This is a phase 4 study to evaluate the the efficacy of second generation antihistamine on cough outcomes in cough patients with allergic rhinitis.

This is a randomized, double blind, placebo controlled trial in which a total of 78 participants who have cough (≥ 3 weeks) and symptoms of allergic rhinitis will be enrolled. Study participants will be randomly assigned to either active treatment or placebo group. The subjects in active treatment groups will be treated with daily oral bepotastine for 2 weeks, while those in placebo group will take identical-looking tablets. The efficacy of bepotastine will be assessed at the end of 2-week intervention using leicester cough questionnaire.

Inclusion Criteria:

1. Had a cough for at least 3 weeks (score of ≥30 mm on the VAS)
2. History or allergic rhinitis confirmed with skin prick test or serum specific IgE test AND current one or more symptoms of allergic rhinitis (runny nose, obstruction, sneezing, nasal itching)
3. Provided written informed consent
4. Were willing and able to comply with the study protocol

Exclusion Criteria:

1. Current smoker or individuals who have smoked within the past 1 month prior to study entry
2. Sings of coexisting respiratory diseases requiring active treatment such as fever, chills, wheezing, dyspnea, or purulent sputum
3. Currently under allergen immunotherapy
4. 1) Allergic rhinitis or chronic rhinosinusitis under treatment with intranasal corticosteroids (INS) or leukotriene receptor antagonist (LTRA) or 2) allergic rhinitis requiring treatment with INS or LTRA
5. Treatment with an angiotensin converting enzyme (ACE)-inhibitor within 4 weeks prior to the enrollment
6. Forced Expiratory Volume in 1 second (FEV1)/Forced Vital Capacity (FVC) < 0.7 or FEV1 % of predicted < 80% within 1 month prior to enrollment
7. Abnormal findings on chest x-ray related to cough within 1 month prior to enrollment
8. Diagnosis or treatment of bronchial asthma or COPD within 1 year of the enrollment
9. Clinically significant medical conditions possibly affecting evaluation of cough and nasal symptoms
10. History of hypersensitivity or severe adverse reaction to antihistamines
11. Unable to fill in the questionnaires (blindness, unable to read)
12. Unable to provide informed consent
13. History of taking following medication within 2 weeks of the enrollment; LTRA, nasal decongestants, intranasal corticosteroids (INS), systemic corticosteroids, antitussive agents (OTCs, codeine)

Allocation of medication is conducted by an independent physician who is not a co-investigator of the study.