Allergic rhinitis is a hypersensitivity disease of the nasal mucous membrane mediated by immunoglobulin E (IgE), which is characterised by itching, sneezing, watery nasal discharge, and nasal obstruction. Antihistamines have been proven to be highly effective in providing symptomatic relief of allergic diseases. They are competitive blockers of histamine at the H1 receptor.

A study was conducted to compare the efficacy of Chlorpheniramine maleate (first-generation antihistamine) and Fexofenadine (second-generation antihistamine) in patients with allergic rhinitis.

• The mean total symptom score was reduced with both treatments. Patients receiving  Fexofenadine experienced a complete change in median symptoms score, whereas those receiving Chlorpheniramine reported a significant reduction.
• In comparison to Chlorpheniramine, Fexofenadine was found to be relatively more effective in relieving sneezing, nasal obstruction, and nasal discharge- the three main symptoms of allergic rhinitis. Any sedative activity was not documented with the use of Fexofenadine.
• As far as adverse effects are concerned, Fexofenadine is thought to be better tolerated than Chlorpheniramine maleate. 
• Fexofenadine and Chlorpheniramine did not produce any significant impact on absolute eosinophil count (AEC).

Therefore, Fexofenadine is more effective in alleviating the symptoms of allergic rhinitis as compared to Chlorpheniramine. Both the antihistamines had no significant effect on the AEC