Hi, I Haven't Taken Antibiotics In Many Years And Today

Hi, I haven't taken antibiotics in many years and today got a prescription for Azithromycin also know as zithromax. When my son (now 29) was about 8 he took zithromax and had an allergic reaction which included uncontrolled itching and had to go to the ER. they told us it was not possible to be allergic to zithromax. Now I see on the insert that there can be allergic reactions. Should I be worried to take it? I don't have a history of allergies, but this year I developed hay fever for the first time in my life.