Sinusitis is a confusing topic, not only for patients but for many health practitioners as well. The confusion arises because of the many facets of this condition, problems with establishing the cause, and similarities between the symptoms of infection and those of allergy. In many cases allergy and infection coexist, feeding on each other, so that the allergic reaction also provides a home for micro-organisms and any infection (and its treatment) can trigger an allergic reaction.