Symptoms of nasal polyps include a rotten smell in your nose or a dramatically decreased sense of smell and taste. Nasal polyps tend to be very small, so you may not even know you have them.

Do nasal polyps cause bad breath?

Sinus issues such as sinus infections, postnasal drip and nasal polyps are also a common reason for halitosis because they facilitate the buildup of odor-causing bacteria in your nose and sinus cavities.

Why do nasal polyps smell bad?

The bad smell that accompanies nasal polyps may be due to fluid buildup inside the polyps. The fluid comes from the damp lining of your mucous membrane, which helps moisten your respiratory tract and trap dust and other foreign substances from reaching your lungs.