Managing Seasonal Allergies

full update April 2025

Nonpharmacologic management of seasonal allergies include nasal irrigation and allergen avoidance (e.g., keeping windows closed, using window screen filters and air conditioning, limiting outdoor time during peak allergen season, showering after outdoor exposure).³ Choose a medication based on severity of symptoms, patient age, other medical conditions, and preferences.² Immunotherapy (subcutaneous or sublingual) can be considered if other management is not adequate or if the patient has seasonal allergies in combination with asthma.^1,2 Alternative therapies (e.g., supplements, homeopathy, acupuncture, honey) have been used and promoted for seasonal allergies; however, there are insufficient data to recommend these therapies.^3,4

Drug/Class	Consider for…	Avoid or use particular caution…
Nasal corticosteroids See our chart, Nasal Sprays for Allergic Rhinitis.	first-line for moderate to severe, persistent symptoms.^3,5 nasal congestion.^3,5 itchy, irritated, or watery eyes.³	in children:^9,14 under six years (budesonide). under four years (fluticasone propionate). under two years (triamcinolone, mometasone [three years in Canada], fluticasone furoate).
Oral antihistamines See our comparison of first- and second-generation antihistamines later in this document.	first-line for mild or intermittent symptoms (second generation).^3,5 itching, sneezing, rhinorrhea (second generation).⁵	under two years (most secondgeneration).^9,22 under 12 years (fexofenadine [Canada only]).¹² in older adults, risk of excessive sedation (first generation, cetirizine).⁹ due to risk for decreased cognition or motor skills (first generation).⁹ with glaucoma (first generation).⁹ if severe liver impairment.⁹ if moderate to severe kidney impairment.^9,13 with moderate or strong CYP3A4 inhibitors, grapefruit juice.^9,13 with orange or apple juice; other OATP inhibitors (fexofenadine).⁹ if prolonged QT interval (Canada:bilastine, rupatadine).^7,13
Nasal antihistamines See our chart, Nasal Sprays for Allergic Rhinitis.	add-on therapy with nasal steroids, if needed (especially for nasal congestion, rhinorrhea).^1,3,8	in children: under two years (azelastine 0.1% by prescription only [US]).⁹ under six years (azelastine 0.15% [US], olopatadine [US]).⁹ under five years (azelastine 0.1% [US]).⁹ (note: not available as single-ingredient nasal sprays in Canada).
Ophthalmic antihistamines	add-on therapy for eye symptoms with nasal steroids, if needed.¹	under three years (ketotifen, olopatadine [Canada]).^9,15,16 under two years (olopatadine [US]).⁹
Decongestants (intranasal, oral)	inadequate response from a nasal steroid for nasal congestion.² use intranasal in combination with an oral antihistamine.³ intermittent nasal congestion.²	if hypertension, arrhythmia, coronary heart disease, hyperthyroidism, glaucoma, diabetes, and benign prostatic hypertrophy (oral).² prolonged use of intranasal (more than three to five days).^2,3 with monoamine oxidase inhibitors.⁶ as monotherapy (intranasal).⁶ oral phenylephrine due to lack of efficacy.²³
Cromolyn (intranasal [US]) See our chart, Nasal Sprays for Allergic Rhinitis.	prevention. inadequate response with other treatments. children when parents have safety concerns with other therapy.⁶	under two years.⁹
Leukotriene receptor antagonists (montelukast)	use as a last resort.^6,10 use if coexisting asthma.¹	for seasonal allergic rhinitis:under two years (US), under 15 years (Canada).^17,18 if anxiety, depression, and psychiatric disorders.⁶
Oral corticosteroids	use as a last resort for severe symptoms.^6,20,21	prolonged use (more than a few days).^6,20,21

Comparison of First- and Second-Generation Antihistamines. Second-generation antihistamines are often recommended over first-generation antihistamines as they are as effective for seasonal allergies and have less sedation or other adverse effects.^11,19

First-Generation Antihistamines^11,19

Second-Generation Antihistamines^11,19

Some examples of first-generation antihistamines include: brompheniramine, chlorpheniramine, diphenhydramine, doxylamine, hydroxyzine

Non-selective (target histamine-1 receptors, but also cholinergic, alpha-adrenergic, and serotonergic receptors).
Can have substantial adverse effects, especially in older patients (not recommended in patients >65 years old).
Most common adverse effect is sedation.May decrease cognitive and motor skills, use with caution.
Some (especially children) may have stimulating effects
(e.g., insomnia, anxiety, hallucinations).
Can cause anticholinergic effects (e.g., dry mouth, dry eyes, constipation, tachycardia).

Some examples of second-generation antihistamines include:
- bilastine (Canada only)
- cetirizine
- desloratadine
- fexofenadine
- loratadine
- rupatadine (Canada only)
Selective (more specific to peripheral histamine-1 receptors; don’t cross the blood-brain barrier).
Generally well tolerated.
Generally not sedating (note that cetirizine may be slightly more sedating than other second generation antihistamines).
Can be more expensive than first-generation antihistamines.

Levels of Evidence

In accordance with our goal of providing Evidence-Based information, we are citing the LEVEL OF EVIDENCE for the clinical recommendations we publish.

Level	Definition	Study Quality
A	Good-quality patient-oriented evidence.*	High-quality randomized controlled trial (RCT) Systematic review (SR)/Meta-analysis of RCTs with consistent findings All-or-none study
B	Inconsistent or limited-quality patient-oriented evidence.*	Lower-quality RCT SR/Meta-analysis with low-quality clinical trials or of studies with inconsistent findings Cohort study Case control study
C	Consensus; usual practice; expert opinion; disease-oriented evidence (e.g., physiologic or surrogate endpoints); case series for studies of diagnosis, treatment, prevention, or screening.

*Outcomes that matter to patients (e.g., morbidity, mortality, symptom improvement, quality of life).

[Adapted from Ebell MH, Siwek J, Weiss BD, et al. Strength of Recommendation Taxonomy (SORT): a patient-centered approach to grading evidence in the medical literature. Am Fam Physician 2004;69:548-56. https://www.aafp.org/pubs/afp/issues/2004/0201/p548.html.]

References

Dykewicz MS, Wallace DV, Baroody F, et al. Treatment of seasonal allergic rhinitis: An evidence-based focused 2017 guideline update. Ann Allergy Asthma Immunol. 2017 Dec;119(6):489-511.
Hauk L. Treatment of Seasonal Allergic Rhinitis: A Guideline from the AAAAI/ACAAI Joint Task Force on Practice Parameters. Am Fam Physician. 2018 Jun 1;97(11):756-757.
Small P, Keith PK, Kim H. Allergic rhinitis. Allergy Asthma Clin Immunol. 2018 Sep 12;14(Suppl 2):51.
Brinkhaus B, Ortiz M, Witt CM, et al. Acupuncture in patients with seasonal allergic rhinitis: a randomized trial. Ann Intern Med. 2013 Feb 19;158(4):225-34.
Seidman MD, Gurgel RK, Lin SY, et al. Clinical practice guideline: Allergic rhinitis. Otolaryngol Head Neck Surg. 2015 Feb;152(1 Suppl):S1-43.
deShazo RD, Kemp SF. Pharmacotherapy of allergic rhinitis. January 2025. In UpToDate, Post TW (ed), UpToDate, Waltham, MA 02013.
Product monograph for Blexten. Aralez Pharmaceuticals Canada. Mississauga ON L5N 6J5. August 2021.
Wallace DV, Dykewicz MS, Oppenheimer J, et al. Pharmacologic Treatment of Seasonal Allergic Rhinitis: Synopsis of Guidance From the 2017 Joint Task Force on Practice Parameters. Ann Intern Med. 2017 Dec 19;167(12):876-881. Erratum in: Ann Intern Med. 2018 May 15;168(10):756.
Clinical Pharmacology powered by ClinicalKey. Tampa (FL): Elsevier. 2025. http://www.clinicalkey.com. (Accessed February 28, 2025).
FDA. FDA requires boxed warnings about serious mental health side effects for asthma and allergy drug montelukast (Singulair); advises restricting use for allergic rhinitis. March 13, 2020. https://www.fda.gov/drugs/drug-safety-and-availability/fda-requires-boxed-warning-about-serious-mental-health-side-effects-asthma-and-allergy-drug. (Accessed February 28, 2025).
Fein MN, Fischer DA, O'Keefe AW, Sussman GL. CSACI position statement: Newer generation H1-antihistamines are safer than first-generation H1-antihistamines and should be the first-line antihistamines for the treatment of allergic rhinitis and urticaria. Allergy Asthma Clin Immunol. 2019 Oct 1;15:61.
Product monograph for Allegra. Sanofi Consumer Health. Laval QC H7V 0A3. October 2021.
Product monograph for Rupall. Medexus. Bolton ON L7E1K1. January 2023.
eCPS [Internet]. Ottawa (ON): Canadian Pharmacists Association; c2025. Corticosteroids: eye, ear, nose. September 1, 2018. http://www.e-therapeutics.ca. (Accessed February 28, 2025).
eCPS [Internet]. Ottawa (ON): Canadian Pharmacists Association; c2025. http://www.e-therapeutics.ca. (Accessed February 28, 2025).
Product monograph for Patanol. Novartis. Dorval, QC H9S 1A9. March 2018.
Product information for Singulair. Organon. Jersey City, NJ 07032. February 2021.
Product monograph for Singulair. Organon Canada. Kirkland, QC H9H 4M7. May 2021.
American Academy of Family Physicians. Clinical practice guideline: allergic rhinitis. Reaffirmed April 2020. https://www.aafp.org/family-physician/patient-care/clinical-recommendations/all-clinical-recommendations/allergic-rhinitis.html. (Accessed February 28, 2025).
Hox V, Lourijsen E, Jordens A, et al. Benefits and harm of systemic steroids for short- and long-term use in rhinitis and rhinosinusitis: an EAACI position paper. Clin Transl Allergy. 2020 Jan 3;10:1. Erratum in: Clin Transl Allergy. 2020 Sep 28;10:38.
May JR, Dolen WK. Management of allergic rhinitis: a review for the community pharmacist. Clinical Therapeutics. November 2017. https://www.clinicaltherapeutics.com/article/S0149-2918(17)31006-8/pdf. (Accessed February 28, 2025).
Chu DK, Oykhman P, Sussman GL. How to use antihistamines. CMAJ. 2021 Apr 6;193(14):E478-E479.
FDA. Key information about nonprescription, over-the-counter (OTC), oral phenylephrine. November 7, 2024. https://www.fda.gov/drugs/understanding-over-counter-medicines/key-information-about-nonprescription-over-counter-otc-oral-phenylephrine. (Accessed March 18, 2025).

Cite this document as follows:Clinical Resource, Managing Seasonal Allergies.Pharmacist’s Letter/Pharmacy Technician’s Letter/Prescriber Insights. April 2025. [410468]

Managing Seasonal Allergies

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