I have written a article on this health condition. https://hubpages.com/health/Is-it-a-cold-or-allerg... Usually, if the mucus is clear its allergy, or cold. If it lasts for more than a week its allergy. If its green or yellow-bacteria and has turned into something more than, just a cold. Colds and allergy, you don't run a fever. With the flu you do run a fever, with aches, pains, cold chills, and tiredness. In my article I have included numerous natural treatments for these health conditions. I hope this helps.