an allergic reaction is often sudden hives that are very pruritic (itchy). an amoxicillin side effect usually occurs near the end of the course of treatment (day 8-10 not day three) and is bright red occuring all over the body. this does not usually itch. so. it could be either one. i don't have enough specific information and the ability to examine your baby to offer you a definitive answer.
is breaking out in a rash a side effect of amoxicillin or an allergic reaction. my 8 month old broke out in a rash after 3 days of using amoxicillin for an ear infection. doctor said it was a side effect i just want to make sure cause my sister has a high allergy to amoxicillin.