Cold or Allergy? How to Tell the Difference

I get more allergies that look like colds than colds themselves, usually when immune system is down due to stress or just because. I take echinacea and the allergies leave me, that's the prime use I have for it, more than colds. Why would that be? I found that there are some studies that indicate it might cause allergies for children under 12, but not for adults, and even those studies aren't that conclusive. Still, I dont take it daily, but when i see symptoms that my immune system is going down (allergies get stronger).

Alex 10:44PM December 06, 2012