Allergies occur when the body's immune system mistakenly identifies a substance, usually a protein, as a threat and reacts accordingly, taking measures to remove the offending substance from the system, resulting in an allergic reaction. Tomato allergies are known as Type 1 contact allergies and are relatively rare. Symptoms can range from mild to life-threatening and can worsen over time. Some people experience adverse reactions to tomatoes without being technically allergic.
Tomato Allergies and Leaf Poisoning
The fruit of the tomato plant is the most common source of allergic reactions, and people with tomato allergies tend to react worst to tomato seeds, skin and juice. Tomato vines and leaves do not seem to induce allergic reactions in people with tomato allergies, though they can be poisonous to anyone when eaten in large quantities. Tomato allergies manifest when the fruit is ingested and do not typically result from handling the fruit or vine, though inhalation of the offending protein might trigger a reaction. Some people with tomato allergies are able to eat processed tomato products such as ketchup, tomato paste and canned tomatoes without experiencing a reaction but react poorly to fresh tomatoes.
Mild to moderate symptoms of tomato allergies include hives, abdominal pain and cramps, skin irritation, nasal inflammation and itching, tingling and/or swelling of the mouth (oral allergy syndrome). Severe reactions are referred to as anaphylaxis with symptoms that include difficulty breathing, changes in skin colour, and swelling of the face and extremities. Consuming the leaves or vine can cause diarrhoea, vomiting, headache and stomach pains. These are poisoning symptoms, not allergic reactions, and can occur regardless of one's sensitivity to the fruit. Severity of symptoms depends on how much material has been ingested.
The first step in diagnoses usually involves a review of medical history and thorough questioning related to diet and symptoms. Your doctor may ask you to keep a food diary to help identify the problematic food. Once the suspected problem has been identified, your doctor may try an elimination diet in which the food is removed from your diet and later reintroduced to observe the results. This method is time-consuming and imprecise and many doctors choose to forgo these steps in favour of clinical testing. Blood and scratch tests ("pricks") are common ways of diagnosing allergies, though false positives can be a problem. An oral food challenge involves the patient consuming small amounts of food allergens under close medical supervision.
Tomatoes are part of the deadly nightshade family. Potatoes are part of the same family, and potato allergies are often concurrent with tomato allergies. Other members of this family include eggplant, peppers and tobacco. Some people respond poorly to tomatoes not because of a specific food allergy but because of a low tolerance for salicylate, a chemical that occurs naturally in many fruits and vegetables and that can be found in aspirin, beauty products and processed foods.
The simplest and most obvious treatment for tomato allergies is to avoid products containing tomatoes and, if necessary, related fruits. Although some people with tomato allergies are able to eat processed tomato products, it is generally recommended that they refrain as allergies can worsen over time. Antihistamines can help control mild acute symptoms. If anaphylatic symptoms are observed, consult a medical professional immediately. In the event of leaf poisoning, treat symptoms and seek medical advice; medical attention may not be necessary.