A food allergy is present when the immune system has an abnormal reaction to proteins in a particular food. Food-allergy symptoms, which can be triggered by ingesting even minute amounts of the food, usually happen within minutes but may, occasionally, happen a few hours later. Food allergies can begin in childhood or in adulthood, with some people suddenly having allergic responses to foods that have never caused problems. In other cases, allergies appear after a food is consumed for the first time. Certain food allergies that affect young children may eventually go away.
Some of the most common foods that cause allergic reactions are:
- Cow's milk
- Eggs
- Peanuts
- Tree nuts
- Fish
- Shellfish
- Wheat
- Soy
Symptoms of Food Allergies
Food allergies produce a wide range of symptoms. They may be relatively mild, causing only discomfort, or severe enough to be fatal. Any time an allergic reaction occurs, an appointment should be made with an allergist in order to determine the allergy's source.
Symptoms of a food allergy may include:
- Itchy and/or flushed skin
- Hives
- Vomiting, abdominal pain and diarrhea
- Sneezing, runny nose and congestion
- Itchy or watery eyes
- Swelling under the skin (angioedema)
In more severe cases, symptoms may include:
- Swelling of the throat, and hoarseness
- Difficulty breathing, and wheezing and chest tightness
- Dizziness or loss of consciousness
- Anaphylactic shock
If an anaphylactic reaction occurs, emergency medical care should be sought immediately. Delaying treatment can result in coma or, even, death.
Causes of Food Allergies
A food allergy is caused by the immune system's incorrectly identifying a particular food as a potentially dangerous foreign substance. This initiates a reaction in which antibodies are produced to combat the allergen. Afterwards, whenever that particular food is eaten, the antibodies respond by triggering the release of histamines and other chemicals throughout the immune system. It is these chemicals that are responsible for the various symptoms food allergies produce.
Risk Factors Associated with Food Allergies
Certain people, with children being particularly susceptible, are more likely than others to develop food allergies.The risk for acquiring a food allergy may be higher in people with:
- Other allergy-related conditions (eczema or asthma, for example)
- A history of food allergies, even if symptoms have disappeared
- A family history of food allergies or other types of allergic reactions
Diagnosis of Food Allergies
Many people who experience reactions to foods have an intolerance to them rather than a true allergy. For example, lactose intolerance from milk is easily confused with a milk allergy. Food intolerance frequently has symptoms similar to those of a food allergy, especially if there is gastrointestinal distress involved. However, people with food intolerance can often safely eat a small quantity of the problematic food without having a reaction. In contrast, a person with a true food allergy typically cannot consume any amount of the trigger food without developing symptoms.
Therefore, accurate diagnosis of true food allergies is important to prevent future allergic reactions. An allergist will be able to diagnose a food allergy by taking a patient's complete history, and performing skin testing and blood testing. Occasionally, an allergist-supervised "food challenge" may be required to confirm the diagnosis.
Treatment of Food Allergies
The most effective treatment for a food allergy is strict avoidance of the problematic food. Checking ingredient labels is a must, as is asking about ingredients in food prepared in restaurants and at the homes of others.
For someone who has only mild allergic reactions, an antihistamine may be an effective treatment for relieving symptoms. For someone who experiences severe reactions, immediate medical attention is required, as is having an allergist prescribe injectable epinephrine that can be carried at all times.
