Is there a way to know if i have a common cold or allergies?

Duration of symptoms: While allergies can last days, weeks, months or years, the common cold last 5-7 days. With allergies, there is more itching, sneezing and runny nose is clear. Frequently there is eye redness, itching and watering with allergies. Antihistamines like zyrtec, allegra, Claritin (loratadine) relieve symptoms of allergies, but not colds. There may be fever with colds, but none with allergies.

Timing: If cold occurs only during certain time of year or related to a specific exposure it is allergy.