Hello @robino001, Welcome to Mayo Clinic Connect! Thank you for posting! I can understand your concern!
Have you talked with your sons pediatrician about this? Is there another type of antihistamine that his primary would be willing to have you try besides Allegra?
Here is a link to what Mayo Clinic has to offer on information for cold induced uticaria- https://www.mayoclinic.org/diseases-conditions/cold-urticaria/basics/treatment/con-20034524.
Also, I read on the link above that the other things you can do to help prevent a recurrent episode of cold urticaria:
•Take an over-the-counter antihistamine before cold exposure.
•Take medications as prescribed.
•Protect your skin from the cold or sudden changes in temperature. For example, wear a wetsuit when swimming in cold water. Some people have had success with this method, but it isn’t proved.
•Avoid ice-cold drinks and food to prevent swelling of your throat.
•If your doctor prescribed an epinephrine autoinjector (Epipen, Auvi-Q, others), keep it with you to help prevent serious reactions.
•If you’re scheduled for surgery, talk with your surgeon beforehand about your cold urticaria. The surgical team can take steps to help prevent cold-induced symptoms in the operating room.
I did see that another member, @jewel8888, has also talked about cold induced uticaria. I’ve tagged Jewel here hoping that she is willing to share her experiences with you, or maybe share some tips on how symptoms were personally handled.