there are many potential mechanisms by which food may cause symptoms. allergic reactions are caused by allergic antibodies leading to immediate hypersensitivity reactions. nut allergy typically causes itching lip/tongue swelling nausea vomiting lightheadedness flushing and/or rash. the rash is usually hives (welts) but some develop other types of skin eruptions. ulcers in the mouth is an unusual manifestation. make a list of all the foods that cause the symptoms timecourse of development of symptoms in relationship to eating the food so your doctor/allergic can further investigate.
when i eat nuts i break out in cold sores canker sores and neck rash. is this a common reaction?