How can you tell the difference between a cold and allergies?

Sometimes difficult: but except in very severe cases of allergy, people don't lose appetite with allergy which is also not associated with a fever. Allergy may also be seasonal. Cold is more common when school starts and in the winter, allergy in the warmer months. Cold is not relieved by antihistamine which does reduce allergic symptoms. Hope these points are helpful.

Difficult: Alot of the symptoms of a cold and allergy overlap. However, allergy does not give a fever and cold will resolve within a week or so.

Cold and allergies: Colds usually come with systemic symptoms of body aches and low grade fever. With allergies you generaly feel well except for your nasal symptoms.