What Is Sinusitis?

Sinusitis is a swelling of the inner lining of the sinuses. The swelling blocks the openings in the sinuses through which mucus drains into the nose. When mucus cannot drain properly, the pressure of the blocked fluid inside the sinuses can be painful. Acute sinusitis is usually due to the common cold, while chronic sinusitis is mostly caused by allergies or fungus, or by bacteria or a virus.

Common symptoms include a stuffy or runny nose, clear, thin discharge from the nose (as in chronic sinusitis), or thick yellow of green discharge from the nose, sometimes tinged with blood (as in acute sinusitis), sneezing and/or coughing, pain over the bridge of the nose and a headache that is worse in the morning and when bending forward an altered sense of smell and/or taste and bad breath.