Oral allergies to tomatoes can be caused by cross-reactivity to Ryegrass and other grass pollens. This can also occur with potatoes, melon, and watermelon. For those with a food intolerance to tomatoes, symptoms of intolerance can be inconvenient and aggravating. However, for those who have a true oral allergy to tomatoes, ingesting them can have fatal results.
The tomato plant, eggplant, potatoes, and tobacco plant are all members of the Deadly Nightshade family. If a person is truly allergic to tomatoes, it is highly probable they will also be allergic to these other plants.
Allergy to tomatoes can cause hives and angioedema. Hives are dark red, itchy lumps that appear on the skin. Angioedema is the same type of reaction beneath the skin. Angioedema can constrict airways and blood vessels with fatal results without immediate injection of steroids to reduce the swelling. Other allergy symptoms to tomatoes include oral allergy syndrome, dermatitis, rhinitis, and abdominal pain.
Dermatitis, hives, angioedema, and allergic rhinitis can occur from skin contact with the tomato plant leaves, pollen from the plant, or contact with the skin or seeds of the fruit. Oral allergy syndrome, of course, occurs from eating the fruit of the plant, and is usually more severe when ingested fresh than when cooked.
Allergic rhinitis is caused by pollen from the tomato plant and results in the same hay fever symptoms of allergy to grass. Sneezing, itching nose, runny nose, and stuffy or blocked feeling of the nose occurs. Allergic rhinitis to tomato plants can also cause allergic conjunctivitis, a condition in which the eyes become watery and itch. Without proper and quick medical treatment, the conjunctivitis symptoms rapidly progress to include a painful feeling of grit or sand beneath the eyelid. This grit can scratch the surface of the eye and be felt in the corners of the eye, particularly on awakening. Medicated eye drops need to be administered immediately or the conjunctivitis can lead to a severe infection capable of swelling the eye closed and forming pus.
Contact dermatitis occurs through direct contact with the plant, either tending it in the garden or harvesting the fruit of the plant. Dermatitis from plants can cause a rash and severe itching. Immediate washing with soap and water of the area and application of a topical steroid cream or ointment will usually stop the symptoms.
Oral allergy syndrome symptoms include a tingling sensation in the lips, constriction of the chest, itching around the mouth, hives, skin rash, diarrhea, vomiting, abdominal pain, and difficulty breathing. Some people are able to eat cooked forms of tomatoes without symptoms even though they cannot eat tomatoes raw. In others the symptoms are so severe they cannot eat tomatoes in any form, raw or cooked.
Due to the severity of consequences with food allergies, anyone who experiences the above symptoms should contact their physician immediately.