Common side effects include headache, sleepiness, change in taste, and sore throat.[8] It is unclear if use is safe duringpregnancy orbreastfeeding.[9] It is a second-generationantihistamine and works by blocking the release of a number ofinflammatory mediators includinghistamine.[7][8]
Azelastine was patented in 1971 and came into medical use in 1986.[10] It is available as ageneric medication.[4][11] In 2023, it was the 142nd most commonly prescribed medication in the United States, with more than 3million prescriptions.[12][13]
Azelastine is safe and well tolerated in both adults and children withallergic rhinitis.[17][18][19] Bitter taste, headache, nasal burning andsomnolence are the most frequently reported adverse events. US prescribing recommendations warn against the concurrent use of alcohol and/or other central nervous system depressants, but to date there have been no studies to assess the effects of azelastine nasal spray on the CNS in humans[needs update?]. More recent studies[20][21] have shown similar degrees ofsomnolence (approx. 2%) compared with placebo treatment.
The most common side effect is a bitter taste (about 20% of people). Due to this, the manufacturer has produced another formulation of azelastine withsucralose.[22] The problem of bitter taste may also be reduced by correct application of the nasal spray (i.e. slightly tipping the head forward and not inhaling the medication too deeply), or alternatively using the azelastine/sucralose formulation.[23]
In addition,anosmia (loss in the ability to smell) can occur with nasal spray antihistamines (including both formulations of azelastine).[medical citation needed]
The systemicbioavailability of azelastine is approximately 40% when administered intranasally. Maximum plasma concentrations (Cmax) are observed within 2–3 hours. Theelimination half life is 22 h, the steady-statevolume of distribution is 14.5 L/kg, and the plasma clearance is 0.5 L/h/kg (based on intravenous and oral administration data). Approximately 75% of an oral dose is excreted in feces.Pharmacokinetics of orally administered azelastine is not affected by age, gender, or hepatic impairment.[24]
Azelastine is oxidatively metabolized by thecytochrome P450 family into its active metabolite, desmethylazelastine, and two inactive carboxylic acid metabolites.[24]
The chemical nomenclature of azelastine is (±)-1-(2H)-phthalazinone, 4-[(4-chlorophenyl) methyl]-2-(hexahydro-1-methyl-1H-azepin-4-yl)-monohydrochloride. It is white, almost odorless with a bitter taste.[25]
An ophthalmic drop formulation of azelastine (Optivar) was approved by the US FDA in 2000.[27] Prescription nasal spray formulations were approved in 1996 (Astelin) and 2008 (Astepro),[28] with Astepro becoming available over‑the‑counter in 2021.[29]
Azelastine may have in vitro antiviral activity against respiratory viruses, includingSARS-CoV-2.[30][31][32] It is thought to work by interfering with the interaction of the SARS-CoV-2spike glycoprotein andACE2 by fixing the receptor in a closed form.[30] In 2025, a small single-center phase II randomized trial found reduced incidence ofPCR-confirmed SARS-CoV-2 infection, increased mean time to infection, and reduced PCR-confirmedrhinovirus infections by two thirds, without adverse effects.[33]
^Bousquet J, Schünemann HJ, Togias A, Bachert C, Erhola M, Hellings PW, et al. (January 2020). "Next-generation Allergic Rhinitis and Its Impact on Asthma (ARIA) guidelines for allergic rhinitis based on Grading of Recommendations Assessment, Development and Evaluation (GRADE) and real-world evidence".The Journal of Allergy and Clinical Immunology.145 (1): 70–80.e3.doi:10.1016/j.jaci.2019.06.049.hdl:10400.17/3723.PMID31627910.
^Ratner PH, Findlay SR, Hampel F, van Bavel J, Widlitz MD, Freitag JJ (November 1994). "A double-blind, controlled trial to assess the safety and efficacy of azelastine nasal spray in seasonal allergic rhinitis".The Journal of Allergy and Clinical Immunology.94 (5):818–25.doi:10.1016/0091-6749(94)90148-1.PMID7963150.
^LaForce C, Dockhorn RJ, Prenner BM, et al. (February 1996). "Safety and efficacy of azelastine nasal spray (Astelin NS) for seasonal allergic rhinitis: a 4-week comparative multicenter trial".Annals of Allergy, Asthma & Immunology.76 (2):181–8.doi:10.1016/S1081-1206(10)63420-5.PMID8595539.
^Corren J, Storms W, Bernstein J, Berger W, Nayak A, Sacks H (May 2005). "Effectiveness of azelastine nasal spray compared with oral cetirizine in patients with seasonal allergic rhinitis".Clinical Therapeutics.27 (5):543–53.doi:10.1016/j.clinthera.2005.04.012.PMID15978303.
^Berger W, Hampel F, Bernstein J, Shah S, Sacks H, Meltzer EO (September 2006). "Impact of azelastine nasal spray on symptoms and quality of life compared with cetirizine oral tablets in patients with seasonal allergic rhinitis".Annals of Allergy, Asthma & Immunology.97 (3):375–81.doi:10.1016/S1081-1206(10)60804-6.PMID17042145.
^Kalpaklioglu AF, Kavut AB (2010). "Comparison of azelastine versus triamcinolone nasal spray in allergic and nonallergic rhinitis".American Journal of Rhinology & Allergy.24 (1):29–33.doi:10.2500/ajra.2010.24.3423.PMID20109317.S2CID24449860.
^Bernstein JA (October 2007). "Azelastine hydrochloride: a review of pharmacology, pharmacokinetics, clinical efficacy and tolerability".Current Medical Research and Opinion.23 (10):2441–52.doi:10.1185/030079907X226302.PMID17723160.S2CID25827650.
^abcHorak F, Zieglmayer UP (November 2009). "Azelastine nasal spray for the treatment of allergic and nonallergic rhinitis".Expert Review of Clinical Immunology.5 (6):659–669.doi:10.1586/eci.09.38.PMID20477689.S2CID32512061.
^Spangler DL, Bensch G, Berdy GJ (August 2001). "Evaluation of the efficacy of olopatadine hydrochloride 0.1% ophthalmic solution and azelastine hydrochloride 0.05% ophthalmic solution in the conjunctival allergen challenge model".Clinical Therapeutics.23 (8):1272–80.doi:10.1016/s0149-2918(01)80106-5.PMID11558863.
^Kaliner MA, Berger WE, Ratner PH, Siegel CJ (February 2011). "The efficacy of intranasal antihistamines in the treatment of allergic rhinitis".Annals of Allergy, Asthma & Immunology.106 (2 Suppl):S6 –S11.doi:10.1016/j.anai.2010.08.010.PMID21277531.
