What is a food allergy rash, and what causes it? How do you know if your child has a food allergy rash? How to manage a food allergy rash, and how long does it usually last? We’ll cover everything families need to know about food allergy rashes in this definitive guide.
In our parent's guide to food allergy rashes, we'll answer the following most asked questions:
- What is a food allergy rash, and what causes it?
- How do you know if your child has a food allergy rash?
- What are the symptoms of a mild, moderate or severe allergic reaction?
- Where can food allergy rashes appear?
- How to manage a food allergy rash, and how long does it usually last?
- How do you test for a food allergy?
- How do you introduce allergens safely?
We’ll cover everything families need to know about food allergy rashes in this definitive guide.
What is a Food Allergy?
Normally, our immune systems protect our bodies from viruses, bacteria, and other foreign invaders that could harm us.
But when someone has a food allergy, their immune system mistakenly treats the proteins in a certain food (or foods) like these foreign invaders, and over-defends the body against these proteins. Their immune system makes special antibodies --- specific IgE antibodies --- that detect the food proteins and help fight them off.
These IgE antibodies trigger symptoms of an allergic reaction whenever the person eats a food they are allergic to. For example, if someone is allergic to peanut, they have IgE antibodies that detect and fight off peanut proteins, and that trigger allergic reaction symptoms (including a possible food allergy rash) whenever they eat peanuts.
Types of Food Allergic Reactions - Mild, Moderate, and Severe
Food allergy reactions can range from mild to severe, and can sometimes be life-threatening. Keep in mind, though, that a mild reaction can sometimes become severe. Also, symptoms of a food allergy reaction can vary from reaction to reaction. So, it’s impossible to predict what symptoms your child will develop each time they have an allergic reaction to food.
Symptoms of a food allergy reaction usually occur seconds to minutes after someone eats a food they’re allergic to, and almost always occur within a few hours of eating the food.
Symptoms of a mild or moderate allergic reaction may include:
- A food allergy rash concentrated in one area of the body (red, raised bumps)
- Redness in an area of the skin
- Swelling of the face, eyes or lips
- Itchy, watery eyes
- Some stomach pain
- Some nausea
- Mild coughing
- Worsening eczema
Symptoms of a severe food allergy reaction may include:
- A food allergy rash that spreads to many areas the body
- Swelling of the tongue
- Swelling or tightness of the throat
- Repeated, significant coughing
- Wheezing/noisy breathing
- Difficulty breathing /shortness of breath
- Change in voice or cry
- Struggling to vocalize
- Difficulty swallowing
- Repeated vomiting
- Pale appearance
- Drop in blood pressure
- Rapid heartbeat
- Loss of consciousness
- Feeling floppy (infants/young children only)
Signs Of Anaphylaxis
When the symptoms of a food allergy reaction are severe and involve more than one organ system, the reaction is classified as anaphylaxis. Anaphylaxis can be life-threatening. Call 911, and give epinephrine (use an Epi-Pen) immediately, if your child shows signs of anaphylaxis.
The National Institute of Allergy and Infectious Diseases (NIAID) provides more information on food allergy symptoms and management:
All About Food Allergy Rashes
A food allergy rash is the most common symptom of a food allergic reaction, especially in babies and children. It is also often the first symptom to appear (but not always). It could appear anywhere on the skin.
What does a food allergy rash look like?
A food allergy rash is raised, very itchy, and usually red or pink. It creates red, raised bumps on the skin. These bumps are usually rounded, and often have red flares around them. They are usually called hives, but are sometimes called wheals, urticaria or nettle rash.
In people with darker skin, a food allergy rash will also appear as raised, itchy bumps. But often, the bumps do not appear red at all, and instead have the same color as the person’s skin is normally. You also probably won’t see red flares around the bumps. (In some cases, a food allergy rash may still have a subtle red hue, or a darker red hue, when it appears on a person with brown or Black skin.)
Why do food allergies cause a rash?
When someone eats a food they’re allergic to, their IgE antibodies detect the proteins from that food. The IgE antibodies prime tissue cells (called mast cells) and blood cells to release a chemical called histamine, and other chemicals, as a way to defend against those proteins.
When the histamine and other chemicals get released, this causes blood vessels to widen (dilate) and become leaky. Fluids get released under the skin as a result, leading to inflammation under the skin. This leads to the raised food allergy rash on the skin.
Where can food allergy rashes appear?
Food allergy rashes can be concentrated in one or two areas of the body, or can spread throughout the body.
Places that food allergy rashes often appear include the face, arms, hands, legs, feet, stomach area, and back. But they could appear anywhere on the skin.
Each individual bump (wheal) from the rash can be as small as a few millimeters or as large as several inches across.
But a rash area may be much larger, because food allergy rash usually appears as batches or clusters of bumps. And someone could develop multiple rash areas at a time.
If a food allergy rash is concentrated in one area, the food allergy reaction is mild. But if the rash spreads to many areas of the body, this is a sign of a severe allergic reaction.
How long does a food allergy rash last?
Like other food allergy symptoms, a food allergy rash can appear seconds to hours after someone eats a food they're allergic to.
A food allergy rash usually lasts for several hours after food allergy reaction symptoms first appear. Sometimes, it can last for up to 24-48 hours.
Do all food allergy reactions produce a raised rash?
Even though food allergy rashes are a common allergy symptom, they may not appear during every food allergy reaction. Sometimes, a food allergy can turn areas of the skin red and/or itchy, but won’t produce the raised food allergy rash (hives).
Also, a food allergy rash is different from the rash that eczema causes. But food allergies can make eczema rashes worse (cause eczema to flare up). Learn the differences between a food allergy rash and an eczema flare-up here.
How to Manage a Food Allergy Rash
If your child develops any food allergy rash (or any other food allergy symptoms), immediately stop feeding them the food that you believe was the cause of the reaction.
The other steps in managing a food allergy rash vary depending on how severe the allergic reaction is.
Managing a Mild Food Allergy Rash
How to manage mild food allergy rashes, concentrated in small clusters on one area of the body?
If a doctor has explicitly recommended a dosage of antihistamine, you can give your child the antihistamine (such as Benadryl or Zyrtec) to treat mild hives. Antihistamine helps stop the release of the histamine that triggered the rash, in the case of a mild or moderate allergic reaction.
If your doctor hasn’t recommended a dosage of antihistamine, call your pediatrician or allergist to alert them about the hives, and ask about next steps.
Either way, continue to monitor your child in case their mild allergic reaction turns severe.
Hydrocortisone cream may also help to relieve the itchiness of the rash, although it won’t make the rash go away.
Managing a Severe Food Allergy Rash
If your child develops a significant food allergy rash all over their body, but no other symptoms of a food allergy reaction, call your doctor immediately.
Continue to monitor your child for other symptoms of a food allergy reaction, because if other severe symptoms emerge, your child will have anaphylaxis. If you have epinephrine (an Epi-Pen), give your child an injection. An antihistamine will not be able to stop this severe, widespread rash.
If your child develops a food allergy rash all over their body, and it’s accompanied by severe symptoms in at least one other organ system, your child is experiencing life-threatening anaphylaxis and needs emergency assistance.
Inject epinephrine (an Epi-Pen) immediately, and call 911. Epinephrine is the only medicine that can stop anaphylaxis --- antihistamines cannot stop this severe reaction.
A Note About Food Allergic Reactions and Children
Many people wonder about the differences between food allergy reactions in children vs. adults.
Food allergy rash is one of the most common food allergy symptoms in children and adults. The way it appears in every age group is also largely the same. In fact, food allergies generally cause the same set of symptoms in children as they do in adults.
But even though food allergies cause similar symptoms across all age groups, the most common types of food allergies are different in children vs. adults.
In young children (5 years of age and younger), cow’s milk, egg, and peanut allergies are the most common food allergies. According to one study by Dr. Ruchi Gupta, these three foods are responsible for around 80% of food allergies in young children.
In addition to milk, egg, and peanut allergies, tree nut allergies are also very common in children age 14 and under.
Out of these four food types, peanut and tree nut allergies are most responsible for severe reactions in children, but any food has the potential to cause a severe reaction.
In contrast, the most common food allergy in adults is shellfish allergy, which is largely an adult allergy. Finned fish allergies are another common adult allergy --- and finned fish allergies also tend to develop in adulthood.
Check out our previous article for more on food allergies in children vs. adults.
Food Allergy Testing
If your child develops a rash after they eat a certain food, and it looks similar to the food allergy rash we’ve described above, remember that food allergy testing is the only way to determine whether your child truly has a food allergy. So, it’s best to make an appointment with an allergist for testing.
Food allergies can be diagnosed through three types of tests: a skin prick test, a blood test, and an oral food challenge.
A skin prick test: An allergist pricks your child’s forearm with a needle containing food protein from the suspected problem food. Then, they monitor your child to see if an allergic reaction develops around the area where their skin was pricked.
A blood test: An allergist checks your child’s blood for IgE antibodies that respond to certain food proteins.
An oral food challenge: Your child eats small amounts of the suspected problem food under an allergist’s supervision, to see if they develop an allergic reaction. This is the most accurate way to diagnose a food allergy.
Introducing Allergens Safely
New clinical guidelines recommend introducing babies to common allergy-causing foods during their first year of life, as a way to help them safely enjoy these foods in the future.
As the U.S. Department of Agriculture (USDA) recommends in their new dietary guidelines, “Potentially allergenic foods (e.g., peanuts, egg, cow milk products, tree nuts, wheat... and soy) should be introduced when other complementary foods are introduced to an infant’s diet.”
Ready. Set. Food! can help you easily and safely introduce these common allergy-causing foods to baby, following the new clinical guidelines. And since the first two stages of our system fully dissolve into a bottle of breastmilk or formula, you can start introducing your baby to peanut, egg, and milk as early as 4 months of age, even before they’re ready for solids.
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