Acute sinusitis usually follows a viral infection in the upper respiratory tract , but allergy-causing substances (allergens) or pollutants may also trigger acute sinusitis. A Viral infection damages the cells of the sinus lining, leading to inflammation. The lining thickens, obstructing the nasal passage. This passage connects to the sinuses. The obstruction disrupts the process that removes bacteria normally present in the nasal passages, and the bacteria begin to multiply and invade the lining of the sinus. This causes the symptoms of sinus infection. Allergens and pollutants produce a similar effect.
Mild nasopharyngeal irritation following the use of beclomethasone aqueous nasal spray has been reported in up to 24% of patients treated, including occasional sneezing attacks (about 4%) occurring immediately following use of the spray. In patients experiencing these symptoms, none had to discontinue treatment. The incidence of transient irritation and sneezing was approximately the same in the group of patients who received placebo in these studies, implying that these complaints may be related to vehicle components of the formulation.