Managing Seasonal Allergies

The management of seasonal allergies includes avoidance of the allergen(s) and pharmacotherapy.1 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 Nonpharmacologic measures 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, etc).3 Choose a medication based on severity of symptoms, patient age, other medical conditions, and preferences.2 Alternative therapies (e.g., supplements, homeopathy, and acupuncture) have been used and promoted for seasonal allergies; however, there are insufficient data to recommend these therapies.3,4


Consider for…

Avoid or use particular caution…

Nasal corticosteroids

See our chart, Nasal Sprays for Allergic Rhinitis (U.S.) (Canada)

First-line for moderate to severe, persistent symptoms.3,5

Nasal congestion.3,5

Itchy, irritated, or watery eyes.3


  • 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 at the end of this chart.

First-line for mild or intermittent symptoms (second generation).3,5

Itching, sneezing, rhinorrhea (second generation).5

Under two years (most second generation).9,14

  • Under 12 years (fexofenadine [Canada only]).14

Elderly, risk of excessive sedation (first generation, cetirizine).9

Risk for decreased cognition or motor skills (first generation).9

Glaucoma (first generation).9,14

Severe liver impairment.9

Severe renal impairment (cetirizine, desloratadine, rupatadine [Canada]).9,14

With moderate or strong CYP3A4 inhibitors, grapefruit juice (rupatadine [Canada]).14

With orange, grapefruit, apple juice; other OATP inhibitors (fexofenadine).7

Prolonged QT interval (Canada: bilastine, rupatadine).14

Nasal antihistamines

Add-on therapy with nasal steroids, if needed (especially for nasal congestion).1,3,8

Under five years (azelastine).9

Under six years (olopatadine).9

Neither 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 [U.S.]).9

Decongestants (intranasal, oral)

Inadequate response from a nasal steroid for nasal congestion.2

Use in combination with an oral antihistamine (intranasal).3

Intermittent nasal congestion.2

Hypertension, arrhythmia, coronary heart disease, hyperthyroidism, glaucoma, diabetes, and benign prostatic hypertrophy (oral).2

Prolonged use (more than three to five days) (intranasal).2,3

With monoamine oxidase inhibitors.6

Monotherapy (intranasal).6

Cromolyn (intranasal [U.S.])


Inadequate response with other treatments.

Children when parents have safety concerns with other therapy.6

Children under two years.9

Leukotriene receptor antagonists (Montelukast)

Use as a last resort.10

Use if coexisting asthma.1

For seasonal allergic rhinitis: under two years (U.S.), under 15 years (Canada).17,18

Anxiety, depression, and psychiatric disorders.6

Oral corticosteroids

Use if severe rhinitis symptoms prevent sleep and/or work (last resort).6

Prolonged use (more than a few days).6


Second-generation antihistamines are often recommended over first-generation antihistamines as they are as effective and have less sedation or other adverse effects.11-13

First-Generation Antihistamines

Second-Generation Antihistamines

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, etc).

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 others).

Can be more expensive than first-generation antihistamines.

Project Leader in preparation of this clinical resource (360404): Annette Murray, BScPharm


  1. 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;119:489-511.
  2. Sur DK, Plesa ML. Treatment of allergic rhinitis. Am Fam Physician 2015;92:985-92.
  3. Small P, Keith PK, Kim H. Allergic rhinitis. Allergy Asthma Clin Immunol 2018;14 (Suppl 2):51.
  4. Brinkhaus B, Ortiz M, Witt CM, et al. Acupuncture in patients with seasonal allergic rhinitis: a randomized trial. Ann Intern Med 2013;158:225-34.
  5. Seidman MD, Gurgel RK, Lin SY, et al. Clinical practice guideline: allergic rhinitis. Otolaryngol Head Neck Surg 2015;152 (1Suppl):S1-43.
  6. deShazo RD, Kemp SF. Pharmacotherapy of allergic rhinitis. Last updated April 8, 2018. In UpToDate, Post TW (ed), UpToDate, Waltham, MA 02013.
  7. Bailey DG. Fruit juice inhibition of uptake transport: a new type of food-drug interaction. Br J Clin Pharmacol 2010;70:645-55.
  8. 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;167:876-81.
  9. Clinical Pharmacology powered by ClinicalKey. Tampa (FL): Elsevier. 2020. (Accessed March 12, 2020).
  10. 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 4, 2020. (Accessed March 12, 2020).
  11. 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;15:61.
  12. Church MK, Church DS. Pharmacology of antihistamines. Indian J Dermatol 2013;58:219-24.
  13. Wang XY, Lim-Jurado M, Prepageran N, et al. Treatment of allergic rhinitis and urticaria: a review of the newest antihistamine bilastine. Ther Clin Risk Manag 2016;12:585-97.
  14. eCPS [Internet]. Ottawa (ON): Canadian Pharmacists Association; c2020. (Accessed March 20, 2020).
  15. Product monograph for Zaditor. Aurium Pharma. Concord, ON L4K 4X3. February 2012.
  16. Product monograph for Patanol. Novartis. Dorval, QC H9S 1A9. March 2018.
  17. Product information for Singulair. Merck Sharp & Dohme. Whitehouse Station, NJ 08889. February 2019.
  18. Product monograph for Singulair. Merck Canada. Kirkland, QC H9H 4M7. April 2019.

Cite this document as follows: Clinical Resource, Managing Seasonal Allergies. Pharmacist’s Letter/Prescriber’s Letter. April 2020.

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