A systematic review and meta-analyses depicted that after monotherapy with antihistamines fails to alleviate symptoms, adding decongestant, saline, or leukotriene receptor antagonist (LTRA) can lead to better outcomes. When monotherapy with intranasal corticosteroids is not effective, adding intranasal antihistamines can lead to improvements in nasal symptoms; LTRA can improve ocular symptoms, and saline irrigation can enhance the patient's quality of life.

Researchers undertook this study to determine additional effects of different medical combinations when compared to primary therapies for allergic rhinitis. Databases like EMBASE and Pubmed were searched to find out relevant randomized controlled trials that compared the impact of combinations with monotherapy.

Notably, there were 7 comparisons: (a) Antihistamines-decongestant vs antihistamines, (b) Antihistamines-LTRA vs antihistamines, (c) Intranasal corticosteroids-antihistamines vs intranasal corticosteroids, (d) Intranasal corticosteroids-LTRA vs intranasal corticosteroids, (e) Intranasal corticosteroids-decongestion vs intranasal corticosteroids, (f) Intranasal corticosteroids-saline irrigation vs intranasal corticosteroids, and (g) Antihistamines-saline irrigation vs antihistamines.

For performing the meta-analysis, pooling of data was done. Quality of life, composite nasal symptom score, adverse events, and composite ocular symptom score were the outcomes ascertained. A total of 53 studies were incorporated. When compared to antihistamines alone, the antihistamines-decongestant combination improved composite nasal symptoms; antihistamines-LTRA improved nasal symptoms in people having perennial allergic rhinitis; antihistamines-nasal saline improved both symptoms and quality of life of the patient.

In comparison with intranasal corticosteroids alone, the combination of intranasal corticosteroids-intranasal antihistamines led to improvements in nasal symptoms, ocular symptoms and quality of life; intranasal corticosteroids-LTRA alleviated ocular symptoms but not nasal symptoms; intranasal corticosteroids-nasal saline improved patient's quality of life but not symptoms. No additional effects were noted from the addition of oral antihistamines or topical decongestants to intranasal corticosteroids.