Pharmacological therapy
Anticholinergics
Example drug: Ipratropium bromide
Anticholinergics work by blocking the muscarinicreceptors of the seromucinous glands. They effectively control wateryrhinorrhea but do not affect sneezing or nasal congestion, which precludes theiruse as a first-line medication. They may be used together with intranasalcorticosteroids or antihistamines in patients in whom rhinorrhea is thepredominant symptom, or in whom rhinorrhea does not respond well to the othermedications.
Antihistamines
H1-receptor antagonists reduce nasalitching, sneezing, and rhinorrhea, but are less effective for nasal obstruction.They are considered as first-line treatment for mild-moderate intermittent andmild persistent rhinitis. They are added to intranasal corticosteroids formoderate-severe persistent rhinitis with eye symptoms uncontrolled byintranasal corticosteroid monotherapy.
Nasal Antihistamines
Example drugs: Azelastine, Levocabastine,Olopatadine
Nasal antihistamines have a rapid onset of action(<15-30 minutes). They are recommended in patients with seasonal, perennial,or episodic allergic rhinitis. They are also recommended as a first-line optionfor patients with intermittent allergic rhinitis. They are the preferredtreatment for allergic rhinitis when compared to intranasal cromones. They areassociated with a significant effect on nasal congestion.
They are considered effective at the site ofadministration and may be used for mild, organ-limited disease or as an “asrequired” medication used together with a continuous one. They are as effectiveas oral antihistamines but they require twice-daily dosing.
Oral Antihistamines
Oral antihistamines have the advantage of relievingother allergic symptoms of other sites (eg conjunctivitis) along with nasalsymptoms. They may be used to prevent symptoms associated with occasionalallergy exposure. They are preferred over leukotriene receptor antagonists (LTRA)in patients with moderate-severe perennial allergic rhinitis.
Second-generation antihistamines are preferred overintranasal antihistamines. The use of first-generation antihistamines should belimited as they may reduce academic ability in school children and may produceperformance impairment in adults while driving. They have an onset of action thatoccurs within 1 hour.
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Second-generation OralAntihistamines
Exampledrugs: Bilastine, Cetirizine, Desloratadine, Fexofenadine, Levocetirizine,Loratadine, Mequitazine, Rupatadine
Second-generation oral antihistamines should beconsidered as a first-choice treatment and are preferred over first-generationoral antihistamines. They have less undesirable central nervous system (CNS)and fewer anticholinergic effects compared to first-generation antihistamines.They have little or no sedative effect at the recommended dosages.
First-generation OralAntihistamines
Example drugs: Chlorpheniramine, Clemastine,Diphenhydramine
The use of first-generation antihistamines islimited by their sedative and anticholinergic side effects and short half-life.They may further impair cognitive functioning and school performance inchildren.
Intraocular Antihistamines
Intraocular antihistamines may be used in patients withsymptoms of ocular involvement (eg conjunctivitis).
Anti-IgE Antibody
Example drug: Omalizumab
Omalizumab has been shown to be effective inreducing nasal symptoms and improving quality of life in patients with seasonalallergic rhinitis.
CorticosteroidsCorticosteroids have a strong anti-inflammatorycapacity by reducing cytokine and chemokine release.
Intranasal Corticosteroids
Example drugs: Beclomethasone, Budesonide,Ciclesonide, Flunisolide, Fluticasone, Mometasone, Triamcinolone
Intranasal corticosteroids are more efficacious thanoral or topical nasal antihistamines in relieving symptoms of allergicrhinitis, especially nasal obstruction.
They are considered first-line treatment in patientswith moderate-severe and/or persistent symptoms. They are preferred overintranasal and oral antihistamines in patients with moderate-severe perennialor seasonal allergic rhinitis. Monotherapy with intranasal steroids ispreferred over a combination with oral antihistamines for patients with perennialallergic rhinitis. Combination therapy with intranasal antihistamines is moreeffective than monotherapy with intranasal steroids in patients with moderate-severedisease.
In severe cases, nasal corticosteroids should bestarted 2 weeks before the start of the pollen season, then given regularly.
The onset of action takes a few hours (6-12 hours)to a few days, with maximum efficacy developing after two weeks. Aqueouspreparations are preferred because they are less irritating to the nasal mucosa.Studies have shown reassuring safety data of Fluticasone, Mometasone, andCiclesonide use on the long-term growth of children. They are generally notassociated with clinically significant systemic side effects if given inrecommended doses.
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Systemic Corticosteroids
Systemic corticosteroids may be used in rareconditions in severe patients unresponsive to other treatments and areintolerant to intranasal corticosteroids. Prednisolone or Methylprednisoloneshould be administered in a short period of time (5-7 days).
Cromones (Nasal)
Nasal cromones are less effective thanantihistamines and intranasal corticosteroids. Compliance is often poor becauseof the need for frequent administration. They may be considered in symptomatictreatment (nasopharyngeal itchiness, sneezing, rhinorrhea) to be given prior toallergen exposure. Intraocular cromones may be considered for the management ofocular symptoms (eg conjunctivitis).
Cromones have an excellent safety profile that maymake them a suitable option for children and pregnant women.
Decongestants
Decongestants promote vasoconstriction by acting onadrenergic receptors, thus relieving swelling of the nasal mucosa.
Nasal Decongestants
Example drugs: Oxymetazoline, Xylometazoline
Nasal decongestants are very effective in relievingnasal obstruction and rhinorrhea. Because of the risk of rebound vasodilation(rhinitis medicamentosa) and atrophic rhinitis with prolonged use, their useshould be limited to 3-5 days. Short courses may be used to immediately reducesevere nasal obstruction while giving other medications for allergic rhinitis (egintranasal corticosteroid-decongestant combination). They may be added tointranasal corticosteroid or intranasal corticosteroid/antihistaminecombination therapy for four weeks in patients with persistent nasal congestion.
Oral Decongestants
Example drugs: Ephedrine, Pseudoephedrine
Oral decongestants have a weaker effect on nasalobstruction than topical preparations but do not cause rebound vasodilatation. Theyhelp relieve nasal obstruction, rhinorrhea, and ocular symptoms. Their use maybe considered in patients with severe allergic rhinitis who are unresponsive tooral antihistamines and intranasal corticosteroids. Their use should be limiteddue to known adverse effects (insomnia, agitation, palpitation).
Leukotriene Receptor Antagonists(LTRA)
Example drugs: Montelukast, Pranlukast, Zafirlukast
The efficacy of LTRA is similar to oralantihistamines for patients with seasonal allergic rhinitis. They help relievesneezing and rhinorrhea and reduce eosinophilic infiltration and nasalsecretion. It is a therapeutic option used either alone or in combination withantihistamines but should not be used as initial therapy. It should only beconsidered in patients with treatment failure or intolerance to first-linetherapy. They are also preferred in patients with coexisting asthma. There is areduction in beta-agonist use with the administration of Montelukast.
Saline Solutions
Saline solutions may be used as single or adjunctiveagents in reducing the symptoms of allergic rhinitis. There is no difference inthe radiologic or symptomatic score when comparing isotonic with hypertonicsaline, although hypertonic solutions have been shown to improve mucociliaryclearance.
Immunotherapy
Immunotherapy is recommended for patients with moderate or severe persistent allergic rhinitis with inadequate response to the usual pharmacologic therapy and allergen avoidance measures under the supervision of a specialist or allergist.
Subcutaneous Immunotherapy (SCIT)
The indications of SCIT include inadequate control with medications, patient refusal to receive pharmacotherapy or to undergo treatment on a long-term basis, and intolerable or unacceptable adverse effects from medications.
SCIT should be considered in patients with seasonal allergic rhinitis due to pollens and perennial allergic rhinitis triggered by house dust mites. The efficacy of SCIT for allergic rhinitis is comparable to that of nasal glucocorticoids. However, it is limited by frequent injections on a regular basis and the small risk of an anaphylactic reaction.
Sublingual Immunotherapy (SLIT)
SLIT should be considered in patients with allergic rhinitis triggered by house dust mites and grass or ragweed pollen, regardless of whether the patient has asthma. It is considered a more viable treatment compared to SCIT as self-administration is encouraged with this form. Its use should be limited to those who can tolerate systemic reactions and its treatment. It has been associated with mild oral and gastrointestinal (GI) symptoms; however, it has less risk for anaphylaxis compared to SCIT.
AlternativeTherapies
A variety of herbal preparations and honey have been suggested forallergic rhinitis but there is lack of sufficient evidence to support thisrecommendation. St. John’s wort may decrease the effectiveness ofantihistamines, while Echinacea purpurea may cause anaphylaxis in atopicpatients.
