superskully
Expert Member
Not always the case.... I have no allergies, we gave up testing to find one (millions of things one can be allergic to). My ENT (and I have had 3 including a specialist surgical ENT), all say some people are just inclined to infections, allergies or not. But if you have not been tested, big ones are dust, pollen and grass.
Depends on the allergy, sinus is usually an irritant.
Carpets, pollution, pollen (seasonal), ..
Though maybe there are other rare cases.