Sinus allergies vs infection? how can you tell the difference?

Allergy vs infection: If you produce yellow or green nasal discharge then infection is present. Fever is associated with infection. Headache is more likely infection than allergy. Both problems can cause congestion. If symptoms are seasonal then allergy likely. Persistent trouble needs medical work-up.

Symptoms: Allergic nasal symptoms include clear watery secretions, nasal congestion, sneezing and itchy eyes, ears, nose and throat with symptoms lasting the duration of the season, 4 to 6 weeks or longer. Acute sinus infection symptoms include unilateral discolored, foul tasting, foul smelling secretion, congestion, and sinus related pain. The onset is more acute and the duration shorter.