Labels stating "may contain" should list the same 14 allergens as they must for intentional ingredients, for example separating tree nuts and peanuts.
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I am a peanut allergy sufferer but I can eat all other nuts. however, I avoid a large number of products with precautionary allergen labelling as I fear anaphylactic shock if I have a reaction and this is under the guidance of food businesses. But the lack of specific labelling is becoming more common and is making it harder for me to find food I know is 100% safe which is deeply concerning because I feel I should be able to buy more food then I can without worrying and this is widespread.