The symptoms of a tomato allergy include eczema or hives, stomach cramps, vomiting, and facial swelling, according to Healthline. Other symptoms sometimes occur, such as diarrhea, itchy throat, sneezing, wheezing or a runny nose. In rare cases the patient experiences anaphylaxis, a severe reaction that potentially causes death.
Patients with eczema experience outbreaks of the rash when exposed to tomatoes. The eczema usually develops instantly after they are exposed. Patients sometimes experience repeated rashes with severe itching and inflammation, notes Healthline. To diagnose the allergy a health care professional tests the patient's blood. Doctors prescribe antihistamines to treat tomato allergies and steroid-based ointments relieve the rash.