How would i know if this is allergies or cold?

Duration of symptoms: The common cold will last 5-7 days. Allergies will last days, weeks, months, or years and timing is by seasons or exposures. With allergies there is more itching, sneezing and the runny nose is clear. With allergies, frequently there is eye itching, watery or redness. Allergies respond to antihistamines such as zyrtec, claritin, (loratadine) allegra, etc and colds don't.