<s>[INST] My daughter vomits for hours after eating fish. We have tried the same type of fish on two separate occasions - the first time she had no reaction to it, the second time she vomited for hours (as has been her reaction to other types of fish in previous experiences). She is now five and a half years old. I did a first aid course this morning and spoke to the nurse about it. She said we should consult a doctor about this as vomiting is not a common allergy reaction. [/INST] Vomiting is an allergic response.  It is an allergy to the iodine in fish and shellfish.  With repeated exposure, the reaction will worsen and may become very dangerous.  A consult with a good allergist in this type of case is helpful.  An epi-pen prescription will be needed for home use.  Consultation should be given regarding avoiding fish, shellfish and foods prepared with them. </s>