The immune system is designed to defend against pathogens — foreign invaders like bacteria and viruses. But sometimes, it can get confused and launch an attack in response to certain foods, causing an allergic reaction. This is what happens to the more than 20 million people in the United States with food allergies.

Most food allergy symptoms happen within two hours of exposure to a food allergen — often, within minutes. Some people feel sick to their stomach, get dizzy, start coughing or sneezing, or feel faint. Others develop itchy rashes, which may appear around their mouth or all over their body.

In this article, we’ll take a closer look at what these food allergy rashes might look and feel like, as well as when to seek medical treatment for yourself or your child.

Oral Allergy Syndrome

Oral allergy syndrome (OAS) is a mild allergic reaction to certain raw fruits, vegetables, and seeds. When someone with OAS comes into contact with an allergen, their mouth and lips may itch or swell. OAS can also cause itchy ears and mouth hives. Fortunately, this type of reaction is rarely serious and doesn’t typically affect children younger than 5.

Treatment for OAS

OAS symptoms usually remain limited to the mouth area and generally don’t spread to other parts of the body. In most cases, treatment usually isn’t necessary, since the symptoms often go away once the food is swallowed or removed from the mouth. Cooking the offending food or avoiding it altogether can help prevent a reaction in the future.

Although food allergies often cause itchy skin, they aren’t the only reason people get rashes. You or your child may get rashes from poison ivy, medication side effects, weather changes, eczema, or another type of reaction.

If you’re not sure what caused the reaction, your dermatologist or allergist may recommend a skin prick test or an oral food challenge to learn more about your condition.

Itchy Rash and Hives

Hives are one of the most common symptoms of a food allergy. They look like raised bumps with pale centers, similar to bugbites. Hives and rashes can vary in color based on your skin tone. If you have a darker skin tone, your hives might appear slightly lighter or darker than your natural skin tone or similar to the color of your skin. If you have a medium or light skin tone, your hives might appear red or pink.

Several members of MyFoodAllergyTeam have shared experiences with itchy skin rashes. In some cases, they can pinpoint the cause, while other times it’s harder to tell.

Hives look like raised bumps with pale centers, similar to bugbites. They can vary in color based on your skin tone.

“The baby broke out in another rash today with a few hives,” one member wrote. “I got the rash pretty cleared, but she’s still super itchy. Not sure what exactly broke her out, but definitely going to single it out.”

Others have said:

• “I get a rash when I consume coconut oil. I itch and itch and get a rash all over my body.”
• “I had coffee a few days ago and broke out in a rash.”
• “I think my freshly picked tomatoes have given me an itchy rash!”

Hives from food allergies are usually short-lived and, in most cases, go away within six hours. Some people break out in hives frequently without being allergic to anything. These are called idiopathic or spontaneous hives.

Treatment for Hives

If the child or adult with hives is stable, medical treatment may not always be necessary. However, it’s always a good idea to contact your doctor if you have concerns or if this is the first time you or your child is experiencing hives.

Taking a cool bath for 10 minutes can help relieve itching. In addition, over-the-counter antihistamines like diphenhydramine (Benadryl) or cetirizine (Zyrtec) may also be recommended. Ask your doctor or your child’s pediatrician if they have a preference. Some pediatricians favor cetirizine over diphenhydramine because it has fewer side effects.

Rash With a Skin Infection

“I’ve been itching a lot. I’m not certain why, but it may be dry skin. The doctor gave me a cream to use. We will see if it works,” said a member of MyFoodAllergyTeam. Others have mentioned that they get itchy when they eat something that “doesn’t agree with them” or that their “body didn’t like.”

When a rash becomes infected by pathogens on the skin or in your fingernails, it may feel hot to the touch, ooze pus, or start crusting over.

It’s common for rashes to appear as a result of scratching. Getting the itch under control can help prevent rashes and further problems like skin infections.

“I had a rash recently and chalked it up to allergies. It was partially an allergy, and the rest was due to an overgrowth of staph. Yikes!” one member shared. “Took a long road to recovery. I’m finally on the other side. Which came first, the allergy or the staph? I think the allergy made me scratch.”

When a rash becomes infected by pathogens on the skin or in your fingernails, it may feel hot to the touch, ooze pus, or start crusting over. The area can also become swollen and inflamed, and the skin may look tight or shiny. Impetigo (a type of strep infection of the skin) can cause blisters to form, which eventually break open and leave temporary marks and a dark yellow crust on the skin. In some cases, infections are serious and require hospitalization.

Treatment for Infected Rashes

If you think you or your child may have an infected rash, it’s important to see a health care provider as soon as possible. Skin infections, if left untreated, can spread to other people and even become life-threatening in some cases. A doctor will usually diagnose the specific bacteria, virus, or fungus responsible for the infection by taking a skin sample and sending it to the lab. Once the cause is identified, your provider will recommend the best treatment, which may include a medicated ointment or cream, or an antibiotic to help clear up the infection. Your or your child’s health care provider can also provide instructions on how to properly clean and care for the infection as it heals.

Other Allergic Rashes

Although food allergies often cause itchy skin, they aren’t the only reason people get rashes. You or your child may get rashes from poison ivy, medication side effects, weather changes, eczema, or another type of reaction.

Contact dermatitis can cause a swollen, scaly, itchy rash, often in response to harsh cleaning products or industrial chemicals. In allergic contact dermatitis, exposure to poison ivy, latex, nickel, or other substances leads to itchy skin, which sometimes comes with blisters, bumps, and swelling.

Several medications also list skin rashes as a possible side effect. Antibiotics, diuretics (water pills), or other drugs may also produce discolored skin spots or bumps. Drug rashes may appear pink or purple, depending on your skin tone.

When To Call the Doctor

Speak with your health care provider or your child’s pediatrician if the rash is new, severe, or doesn’t respond well to over-the-counter treatments. To help the doctor make the right diagnosis, you can write down the timeline of symptoms and take photos of the rash. Your doctor may prescribe medications for food allergies, or recommend other over-the-counter options to help manage symptoms.

Always seek emergency medical treatment if you or your child are having trouble breathing. This can be a sign of anaphylaxis, which is a life-threatening allergic reaction. Your doctor might prescribe an epinephrine auto-injector to carry with you in case of anaphylaxis.

Talk With Others Who Understand

MyFoodAllergyTeam is the social network for people with food allergies and their loved ones. Here, more than 42,000 members from around the world come together to ask questions, offer support and advice, and connect with others who understand life with food allergies.

What symptoms of food allergies are most common for you or your child? Have you ever experienced a severe allergic reaction that included a skin rash? Share in the comments below, or start a conversation by posting on your Activities page.