 0.34, 95%CI:0.20-0.58, p < 0.00001) between the combination of CG with second-generation non-sedated antihistamine and antihistamine monotherapy. Contrastingly, adverse events rate (n = 2317, RR = 0.76, 95% CI:0.59-0.97, p = 0.03) was comparable between the two groups. Our results indicated that CG combined with second-generation non-sedated antihistamine could significantly mitigate the symptoms in CU compared with antihistamine monotherapy. No serious adverse events were reported. CONCLUSIONS: CG combined with second-generation nonsedated antihistamine is effective for CU. Nevertheless, higher-quality studies are warranted to validate our results.

Allergic Rhinitis.

Allergic rhinitis (AR) affects more than 400 million people worldwide, making it 1 of the most prevalent chronic diseases. Childhood AR is increasing, and almost half of patients with AR develop symptoms before age 6 years. Although a diagnosis of AR is associated with higher socioeconomic status, underserved and urban populations have more indoor aeroallergen sensitizations and are likely underdiagnosed with AR, further exacerbating health-care disparities. AR negatively impacts quality of life, school performance, and overall health outcomes. Untreated AR in children increases the risk for poor asthma control, increased asthma severity, and exacerbations. Many patients believe that they have seasonal allergies only but in reality have both perennial and seasonal AR, which may change the approach to allergen avoidance measures and treatment recommendations. Pharmacotherapy of AR has expanded, with many intranasal corticosteroids, intranasal antihistamines, and second-generation oral antihistamines approved for pediatric use. Allergen immunotherapy, including both subcutaneous and sublingual forms, are approved for children and are disease modifying, potentially reducing further allergen sensitization and progression to asthma. Many of the currently available biological therapies indicated for pediatric asthma and/or atopic diseases reduce AR symptoms as well. Children with moderate to severe or refractory AR or those with comorbidities should be referred to allergists for diagnostic testing and expanded management options, including immunotherapy and potential biological treatment.

An international Delphi study on the burden of allergic rhinoconjunctivitis and urticaria and the role of bilastine among current treatment options.

BACKGROUND: Allergic rhinoconjunctivitis and chronic urticaria are common histamine-driven diseases, exerting detrimental effects on cognitive functions, sleep, daily activities, and quality of life. Non-sedating second-generation H1-antihistamines are the first-line treatment of choice. Aim of the study was to define the role of bilastine among second-generation H1-antihistamines in the treatment of allergic rhinoconjunctivitis and urticaria in patients of different ages. METHODS: An international Delphi study was carried out to assess consensus among experts from 17 European and extra-European countries on three main topics: 1) Burden of disease; 2) Current treatment options; 3) Specific characteristics of bilastine among second-generation antihistamines. RESULTS: Here, we present the results obtained for a selection of 15 out of 27 consensus statements, focused on disease burden, role of second-generation antihistamines and bilastine profile. The rate of concordance was ≥98% for 4 statements, ≥ 96% for 6, ≥ 94% for 3, and ≥90% for 2. CONCLUSIONS: The high degree of agreement obtained suggests a wide awareness of the burden of allergic rhinoconjunctivitis and chronic urticaria among experts from all over the world and reflects a broad consensus on the role of second-generation antihistamines in general and of bilastine in particular for their management.

S3 Guideline Urticaria. Part 2: Treatment of urticaria - German-language adaptation of the international S3 guideline.

This publication is the second part of the German-language S3 guideline on urticaria. It covers the management of urticaria and should be used together with Part 1 of the guideline on classification and diagnosis. This publication was prepared according to the criteria of the AWMF on the basis of the international English-language S3 guideline with special consideration of health system conditions in German-speaking countries. Chronic urticaria has a high impact on the quality of life and daily activities of patients. Therefore, if causal factors cannot be eliminated, effective symptomatic treatment is necessary. The recommended first-line treatment is to administer new generation, non-sedating H1 antihistamines. If the standard dose is not sufficiently effective, the dose should be increased up to fourfold. For patients who do not respond to this treatment, the second-line treatment in addition to antihistamines in the treatment algorithm is omalizumab and, if this treatment fails, ciclosporin. Other low-evidence therapeutic agents should only be used if all treatments in the treatment algorithm agreed upon by the guideline group fail. Both the benefit-risk profile and cost should be considered. Corticosteroids are not recommended for long-term treatment due to their inevitable severe side effects.

Current and future management of chronic spontaneous urticaria and chronic inducible urticaria.

Background: Chronic urticaria (CU), characterized by ≥6 weeks of intense pruritus, remains a debilitating condition for patients. New and safe treatments are needed to manage CU recalcitrant to standard therapy. Objective: A review of the current literature of standard and novel therapeutics in the management of CU was conducted. Methods: A literature search via a medical literature data base and clinical trial data base was conducted to identify treatment options for CU and current clinical trials. Results: Second-generation antihistamines, omalizumab, and cyclosporine remain the most proven therapeutic options for CU. Dupilumab, mepolizumab, benralizumab, tezepelumab, and CDX-0159 are all undergoing clinical trials for CU. Although ligelizumab demonstrated initial promising results, a phase III study was discontinued due to a nonsuperior clinical impact compared with omalizumab. Conclusion: Novel therapies are needed for the treatment of recalcitrant CU. With a deeper understanding of the pathophysiology of CU, promising therapeutics are in clinical trials for CU.

Clinical experience of a specialized urticaria outpatient clinic from a Portuguese UCARE.

Summary: Background. Chronic urticaria (CU) is a frequent disease, with a prevalence of at least 1%. It is characterized by pruritic wheals, angioedema or both for a period longer than 6 weeks. Objective. Identify the demographic, clinical, laboratory and therapeutic profile of patients treated in a Portuguese Urticaria Center of Reference and Excellence (UCARE) and compare it with international series. Methods. Retrospective analysis of database of patients observed in a specialized urticaria outpatient clinic, from January 2017 through September 2019, of a UCARE center in Portugal. Demographic and clinical features, laboratory findings and pharmacological treatment were obtained from the records. Descriptive analyses were performed for all variables. Chi square and fisher's exact tests were applied to analyze the independence of variables and the fit of distribution. P less than 0.05 was considered significant. Results. During this period, 477 patients were observed, of whom 429 (90%) were diagnosed with chronic urticaria. Mean age (years) at the onset of symptoms was 43.7 (standard deviation (SD) 17.6, range 6-88) and at diagnosis 46.7 (SD 17.8, range 6-88) resulting in an average diagnostic delay of 3 years (range 0-25). Median follow-up period since first attendance in the specialized outpatient clinic was 1.7 years (interquartile range (IQR) 0.79, range 0.1-2.75) . Concerning the whole group of CU patients, 347 (81%) had chronic spontaneous urticaria (CSU) - 79% female, 39 (9%) had isolated chronic inducible urticaria (CIndU) and 43 (10%) had CSU with CIndU. Autologous serum skin test (ASST) was done in 76 patients (positive in 24 (32%)) and basophil activation test (BAT) was done in 38 (positive in 13 (34%)). At the moment of study, 204 (48%) of CU patients were medicated with a second-generation H1-antihistamine (sgAH) daily (first-line therapy), 99 (23%) with sgAH up to four times the standard dose (second-line therapy) and 126 (29%) with omalizumab (third-line therapy). Additionally, 7 (2%) patients were completing a short course of systemic corticosteroids for management of disease exacerbation. Disease control was achieved in 316 of CSU patients (81%). Conclusions. Referral to a specialized urticaria outpatient clinic is important for a proper assessment of the disease and adequately symptom control.

An evaluation of remission rates with first and second line treatments and indicators of antihistamine refractoriness in chronic urticaria.

BACKGROUND: Guidelines recommend standard doses of antihistamines as first-line, and updosing of antihistamines as second-line treatment for the management of chronic urticaria (CU). However, remission rates with different types of first- and second-line treatments and indicators of antihistamine response are largely lacking in the literature. OBJECTIVES: To examine response rates to first- and second-line treatments in CU, and to identify patient characteristics that can predict antihistamine treatment outcomes. METHODS: We retrospectively analyzed treatment outcomes of 657 CU (556 chronic spontaneous urticaria (CSU), 101 chronic inducible urticaria (CIndU)) patients who had at least 3-months of follow-up data. RESULTS: A standard dose of second generation antihistamines (sgAH) was effective in 43.1 % of the patients. An additional 28.8 % of patients were in remission with second-line treatments. Among patients whose disease was in remission with a standard dose of sgAHs, 14.8 % benefited from switching from their current sgAH to another sgAH. Updosing sgAHs, combination of two different sgAHs, sgAH and first generation H1-antihistamine combination, and sgAH and leukotriene receptor antagonist combination provided remission in 38.3 %, 35.8 %, 37.5 % and 25 % of patients who were given these treatments, respectively. Baseline UCT score ≤ 4, emergency referral and family history of CSU were found to be risk factors for antihistamine refractoriness in patients with CSU. CONCLUSIONS: A step-wise approach to the management of CU is practical as more patients respond to treatment at each step. The presence of baseline UCT score ≤ 4, emergency referral and family history of CSU might be helpful to determine patients who require third-line treatments in advance.

Improving the Quality of Life in the Management of Allergic Rhinitis: New Perspective on Cetirizine.

BACKGROUND: Allergic rhinitis (AR) is associated with disturbed sleep and subsequent functioning, and an impaired quality of life (QoL). The symptoms of AR exhibit prominent circadian variations, with symptoms being more common at the night-time or early morning. Addressing these allergy-related sleep issues, impaired QoL, and circadian variation in symptoms is important from the patient perspective and should be considered in the management of AR. OBJECTIVE: To review the efficacy of cetirizine, a second-generation antihistamine and selective H1-receptor antagonist, in relation to improvement in the QoL of the patients, addressing the sleep disturbances and circadian variations in the symptoms of AR in clinical practice, and establishing its role as a contemporary antihistamine for the management of AR compared to newer antihistamines. METHODS: Systematic literature review of the databases such as PubMed/MEDLINE, Google Scholar, and the Cochrane Central Register of Controlled Trials from 1990 to 2020. RESULTS: The symptoms of AR exhibited a circadian variation, with symptoms being worse during the night and early morning. The patients with AR encountered several sleep-related symptoms, including poor sleep quality, daytime somnolence, fatigue, and impaired productivity and QoL. Impaired QoL in AR was related to the disease severity. Administration of cetirizine at bedtime provides effective control of sleep impairment and symptoms of AR, besides improving the QoL. The efficacy of cetirizine has been demonstrated to be superior or comparable to the newer second-generation antihistamines. Cetirizine exhibits a tolerability profile comparable to the newer antihistamines. CONCLUSION: With long years of clinical experience and a good tolerability profile, cetirizine represents a valuable therapeutic option for the management of AR, even 30 years after its introduction. Cetirizine is included in the National List of Essential Medicines of India for the management of allergic disorders in view of its established efficacy and safety profile as well as being a cost-effective option.

The Impact of Bilastine on Symptoms of Allergic Rhinitis and Chronic Urticaria: A Systematic Review and Meta-Analysis of Randomized Controlled Trials.

BACKGROUND: Allergic diseases are immunological exaggerations with symptoms that may interfere with life quality. Bilastine, a novel oral second-generation H-1 antihistamine, is highly selective to H-1 receptors and has anti inflammatory properties. The present evidence regarding the drug efficacy is inconsistent. OBJECTIVES: We aimed to evaluate the efficacy and safety of bilastine compared with the placebo and other active antihistamines in patients who complained either from AR or chronic urticaria. METHODS: We systematically searched the Medline, Scopus, Web of Science, and Cochrane databases for randomized controlled trials (RCTs) evaluating bilastine effects on symptomatic hyper histaminic allergic conditions. We collected data on total symptoms scores (TSS), total nasal symptom scores (TNSS), discomfort associated with these allergic conditions measured by visual analog score (VAS), and quality of life (QOL) for AR and urticaria. Other outcomes such as clinical global impression and safety profiles were reported as well. We pooled the studies in a random effect model using RevMan 5.4 software. RESULTS: We included 9 RCTs comprising 3801 participants. The meta-analysis revealed that bilastine was superior to placebo, improving TSS, TNSS, VAS, and QOL in AR or chronic urticaria participants. Moreover, the bilastine was comparable to active antihistamines such as cetirizine, fexofenadine, and loratadine regarding mentioned outcomes. In addition, the novel drug was safe and tolerable with no difference in the incidence of adverse events with a placebo. CONCLUSIONS: Bilastine safely improved TSS in hyper histaminic allergic conditions involving nasal symptoms in AR. It decreases the discomfort associated with the disease resulting in improving the QOL of the participants.

How bilastine is used to treat allergic rhinitis and urticaria in children.

Management guidelines for allergic rhinitis and urticaria recommend oral second-generation antihistamines as first-line treatment. The efficacy and safety of bilastine, the newest nonsedating second-generation antihistamine, are well established in adolescents/adults with these allergic conditions. The bilastine development program for pediatric use (2-<12 years) followed EMA-authorized processes. Pharmacokinetic/pharmacodynamic simulation and modeling and a pharmacokinetic study were conducted to identify and confirm the pediatric dose (10 mg/day). A Phase III, multicenter, double-blind, randomized, placebo-controlled, parallel-group study was performed to confirm the safety of bilastine 10 mg/day in children. In this article, evidence is reviewed for use of bilastine in children with allergic rhinoconjunctivitis or urticaria. Several cases are presented which demonstrate its role in routine clinical practice.

Risk factors of uncontrolled symptoms using the standard dose of second-generation H1 -antihistamines in chronic spontaneous urticaria children.

BACKGROUND: A standard dose of second-generation H1 -antihistamines is recommended as the first-line treatment of chronic spontaneous urticaria (CSU), previous studies have found that approximately 20-50% of CSU children fail to control their symptoms and required step-up treatments. OBJECTIVE: To evaluate the predictors of uncontrolled symptoms with first-line medication and describe the treatment outcomes of CSU children in the southern region of Thailand. METHODS: This retrospective chart review of CSU patients, aged 2-18 years, who were initially treated with the standard dose of second-generation H1 -antihistamine at the Pediatric Allergy Clinic, Songkhlanagarind Hospital, from January 2008 to July 2018. The data were collected at the initial visit (demographic data, onset of rash, frequency of urticaria, presence of angioedema, previous resolved CU, laboratory investigation results) and follow-up visits (treatment outcome, time to controlled urticaria). RESULTS: The medical records of 192 CSU children were reviewed; their median age were 8.5 years and the mean frequency of rash was 4 days/week. Forty-seven children (24.4%) fail to controlled symptoms with a standard dose of second -generation H1 -antihistamines and a factor significantly associated was frequency of rash for more than 4 days per week (OR = 4.36, P < 0.001). The median time to controlled urticaria was 1.28 months. CONCLUSIONS: Most of CSU children in the southern region of Thailand experienced controlled symptoms with a standard dose of second-generation H1 -antihistamines, and the frequency of urticaria for more than 4 days per week was a factor associated with uncontrolled symptoms that regimen.

Levocetirizine and montelukast in the COVID-19 treatment paradigm.

Levocetirizine, a third-generation antihistamine, and montelukast, a leukotriene receptor antagonist, exhibit remarkable synergistic anti-inflammatory activity across a spectrum of signaling proteins, cell adhesion molecules, and leukocytes. By targeting cellular protein activity, they are uniquely positioned to treat the symptoms of COVID-19. Clinical data to date with an associated six-month follow-up, suggests the combination therapy may prevent the progression of the disease from mild to moderate to severe, as well as prevent/treat many of the aspects of 'Long COVID,' thereby cost effectively reducing both morbidity and mortality. To investigate patient outcomes, 53 consecutive COVID-19 test (+) cases (ages 3-90) from a well-established, single-center practice in Boston, Massachusetts, between March - November 2020, were treated with levocetirizine and montelukast in addition to then existing protocols [2]. The data set was retrospectively reviewed. Thirty-four cases were considered mild (64%), 17 moderate (32%), and 2 (4%) severe. Several patients presented with significant comorbidities (obesity: n = 22, 41%; diabetes: n = 10, 19%; hypertension: n = 24, 45%). Among the cohort there were no exclusions, no intubations, and no deaths. The pilot study in Massachusetts encompassed the first COVID-19 wave which peaked on April 23, 2020 as well as the ascending portion of the second wave in the fall. During this period the average weekly COVID-19 case mortality rate (confirmed deaths/confirmed cases) varied considerably between 1 and 7.5% [37]. FDA has approved a multicenter, randomized, placebo-controlled, Phase 2 clinical trial design, replete with electronic diaries and laboratory metrics to explore scientific questions not addressed herein.

Urticaria and edema in a 2-year-old boy.

The absence of blisters, the presence of mild systemic symptoms, and the patient's age guided the diagnosis.

Assessment of receptor affinities of ophthalmic and systemic agents in dry eye disease.

PURPOSE OF REVIEW: To explore our current understanding of receptor profiles acted upon by medications used to treat dry eye disease (DED). RECENT FINDINGS: Research into histaminic and muscarinic receptor affinities for drugs targeting the ocular surface has not kept up with bench research pertaining to the receptor profile of the ocular surface. These insights are necessary for better evaluation of medications used in DED and other allergic disorders. SUMMARY: At the H1 receptor, Ketotifen (pKa = 9.2), pyrilamine (pKa = 9.0), and epinastine (pKa = 8.0) had the highest affinities, whereas ranitidine (pKa = 4.2) and cimetidine (pKa = 4.9) had the lowest. Ketotifen, a second-generation antihistamine, was found to have a pKa of 6.7 at muscarinic receptors which was higher than that of diphenhydramine (pKa = 6.4), a first-generation antihistamine. Additionally, second-generation antihistamines have higher affinity for H3 receptors, which have been linked to urticaria, compared to first-generation. Azelastine, a second-generation, demonstrated significant affinity (pKa = 7.1) at the H3 receptor compared to all other drugs. Antazoline (pKa = 4.4) and diphenhydramine (pKa = 4.6), both first-generation antihistamines, had the lowest affinities for the H3 receptor. These findings raise questions about the use of antihistamines in the treatment of DED and allergic disorders.

Síndrome DRESS por paracetamol / DRESS syndrome due to acetaminophen

A síndrome DRESS é uma entidade rara e distinta, caracterizada por acometimento cutâneo e envolvimento de órgãos internos, com risco potencial de morte. O diagnóstico e o tratamento pre- coces são de vital importância. Relatos de DRESS por paraceta- mol são raros na literatura, razão pela qual apresentamos este caso. Paciente do sexo masculino, 56 anos, com surgimento de rash maculopapular, febre, linfadenopatia e hipereosinofilia 3 semanas após suspensão de paracetamol, associados ao ante- cedente familiar de reação a fármaco. Evoluiu bem após pulso- terapia com metilprednisolona.

DRESS syndrome is a rare and distinct entity characterized by cutaneous manifestations and internal organs involvement with a potential risk of death. Early diagnosis and treatment are vi- tally important. Reported cases of DRESS syndrome due to ace- taminophen are rare in the literature, and that is the reason for this case report. A 56-year-old male patient with maculopapular rash, fever, lymphadenopathy, and hypereosinophilia three we- eks after suspension of acetaminophen, associated with a family history of drug reaction. It progressed well after pulse therapy with methylprednisolone.

Targeted Use of Placebo Effects Decreases Experimental Itch in Atopic Dermatitis Patients: A Randomized Controlled Trial.

Evidence from pain research shows that the effectiveness of active pharmacological treatments can be enhanced by placebo effects. The "open drug administration" is superior to "hidden drug administration.​" In a randomized controlled trial, we aimed to show that the targeted use of placebo effects increases the efficacy of an antihistamine (dimetindene) infusion in participants with atopic dermatitis. We openly infused dimetindene (drug) in full sight with information (intervention group 1: OPEN-DRUG+INST), openly infused drug with an additional classical conditioning learning experience (intervention group 2: OPEN-DRUG+INST+COND) or infused drug without any information or sight (i.e., hidden administration (control group 1: HIDDEN-DRUG)). Control group 2 received a placebo infusion (saline) declared as dimetindene and also experienced the conditioning experience (PLAC+INST+COND). Itch was experimentally induced with histamine via a skin prick test. Outcome was assessed at the subjective (primary end point: experimental itch intensity, numeric rating scale), and objective level (secondary end point: wheal size, mm2 ). Experimental-induced itch intensity decreased in all groups but at different rates (P < 0.001). The groups with the open administration, whether it was dimetindene or placebo, had significantly stronger reductions in itch compared to the HIDDEN-DRUG group (OPEN-DRUG+INST+COND: P < 0.001; OPEN-DRUG+INST: P = 0.009; and PLAC+INST+COND: P < 0.001). Additional drug conditioning mediated via expectation led to a stronger reduction of itching (P = 0.001). Results on wheal size were similar (P = 0.048), however, no significant difference between the HIDDEN-DRUG group and the PLAC+INST+COND group (P = 0.967) was found. We conclude that specifically generated targeted placebo effects can significantly increase the action of a drug (dimetindene) and should be used in clinical practice.

Eosinophilic cystitis mimicking bladder cancer-considerations on the management based upon a case report and a review of the literature.

The hypereosinophilic syndrome (HES) is a rare disorder characterized by hypereosinophilia and infiltration of various organs with eosinophils. Eosinophilic cystitis (EC), mimicking bladder cancer clinically but also in ultrasound and in radiographic imaging, is one potential manifestation of the HES occurring in adults as well as in children. This case report describes the course of disease in a 57-year-old male presenting with severe gait disorders and symptoms of a low compliance bladder caused by a large retropubic tumor. After extensive urine and serologic examination and histologic confirmation of EC the patient was subjected to medical treatment with cetirizine and prednisolone for 5 weeks. While gait disorders rapidly resolved, micturition normalized only 10 months after initiation of therapy. Based upon this course the authors recommend patience and reluctance concerning radical surgical intervention in EC. Key Points • Eosinophilic cystitis is a rare condition with app. 200 cases reported, so far. • Etiology of eosinophilic cystitis is obscure, but allergies and parasitic infections may trigger the disease. • Genetic alterations (e.g., BRAF mutations) may predispose for the disease • Corticosteroids and antihistamines are the backbone of therapy and may be complemented by antibiotics and non-steroidal anti-inflammatory drugs in case of concomitant (underlying) infections. • As recovery can occur even after a long time, radical surgery should be restricted to highly selected cases.

Antiallergic drug desloratadine as a selective antagonist of 5HT2A receptor ameliorates pathology of Alzheimer's disease model mice by improving microglial dysfunction.

Alzheimer's disease (AD) is a progressively neurodegenerative disease characterized by cognitive deficits and alteration of personality and behavior. As yet, there is no efficient treatment for AD. 5HT2A receptor (5HT2A R) is a subtype of 5HT2 receptor belonging to the serotonin receptor family, and its antagonists have been clinically used as antipsychotics to relieve psychopathy. Here, we discovered that clinically first-line antiallergic drug desloratadine (DLT) functioned as a selective antagonist of 5HT2A R and efficiently ameliorated pathology of APP/PS1 mice. The underlying mechanism has been intensively investigated by assay against APP/PS1 mice with selective 5HT2A R knockdown in the brain treated by adeno-associated virus (AAV)-ePHP-si-5HT2A R. DLT reduced amyloid plaque deposition by promoting microglial Aß phagocytosis and degradation, and ameliorated innate immune response by polarizing microglia to an anti-inflammatory phenotype. It stimulated autophagy process and repressed neuroinflammation through 5HT2A R/cAMP/PKA/CREB/Sirt1 pathway, and activated glucocorticoid receptor (GR) nuclear translocation to upregulate the transcriptions of phagocytic receptors TLR2 and TLR4 in response to microglial phagocytosis stimulation. Together, our work has highly supported that 5HT2A R antagonism might be a promising therapeutic strategy for AD and highlighted the potential of DLT in the treatment of this disease.