What Is an Allergic Reaction to Tomatoes?

An allergic reaction to tomatoes is often the result of oral allergy syndrome, according to the National Institute of Allergy and Infectious Diseases. The institute says hay fever sufferers are most at risk from the syndrome due to a cross-reactivity between plant proteins and similar proteins found in fruits and vegetables. The Children's Hospital of Philadelphia says symptoms mainly occur at the point of contact and include swollen lips, blisters in your mouth or throat, and itching or irritation to the affected area. Other parts of the body can display symptoms if the reaction is not due to oral allergy syndrome.

An allergic reaction to tomatoes happens almost immediately after coming in contact with a tomato. Itching and swelling inside or around your lips is one of the first symptoms to develop. The swelling is temporary and lasts as long as the tomato remains in contact with your lips. Remove or swallow the tomato and rinse your mouth and lips with clean water to help reduce the swelling. If you have oral allergy syndrome, you may also display a similar allergic reaction to other fruits and vegetables.

Blisters may develop inside your mouth if you are allergic to tomatoes. Areas directly exposed to tomato flesh, juice, skin or seeds can flare up in the form of a blister or lesion. A tingling sensation is a warning sign that a blister is about to form. The University of Michigan's Annie Khuntia, M.D., and Andrew Singer, M.D., say symptoms can occur immediately or up to 30 minutes after exposure. Blisters and lesions subside once you swallow the tomato or remove it from your mouth and rinse away any remaining juices.

Mild itching and irritation in your throat from a tomato allergy is common and usually nothing to worry about. Symptoms are short-lived and calm down if you remove the tomato from your mouth and drink a glass of water. According to a study by researchers at the Medical College of Wisconsin, reactions to tomato allergies are rarely serious. However, if you have difficulty breathing, feel your throat tighten or experience a whole-body reaction to tomatoes, seek medical help immediately or dial 911 as it could be an early sign of anaphylaxis, a potentially life-threatening condition.

Oral allergy symptoms are restricted to the mouth area, but if you have an allergic reaction to tomatoes without a pre-existing cross-reactivity with pollen, you may have a reaction in another part of your body. If you are allergic to tomatoes and your skin comes in contact with a raw tomato, symptoms may include localized itching, irritation, stinging or a rash, in addition to one or more symptoms of oral allergy syndrome.