Do you get a skin rash or stomachache after eating a tomato? You could have a tomato allergy. According to a 2018 study, true tomato allergies occur in around 1.5% of people from Northern Europe.
However, tomato allergies also occur due to oral allergy syndrome (OAS), a lipid transfer protein (LTP) allergy, or a nightshade allergy.
This guide covers everything you need to know to understand and manage a tomato allergy, including key symptoms, diagnostic tests, and helpful advice.
What is a Tomato Allergy?
Tomato allergies might sound straightforward. It’s an immune reaction caused by eating tomatoes. Like other reactions, it’s triggered because your body wrongly identifies the tomato as a threat, launching an immune defence.
It’s not that simple, however. There are several potential underlying causes behind a tomato allergy, including:
- True Tomato Allergy. This is a type 1 hypersensitivity reaction (or a contact allergy). When your body comes into contact with tomatoes, histamines are released, causing an allergic reaction. Sometimes, people with this allergy have a cross-reaction to latex (latex-fruit syndrome).
- Nightshade Allergy. Nightshades are a group of plants, including potatoes, aubergines, tomatoes, chilis, and more, that contain chemical compounds called alkaloids. Some people are allergic to alkaloids, producing an allergic reaction.
- Oral Allergy Syndrome (OAS). People who are allergic to pollen can have a cross-reaction allergy to certain fruits, including tomatoes, peaches, celery, melons, or potatoes. Usually, this allergy only affects the raw version of the fruit.
- Lipid Transfer Protein (LTP) Allergy. Newly identified in 2019, it is caused by the presence of LTP found in foods like tomatoes, nuts, seeds, and cereals. It can occur with both the raw and cooked versions of the food.
In addition, some people also have a tomato intolerance. Unlike an allergic reaction, it won’t cause an acute immune response but can lead to irritation and discomfort due to the acidity of the tomato.
Tomato Allergy Symptoms
True tomato allergies elicit an immune reaction. The severity of this reaction will differ from person to person. However, in the most severe cases, it can cause anaphylaxis, where a person can go into shock and even die. You should seek immediate medical attention.
People can experience the following symptoms:
- Hives or welts
- Itchy rashes
- Eczema
- Nausea
- Vomiting
- Diarrhoea
- Sneezing
- Runny or stuffy nose
- Itching or tingling in the mouth
- Swelling of the lips, tongue, or throat
In oral allergy syndrome, the symptoms are usually milder and briefer. Nonetheless, the two conditions can appear similar. Symptoms include:
- Itching in the mouth, lips, or throat
- Swelling of the lips, tongue, or throat
- Tingling in the mouth or throat
- Redness or mild rash around the mouth or chin
- A sensation of tightness in the throat
- Watery or itchy eyes
- Runny or stuffy nose
- Sneezing
- Nausea
Foods to Avoid
Ever since South American explorers first brought back tomatoes from the New World, they’ve become a mainstay of world cuisine. It’s not just pasta sauces. You’ll find tomatoes in British dishes like tomato soup, Mexican cuisine, Hungarian goulash, and, of course, several Indian curries. Tomatoes are everywhere!
Unfortunately, because of the relative rarity of tomato allergies, they’re not one of the main 14 allergens. That means they’re not highlighted in bold in ingredient lists or restaurant menus.
When eating out, always speak to restaurant staff and scour the ingredients list for any sign of tomatoes. Here are some specific foods to avoid:
- Tomato Sauce: Used in pasta dishes, pizza, and other Italian cuisines.
- Ketchup: Common condiment for fries, burgers, and other fast foods.
- Salsa: Often contains tomatoes, used in Mexican and Tex-Mex cuisines.
- Chilli: Many chilli recipes include tomatoes.
- Tomato Soup: A classic soup made primarily from tomatoes.
- Tomato Juice: Used in beverages and as a cooking ingredient.
- Marinara Sauce: Similar to tomato sauce, used in various pasta dishes.
- Barbecue Sauce: Some recipes include tomato or ketchup.
- Gazpacho: A cold soup made from raw, blended vegetables, often tomato-based.
- V8 or other Vegetable Juices: These often contain tomato juice as a primary ingredient.
Diagnosing and Managing a Tomato Allergy
Identifying a tomato allergy can be challenging, as symptoms may overlap with other allergies or intolerances. Plus, as mentioned, you may cross-react to other ingredients and items, complicating the diagnosis.
Usually, diagnosis involves a combination of these tests:
- Skin Prick Test: This test involves placing a small amount of tomato allergen on your skin, usually on the forearm, and then gently pricking the skin. If you’re allergic, a raised bump or hive will appear.
- IgE Blood Test: An IgE blood test can measure the immune system’s response to tomatoes by checking the level of certain antibodies in your bloodstream.
- Elimination Diet: This involves removing tomatoes and tomato-based products from your diet for a period, then reintroducing them to see if symptoms return.
- Oral Food Challenge: Conducted under medical supervision, this test involves consuming small amounts of tomato to observe for any allergic reactions.
The only successful management strategy is to eliminate tomatoes from your diet. If your allergy is mild, taking an over-the-counter antihistamine can alleviate symptoms if you plan to eat tomatoes. However, for severe allergies, carrying an adrenaline auto-injector (like an EpiPen) can prevent anaphylaxis should the worst happen.
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