Foods That Cause Itching: Common Food Allergies & Symptoms - Verywell Health

Food allergies occur when your body's immune system mistakenly reacts to a specific food as a dangerous foreign substance. Food allergies are common, affecting 32 million Americans.

A typical allergic reaction to food and other substances is itching. That's because when the immune system responds to an allergen, it releases a chemical called histamine, which frequently causes itching. Sometimes, just touching particular foods can lead to itching. 

This article explains common food allergies that cause itching, how to tell if you have a food allergy, and how to treat it. 

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Common Food Allergies That Cause Itching

Some foods are more prone to cause an allergic reaction than others. The Food Allergen Labeling and Consumer Protection Act of 2004 (FALCPA) identifies eight foods as major food allergens, which account for 90% of food allergies.

In the U.S., a food that contains any of the top eight food allergen ingredients must be clearly labeled with the allergen source.

Soy

Soybeans are a member of the legume family. You'll find soy in food items like soymilk, tofu, edamame, and miso. 

Soy allergies typically appear in infancy and childhood. Many people outgrow a soy allergy, but some people will be affected their whole lives.

A soy allergy can cause various reactions, including hives (urticaria), a skin rash characterized by lots of small, raised, red bumps. This type of rash is extremely itchy.

Tree Nuts

Tree nuts are one of the food allergies most commonly linked to anaphylaxis, a potentially deadly allergic reaction. Often, people confuse peanuts with tree nuts, but peanuts are actually in the legume family.

Tree nuts include:

• Almonds
• Brazil nuts
• Cashews
• Macadamia nuts
• Pecans
• Pine nuts
• Pistachios
• Walnuts

If you have tree nut allergies, you need to avoid whole nuts. In addition, you should look carefully for nuts as an ingredient in processed or prepared foods, and butter and oils. 

Itching in the mouth, throat, skin, and eyes is common with tree nut allergies.

Peanuts

Peanut allergies are so common in children that many classrooms have gone "nut-free" to avoid potentially exposing an allergic child to the allergen. Peanut allergies can be life-threatening, so avoiding peanuts is critical if you are allergic.

Research has found that peanut allergens can remain present on table surfaces for 110 days.

Children with severe eczema or egg allergies are at increased risk of developing peanut allergies.

Peanut allergies have a range of symptoms, including hives. Due to the potential for severe allergic reactions, your healthcare provider may prescribe epinephrine if you have a peanut allergy. Epinephrine is a synthetic form of adrenaline (a stress hormone), which you take via an EpiPen injection to stop a severe allergic reaction. 

Shellfish

Shellfish include crustaceans like crab, lobster, and shrimp. They also include mollusks like clams, mussels, oysters, and scallops. Unfortunately, shellfish allergies also tend to be severe and can result in life-threatening reactions. 

About 2% of Americans have a shellfish allergy. This allergy tends to first occur in adulthood, and it tends to be lifelong when it happens.

Skin reactions to shellfish can include hives. People with shellfish allergies need to be careful about cross-contamination, especially when eating out. Be sure to tell your server if you have a shellfish allergy (or any other food allergy) so that the kitchen can take precautions. 

Wheat

Wheat allergies are sometimes confused with celiac disease, which is an autoimmune disease that affects the small intestine. In a wheat allergy, a person is allergic to the protein found in wheat.

Because wheat is such a common ingredient in prepared and processed foods, be sure to read labels carefully. Foods with wheat include:

• Baked goods
• Bread
• Pasta
• Processed foods

People with asthma or eczema are more prone to developing an allergy to wheat. As with other food allergies, hives are a common symptom. 

Cow's Milk

A milk allergy is not the same thing as lactose intolerance. A milk allergy is when you are allergic to the protein in milk, whereas lactose intolerance is the inability to process the sugar lactose.

Milk is one of the most common food allergies in children, affecting between 0.5% and 3% of children in developed countries by age 1.

Milk is in dairy products, including:

• Butter
• Cheese
• Cow's milk
• Ice cream
• Yogurt

Like wheat, cow's milk is in many prepared and processed foods, so read product labels carefully.

Eggs

The protein in eggs triggers egg allergies. People can be only allergic to specific parts of the egg, like the egg white or the yolk. However, if you have an egg allergy, it's best to avoid eggs entirely.

Egg allergies that develop in childhood sometimes resolve by adulthood. If you have an egg allergy, watch out for eggs in baked goods and processed foods. 

Like other food allergies, eggs may result in hives, among other allergic reactions. Egg allergies may also be severe.

Eggs and Vaccines

Certain vaccines may pose a risk if you have an egg allergy because they contain small amounts of egg protein. Therefore, talk to a healthcare provider about your allergy before receiving vaccines, as some of them have egg-free alternatives for people with allergies. 

Finned Fish

A finned fish allergy is not the same as a shellfish allergy. Therefore, it is possible to have one and not the other.

Finned fish include:

• Cod
• Eel
• Halibut
• Pollock
• Salmon
• Snapper
• Tuna

In addition to avoiding fish, you should also be careful about food items derived from fish. These include things like caviar, omega-3 supplements, and gelatin.

Common Food Skin Irritations

Some foods are more likely to result in contact dermatitis (skin itching and rash).

Tomatoes 

Tomato allergies commonly cause itching and hives. Sometimes, though, a strange phenomenon known as oral allergy syndrome (OAS) may be responsible for your itchy mouth and skin after you eat a tomato.

What Is Oral Allergy Syndrome?

OAS is cross-reacting allergens found in pollen and some food plants.

In the case of tomatoes, your immune system may identify interacting grass pollen in similar tomato proteins and react to it. 

Citrus Fruits

Citrus allergies commonly result in the skin, mouth, tongue, and lips itching. Citrus, like tomatoes, is associated with OAS and grass pollen, in particular. They can also cause contact-based skin reactions in some people. 

Foods With Nickel

While jewelry most commonly comes to mind when you think of nickel, you can also find it in some foods. Foods that are higher in nickel include:

• Beans
• Canned foods
• Chocolate
• Grains
• Lentils
• Nuts
• Oatmeal
• Peas
• Shellfish
• Soybeans
• Whole wheat bread

A skin rash on the hands has been associated with dietary nickel allergies.

Spices

Allergies to spices can result in itching and skin rashes. Some can cause a rash when they make contact with the skin. They can also result in mouth itching, primarily due to OAS. 

Do I Have a Food Allergy?

You ingest many food combinations, so pinpointing which ingredient or food item is causing your symptoms can be tricky. It often takes a bit of detective work.

Your healthcare provider may ask you to keep a food diary. This process involves tracking everything you eat and noting any symptoms. Doing so can sometimes help you see a pattern of symptoms that correlate with certain foods.

In addition, an elimination diet, where you eliminate certain suspect foods to see if your symptoms improve, may also narrow down the culprits. 

Finally, your healthcare provider may suggest allergy testing to determine your allergy. These may include skin tests or blood tests. 

Food Allergy or Food Sensitivity?

Food sensitivities are not the same as food allergies. Food sensitivities (also called intolerances) are reactions to food that do not involve the immune system. Typical examples are lactose intolerance or gluten sensitivity. Reactions to sensitivities tend to be milder and involve digestive upset. 

Treatment

As with all allergies, avoiding the allergen is the first line of treatment. Avoiding allergens is especially critical for food allergies since some can be severe. 

Food allergy treatment includes:

• Avoiding allergens
• Antihistamines
• Epinephrine for emergencies
• Corticosteroids
• Inhalers for those with asthma

Summary

Food allergies commonly cause itchy skin rashes. Treatment primarily consists in avoiding the foods to which you are allergic. However, if you accidentally contact a food allergen, antihistamines may help, especially with itching. If you have had a severe allergic reaction or a healthcare provider thinks you may be at risk of one, they will likely prescribe an EpiPen for use in an emergency.

A Word From Verywell

Since food allergies can be severe, it's essential to pay attention to any skin rash you think may be related to a food allergy. Keeping a food diary and noting any symptoms alongside the food you eat can be an excellent way to pinpoint which foods may be causing your trouble. A healthcare provider might also suggest skin prick tests or blood tests to definitively diagnose your allergies.

Frequently Asked Questions

• If you experience itching after eating, you are likely reacting to something you ate. Keeping a food diary may help you determine what is causing your itching.

• Since sugar naturally occurs in some foods and is added to many foods, it can be easy to overdo it. Too much sugar can trigger eczema flare-ups in some people. In addition, some people have a sugar allergy or intolerance, which can cause itching.