Sinus infections are usually characterized by the following symptoms:
Nasal congestion, drainage of yellowish or greenish discharge, and headaches around the frontal part of the face and below the eyes.  Sinus infections may also be related with allergies, as anything that causes blockage in the nose will back up into the sinuses causing infection. 

Acute sinus infections may come on suddenly and are frequently associated with a cold or sometimes a change in atmospheric pressure.  This will cause acute symptoms usually characterized with headaches around the sinuses as well as marked nasal congestion.  Occasionally, over-the-counter sinus decongestions will help these conditions, but frequently may require a visit to the doctor for a prescription for antibiotics.

Chronic sinus infections tend to be lingering symptoms to include nasal congestion, nasal drainage, and occasional sneezing, which can be associated with allergies.  These symptoms tend to be lingering and long-lasting and have less acute symptoms and are less painful.  There may also be a sensation of chronic postnasal drainage and clearing of the throat.  This may require further evaluation with x-ray studies as well as allergy evaluations and further medical treatment.