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Symptoms of a food allergy include a raised, itchy red rash, swelling of the face, eyes, lips and tongue, and shortness of breath.
- Food allergyThe symptoms of a food allergy almost always develop a few seconds or minutes after eating the food.
Some people may develop a severe allergic reaction (anaphylaxis), which can be life threatening.
The most common type of allergic reaction to food is known as an IgE-mediated food allergy.
tingling or itching in the mouth
a raised, itchy red rash (hives) – in some cases, the skin can turn red and itchy, but without a raised rash
swelling of the face, mouth (angioedema), throat or other areas of the body
wheezing or shortness of breath
feeling dizzy and lightheaded
feeling sick (nausea) or vomiting
abdominal pain or diarrhoea
hay fever-like symptoms, such as sneezing or itchy eyes (allergic conjunctivitis)
The symptoms of a severe allergic reaction (anaphylaxis) can be sudden and get worse very quickly.
Initial symptoms of anaphylaxis are often the same as those listed above and can lead to:
trouble swallowing or speaking
feeling dizzy or faint
Anaphylaxis is a medical emergency. Without quick treatment, it can be life threatening. If you think you or someone you know is experiencing anaphylaxis, dial 999 and ask for an ambulance as soon as possible.
Non-IgE-mediated food allergy
Another type of allergic reaction is a non-IgE-mediated food allergy. The symptoms of this type of allergy can take much longer to develop – sometimes up to several days.
Some symptoms of a non IgE-mediated food allergy may be what you would expect to see in an allergic reaction, such as:
redness and itchiness of the skin – although not a raised, itchy red rash (hives)
the skin becomes itchy, red, dry and cracked (atopic eczema)
Other symptoms can be much less obvious and are sometimes thought of as being caused by something other than an allergy. They include:
vomiting with or without diarrhoea
abdominal cramps constipation
in babies: excessive and inconsolable crying, even though the baby is well fed and doesn't need a nappy change (colic).
Some children can have a mixed reaction where they experience both IgE symptoms, such as swelling, and non-IgE symptoms, such as constipation.
This can happen to children who have a milk allergy.
Exercise-induced food allergy
In some cases, a food allergy can be triggered after eating a certain food and then exercising. This can lead to anaphylaxis in severe cases, sometimes known as food-dependent exercise-induced anaphylaxis.
Drinking alcohol or taking an non-steroidal anti-inflammatory drug (NSAID) such as aspirin or ibuprofen may also trigger an allergy in people with this syndrome.
Page last reviewed: 15 April 2019
Next review due: 15 April 2022
We’ve answered some of your most frequent questions about managing food allergies.
We’ve answered some of your most frequent questions about managing food allergies.
What is a food allergy?
A food allergy is when your body’s immune system reacts to a food protein because it has mistaken that food protein as a threat. Symptoms can range from mild to life-threatening.
What is the difference between food allergy and food intolerance?
Food allergy is sometimes confused with food intolerance. Food allergies involve your immune system and can be life-threatening. An intolerance is when your body has trouble digesting a food. It can make you feel bad, usually with an upset stomach, but it is not life-threatening. The most common intolerance is to lactose—which is a natural sugar found in milk.
What are the most common food allergens?
More than 170 foods are known to cause food allergies, but eight foods account for 9 out of 10 reactions in the United States. They are milk, eggs, peanuts, tree nuts, soy, wheat, fish and shellfish.
What are the symptoms of a food allergy reaction?
An allergic reaction to food can have many different symptoms, and a single person can experience different symptoms from one reaction to the next. Many reactions start with skin symptoms, like hives or a rash, but some do not. More serious symptoms like a drop in blood pressure and trouble breathing can be life-threatening. Talk to your allergist and work with them to fill out a Food Allergy & Anaphylaxis Emergency Care Plan to be prepared in an emergency. A complete list of symptoms of a food allergy reaction is available here.
What is anaphylaxis?
Anaphylaxis is a serious allergic reaction that comes on quickly and may cause death. Early use of an epinephrine auto-injector is the primary treatment for anaphylaxis. A complete list of the symptoms of anaphylaxis and more information are available here.
Will antihistamines stop anaphylaxis?
No. While antihistamines can help relieve some mild symptoms from an allergic reaction, such as an itchy mouth or hives, they cannot stop the life-threatening symptoms of anaphylaxis.
How much of a food allergen does it take to cause a reaction?
Even trace amounts of a food allergen can cause a reaction in some people with food allergies. Although ingestion is the primary cause of severe reactions, in some cases, skin contact or breathing in a food protein (e.g., steam from cooking shellfish) can cause symptoms.
How long does it take for a reaction to start after eating a food?
Symptoms usually start as soon as a few minutes after eating a food and as long as two hours after. In some cases, after the first symptoms go away, a second wave of symptoms comes back one to four hours later (or sometimes even longer). This second wave is called a biphasic reaction. The risk of a biphasic reaction is why patients who have a severe reaction should stay at a hospital for four to six hours for observation.
Who is most at risk for a severe allergic reaction to food?
Anyone who has a food allergy can have a severe allergic reaction to food. However, having asthma puts you at higher risk. Fatal outcomes of anaphylaxis include a disproportionate number of teens and young adults, possibly because they take more risks with their food allergies (eating dangerously and delaying treatment).
Can the severity of a person’s allergic reactions to food be predicted from his or her previous reactions?
No. Someone whose reactions have been mild in the past may suddenly experience severe reactions that could be deadly.
How many people have food allergies?
As many as 32 million Americans have food allergies, including nearly 6 million children.
Why are food allergies increasing?
The Centers for Disease Control and Prevention have reported a 50 percent increase in the number of children with food allergies since the late 1990s. Many theories have been suggested as to why the number of people with food allergies is growing, but scientific research has not yet found the cause.
Is there a cure for food allergy?
Not yet. Strict avoidance of the food allergen is the only way to prevent a reaction and an epinephrine auto-injector is the only medicine to stop a severe reaction called anaphylaxis.
Can a person outgrow their food allergies?
Peanut, tree nut, fish and shellfish allergies usually are lifelong. Milk, egg, wheat and soy allergies usually begin in childhood and eventually may be outgrown.
If I think I or my child has outgrown an allergy to a food, is it okay to try a small amount of that food?
No. Only your allergist can test for this. For more information on tests for food allergies, click here.
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Emergency Care Plan English
EDUCATION Anaphylaxis EDUCATION
Newly Diagnosed Packet
EDUCATION SHARE Facebook Twitter Email LinkedIn Education Milk Egg Shellfish Fish Tree Nut Sesame Wheat Peanut Soy Newly Diagnosed
Children with Food Allergies
College Staff Educators
Learn more about food allergy including symptoms of food allergies and causes of food allergies, as well as when to seek care.
Food Allergy Is this your child's symptom?
Allergic reactions to foods
The most common symptom is hives
Questions about food allergies
Oral Allergy Syndrome is also covered. The main symptom is mouth itching and swelling. The main triggers are raw fruits and veggies.
Symptoms of Food Allergies
Hives all over and swelling of the face are the most common symptoms. Hives are raised pink bumps with pale centers (welts). They look like bug bites.
Mouth itching and swelling
Runny nose and coughing
Vomiting and diarrhea
Life-threatening allergic reactions also must have trouble breathing and/or swallowing. The medical name for this is anaphylaxis. Most of these reactions have a sudden onset within 10 to 20 minutes. All occur within 2 hours of eating a certain food. People who have had this carry an emergency kit like an Epi-Pen.
Causes of Food Allergies
8 foods cause 90% of food allergies
In the first year of life: cow's milk, soy milk and egg
Older children: peanuts, tree nuts, fish, shellfish and wheat
Shellfish include shrimp, crab, lobster, clams, oysters and scallops
Tree nuts include all the nuts (such as almonds and cashews) except peanuts.
Of children with a proven food allergy, 40% have severe reactions. The other 60% have mild reactions.
Peanuts and tree nuts are the most common triggers for severe reactions.
Cross Reactions with Other Foods
Children with allergies listed below can react to other foods:
Cow's milk allergy: 90% also react with goat's milk and 40% with soy milk
Egg: 5% react with chicken
Peanut: 5% react with other legumes (like peas or beans). About 30% also react to tree nuts.
Tree nut: 40% react with other tree nuts
Fish: 50% react with other fish. Only 10% also react to shellfish.
Shellfish: 70% react with other shellfish
Melon: 90% react with banana and avocado
How Long do Food Allergies Last?
Cow's milk: 80% outgrown by age 16
Soy milk: 80% by age 16
Egg: 70% by age 16
Peanut: 20% by age 16
Tree nut: 10% by age 16
Allergic Disease - Can You Prevent with Diet?
Most allergic diseases (food allergies, eczema and asthma) cannot be prevented.
Helpful: Feeding only breastmilk for 6 months or longer
Not helpful: Avoiding high-risk foods for pregnant or breastfeeding women
Not helpful: Soy formulas instead of cow's milk formula
Not helpful: A delay in starting baby foods past 6 months
Not helpful: A delay in starting high-risk foods like peanut butter or eggs
Oral Allergy Syndrome (OAS)
A minor reaction to some raw fruits and veggies
Causes itching and swelling only to the lips and tongue
Also called Pollen-Food Syndrome
Symptoms of OAS
Rapid onset of itching (or tingling) and swelling of the mouth.
This can involve the lips, tongue, throat, and roof of the mouth.
The uvula (tag of tissue hanging down in back) can become very swollen.
These symptoms follow eating a high-risk raw fruit or veggie.
OAS can start by age 5.
Serious symptoms or very bad reactions rarely happen.
Causes of OAS
A contact allergy. It only involves the parts of the mouth that touch the raw food.
Trigger foods for OAS are always raw (not cooked.)Fresh Fruits. These include apple, apricot, banana, cherry, melons, orange, peach and pear.Raw Veggies. These include carrot, celery, parsley, potato and tomato. Carrots and celery have the highest risk for also causing serious symptoms.Certain Seeds. These include sunflower seeds and fennel seeds.
OAS and Nose Allergies Can Be Linked
Over 50% of people who are allergic to pollen also have OAS. This means 10% of all people.
Ragweed pollen allergy can cross-react with all melons. Also, sometimes with bananas and tomatoes.
Birch pollen allergy can cross-react with raw potatoes, carrots, celery and apples.
Grass pollen allergy can cross-react with tomato and kiwi.
When to Call for Food Allergy
Call 911 Now
Life-threatening allergic reaction to similar food in the past. Food eaten less than 2 hours ago.
Trouble breathing or wheezing
Hoarse voice or cough start all of a sudden
Trouble swallowing, drooling or slurred speech start all of a sudden
You think your child has a life-threatening emergency
Call Doctor or Seek Care Now
Hives all over start 2 to 4 hours after eating high-risk food. High-risk foods include nuts, fish, shellfish, or eggs.
Major face swelling (not just lips) starts 2 to 4 hours after eating high-risk food
Vomiting or stomach cramps starts 2 to 4 hours after eating high-risk food
Your child looks or acts very sick
You think your child needs to be seen, and the problem is urgent
Contact Doctor Within 24 Hours
Other symptoms that might be from a food allergy and present now
You think your child needs to be seen, but the problem is not urgent
Contact Doctor During Office Hours
Recurrent symptoms that might be from a food allergy but not present now
Oral Allergy Syndrome suspected but never confirmed by a doctor
Food allergy diagnosed and you want to restart that food
You have other questions or concerns