Sneezing is caused by anything that irritates the lining of the nasal passages. These causes can vary from allergens to infection to dental disease to cancer. Occasional sneezing in any cat is normal. However, Dr. Radke finds that if your cat is sneezing excessively, then there probably is an underlying problem that should be addressed. Young cats are prone to upper respiratory infections and nasopharyngeal polyps (benign growths in the nasal passages). Older cats can also be prone to infections but are more likely to have dental disease or cancer as the cause of their sneezing.