Thankfully, true allergy to tomatoes is rare. Some people have problems with acidic foods like tomatoes and orange juice. Tomatoes are part of the nightshade plant family, so some people will have allergies to them, along with potatoes, eggplant, and other nightshade plant fruits and vegetables.
People who only have digestive upset from eating tomatoes may only have an intolerance, not a true allergy. If you, or your child, develop a rash or hives then it is more likely an allergy.
Babies have notoriously sensitive digestive tracts that may not tolerate tomatoes, and other acidic foods, early in life. There is no suggested age to wait to before introducing them, but if you try a little tomato and your child has any problems hold off for at least a year or two before trying them again.
Some people with tomato allergy problems notice that it only causes a reaction when eaten raw. They find that they can tolerate ketchup, spaghetti sauce and pizza. Cooking can change the allergenic protein in the tomato enough that the body no longer recognizes it as a problem.
Oral Allergy Syndrome
Tomatoes can be involved in oral allergy syndrome. This syndrome is based on a cross reaction between pollen and food proteins that are very similar. Tomatoes are in a group with grass pollen, celery, melons, oranges, and peaches. The immune system recognizes the pollen and proteins in the food and directs an allergic reaction against them. Usually reaction is only to raw foods, as cooking will distort the protein allergens – so that the immune system cannot recognize it.
This syndrome usually starts in a child or adult who has eaten tomatoes in the past without difficulty. Usually symptoms are limited to the mouth and throat–irritation, itching or swelling. Blisters could form in the mouth or around the lips. If the reaction progresses beyond the mouth there is a risk for anaphylaxis, a very serious allergic reaction.
Tomato Allergy Symptoms
Allergy symptoms will usually appear almost immediately after contact with a tomato. Itching and swelling round lips and inside your mouth are the first symptoms. Swelling is noticeable but does not cause difficulties breathing. It will usually disappear as soon as you swallow the tomato and rinse your mouth and lips.
Essentially any area that was touched by the raw tomato can react by forming blisters. A tingling sensation usually signals the start of a blister. It can take up to 30 minutes for blisters to form.
Itching and irritation in your throat is also common. Symptoms will calm down once you drink a glass of water. If you sense that you are starting to have difficulties breathing or your throat is tightening seek medical assistance immediately. Anaphylaxis is rare, but it does happen.
Tomatoes can cause a skin reaction. Localized itching, irritation, or a rash can develop on your face, hands/arms, or abdomen. Some people develop eczema if they ingest them. Others will have only hives develop.
Basically the best thing you can do is avoid tomatoes. Watch out for tomato puree hiding in foods. Experiment a little. Maybe you can eat small amounts of cooked tomatoes, or a slice on a sandwich intermittently. Some people seem to lose their allergy to tomatoes, but it can come back rather suddenly, so always be careful.
Now that you know that reactions to tomatoes, be they allergies or an intolerance, can happen – you can consider if you or a loved one is having a reaction to them. When this happens the best thing to do is avoidance. Anyone at any age can develop problems from eating tomatoes though usually it is an older child or adult problem.