How long before you see an allergic reaction to new meds?

Haley

My 10 month old was diagnosed with an ear infection today. The pediatrician prescribed amoxicillin, which makes me nervous since our friend’s baby had a severe reaction to it - eyes swollen shut, rash all over his body. I’m also allergic to it as well. How long does it take to notice if your baby is allergic to this medication?