Cause

• The cause of a tomato allergy is in a certain protein found in the tomato plant. Some individual's immune systems recognize the protein as a potentially harmful substance. The body begins to produce antibodies and release histamine throughout the body in order to ward off the protein. Histamine causes the body to react with watery eyes, itchy throat, congestion and swelling in various parts of the body.
  
  

Symptoms

• The most common symptoms of an allergic reaction to tomatoes are: lip and tongue tingling, runny nose, watery eyes, sore eyes, asthma, lip swelling, tongue swelling and nausea. There are many other symptoms that are much less common like facial swelling, persistent cough and vomiting.
  
  

Treatment

• If the reaction is topical (on the skin), wash the exposed area with soap and water immediately. Apply a topical antihistamine cream to the localized area and the reaction should clear up within 15 minutes. If the tomatoes were ingested, take an over-the-counter antihistamine to alleviate the symptoms. The most common antihistamine for treating a tomato allergy is diphenhydramine or Benadryl. This medication should begin fighting off the histamine in your body within 10 to 15 minutes.
  
  

Prevention

• In order to prevent an allergic reaction to tomatoes, a person should have allergy blood work done. Blood tests can either confirm or dispel the possibility of a person having a tomato allergy. If a person is allergic to tomatoes, he or she may also be allergic to potatoes because they contain a similar protein. Once an allergy has been confirmed, a person should avoid these foods all together.
  
  

Complications

• Anaphylactic shock is the most common complication with a tomato allergy. Anaphylactic shock is when a person's body has a serve reaction to tomatoes that sends his or her body into a form of shock and begins to shut down. Someone experiencing anaphylactic will become short of breath, pass out and can have a seizure. If anaphylactic shock is a person's reaction, he or she needs medical attention immediately and should call 911.