Have you had an allergic reaction to something that you have been exposed to bef!

Have you had an allergic reaction to something that you have been exposed to before and NOT had a reaction to?

My daughter has hives all over her body. I took her to her Dr. who said it is definately an allergic reaction, gave her medicine and it is going away. The problem is that I can't figure out what she is allergic to. We have not had anything new. There is a couple things that she has eaten before but not for a while, that she had again. I gave her a bagel that has seeds in it - sesame, poppy and sunflower. She has had them before but months ago and no reaction. Could that be it?

Or (which I posted in another question) could it be red dye from some tylenol I gave her? She has had red dye in Tylenol brand cold medicine before and not had a reaction. I normally give her grape flavored tylenol for fevers and teething. But I ran out and my Dr. gave me another brand of prescription acetaminophen that has Red dye #33 and Red dye #40 in it.

She has had medicine and food with red dye in it before.

Can she still have an allergic reaction to something she has had before?

Red dye is a common food allergy. My daughter is allergic to it! Even though you have been exposed to something many times, sometimes even for years, allergies may develop this suddenly. A precaution for you and your daughter--now that she has had one reaction, future allergic reactions, no matter what they are to, may be more severe to the point of anaphylaxis. Drug manufacturers do make dye-free medications; always choose those. Please also consider asking your daughter's physician for an Epi-Pen to be used in case of anaphylaxis.