How do you know if it's an allergic reaction?

[melon1]

DD has eczema which is pretty much under control at the moment -when it started at 2 months she did have some on her face but that cleared up pretty quickly and she hasn't had any there for months - recently she's started to develop a red rash round her mouth when she eats anything tomatoey - could this be the eczema? Teething? The eczema on her body hasn't flated up, just around her mouth - is this an allergic reaction or just sensitive skin?

[tatt]

sorry had to dash away earlier but wanted to reply. The short answer is its really hard (see post about husband and egg ) Try putting tomato on her arm or back to see if that goes red, if it does its probably allergy. Tomatoes are quite a common allergen. You need skin prick and blood tests to be sure.