colds are caused by viruses. the only biological explanation in your case would be that your allergies are overwhelming your immune system making you more vulnerable to getting a viral infection. allergies cause congestion and inflammation and respiratory viruses tend to be opportunisitic. hitting you when you are down so to speak. there are no direct relationship between colds and allergies otherwise but a person can certainly have both at the same time.
most of the time when i get cold it's triggered by my allergies. is this normal? what can i do to prevent this? . i laid over freshly cut grass (usually an allergy trigger) in 20 minutes the allergies kicked in. sneezing runny nose watery eyes. went home to take an otc allergy med. the medicine didn't seem to work as it usually did. (i have very manageable seasonal allergies). that night i has a full blown cold. fever chills body aches terrible sore throat. . for year i have seen the same pattern. . not all my allergies trigger a cold but most of my colds are triggered by simple allergies.