Allergic rhinitis (AR) is a common inflammatory disease that affects 10 to 25% of the population worldwide [1]. Patients with AR experience a decreased quality of life associated with typical AR symptoms (i.e., sneezing, pruritus, nasal obstruction, and rhinor- rhoea) and issues such as smell-taste disorders, halitosis, fatigue, malaise, and possible neurocognitive deficits [2,3].
Halitosis is an unpleasant, offensive odour spreading from the oral cavity and is commonly known as ‘bad breath’. It is a very com- mon complaint among patients who visit otolaryngology clinics. When severe or long-standing, it may lead to personal discom- fort and social embarrassment, thus impacting the quality of life in a negative manner. The causative agents of halitosis are the oral cavity (90%), the respiratory tract (8%), and the gastrointesti- nal tract, including other organs (2%) [3]. Halitosis associated with the oronasal cavity may be due to post-nasal drip, pharyngitis, ton- sillitis, deep crypts of the tonsils, sinusitis, a foreign body in the nasal or sinus cavity, and ozena. These pathologies cause halito- sis because of bacteria, which cause putrefaction of the tissues and