When a child has a serious food allergy, any symptom — including a fever — can be alarming. While food allergies don’t cause fevers, certain medical conditions that come with fevers can cause symptoms that are similar to those of food allergies.

Children who are allergic to peanuts and other types of food may experience a wide range of symptoms. These can include skin reactions such as itching and hives, respiratory symptoms such as coughing and trouble breathing, gastrointestinal symptoms such as diarrhea and vomiting, or other symptoms like anxiety, heart palpitations, and changes in behavior.

Read on to learn five facts about fevers in children with food allergies, including what causes them and how to recognize when a fever might be an emergency.

The Basics: Fever, Allergy, and the Immune System

A fever, medically known as pyrexia, happens when the body’s temperature rises above its normal range of 97 to 99 degrees Fahrenheit by more than half a degree. A fever usually happens when the body’s immune system is fighting a foreign substance or infection. While there’s no single temperature that defines a fever, a temperature of 99.1 F or higher is generally considered a low-grade fever. A temperature of 102.4 F or higher is considered a high-grade fever and can be a sign of a serious condition. Be sure to contact your doctor if your child has a high-grade fever.

Food allergies happen when the immune system reacts to a food allergen — a particular protein in food. With allergies, the immune system will have an inflammatory response that causes a variety of symptoms. However, allergies do not trigger the release of the inflammatory proteins that cause a fever.

If your child has a fever along with food allergies, contact your pediatrician or allergist for medical advice. Here are some things to know about fevers in children with food allergies.

Fevers and food allergy symptoms are both caused by immune system reactions.

1. Fever May Be a Sign of Infection

A fever can develop when the immune system is fighting a viral or bacterial infection. The immune system produces compounds known as pyrogens, which raise the body’s temperature to help fight off the infection and result in a fever. The heat caused by pyrogens is your body’s natural way of slowing the growth and reproduction of pathogens that can cause disease.

Ear infections, upper respiratory infections like the common cold, influenza (the flu), a sinus infection, or COVID-19 can cause common symptoms that are similar to symptoms of allergies, such as nasal congestion, coughing, sneezing, runny nose, watery eyes, or a sore throat. Gastrointestinal infections, whether caused by a parasite or a bacterial or viral infection, can also cause symptoms that may seem related to a food allergy, including abdominal pain or cramping, diarrhea, nausea, or vomiting.

One MyFoodAllergyTeam member wrote, “Allergies or sinus infection? I’m not sure.”

A urinary tract infection may also cause symptoms that look like food allergies, such as nausea, vomiting, and discomfort in the lower abdomen. In children under age 2, roseola, a viral infection, can cause a fever followed by a rash that may look like an allergic reaction.

Other symptoms of infections, such as body aches, yellow or green mucus, and fever, are generally not associated with allergies. However, it’s important to know that allergies can weaken the immune system, making the body more vulnerable to infections that may cause fever.

As another member shared, “My son is getting over a viral infection, caused by eczema, which is then caused by food allergies. Crazy cycle!”

2. Sunburn Can Cause a Fever

Sunburns can also cause a number of symptoms that may look like an allergic reaction, such as discolored skin (depending on skin tone) and blisters that may seem like a skin rash. Sometimes a sunburn can also cause a fever.

Overexposure to ultraviolet radiation from the sun damages the skin. This damage can trigger the immune system’s inflammatory response, similar to how it responds to an infection, which can cause fever and chills. If your child has a large sunburn, blistering, signs of dehydration, or fever, reach out to your doctor.

To help prevent sunburn, always apply sunscreen with an SPF of 30 or higher, have your child wear protective clothing, and seek shade to avoid direct sunlight whenever possible.

3. Fever Is a Side Effect of Some Medications

Certain medications can cause a drug-induced fever, which can be serious and requires immediate medical attention. Drugs that may cause fever include:

• Antipsychotics such as haloperidol and some antiemetics (used to treat nausea or vomiting)
• Selective serotonin reuptake inhibitors (SSRIs) and some other antidepressants
• Stimulant drugs such as amphetamines and methamphetamines, forms of which may be prescribed to treat attention-deficit/hyperactivity disorder
• Sulfa drugs, including some antibiotics and stool softeners

Always talk to your doctor about potential side effects of any medications to help you recognize any adverse reactions, such as a fever.

Certain medications — including some antidepressants, stool softeners, and stimulants — can cause fever as a side effect.

4. Some Vaccines Can Cause a Fever

Vaccines can also cause fevers in children. Vaccinations work by stimulating the immune system to create antibodies, among other immune responses, preparing the body to fight off future infections. A low-grade fever is a common side effect when a vaccine activates the immune system, and it usually goes away on its own.

5. Fever and Allergic Reaction May Occur at the Same Time

It’s possible to have symptoms of a food allergy at the same time as a fever from something else. This can be tricky to diagnose, especially if an infection or fever triggers symptoms like a rash or hives. Your child’s doctor likely will first rule out serious conditions, such as an infection. Once the fever is gone, allergy testing might be recommended to help pinpoint the cause.

It’s possible to have symptoms of a food allergy at the same time as a fever from something else.

One MyFoodAllergyTeam member shared their experience: “My 4-year-old granddaughter has been dealing with hives and fever for the last week. Parents are getting frustrated about not knowing what’s wrong,” they said. “Doctors have no answers so far. Waiting for blood work to come back. Hoping to get her tested for food allergies soon.”

If your child’s allergy symptoms overlap with a fever, be sure to talk to your health care provider. They can review your child’s medical history and may recommend blood tests or other evaluations to determine the cause of the fever.

When a Fever May Be an Emergency

Fever isn’t always bad — it’s part of the immune system’s process of fighting infection. However, there are times when a fever may require immediate medical attention. Contact your doctor immediately or seek emergency care if your child has a fever along with any of the following:

• A temperature over 102 F
• Extreme irritability or crying
• An unusual rash
• Sluggishness or extra drowsiness
• Severe headache or neck pain
• Trouble breathing
• Vomiting or nausea
• Seizure

If your child has food allergies, it’s important to discuss fever with your doctor to better understand the signs of a serious health condition. Your doctor can guide you on how to monitor symptoms in a child with food allergies, especially when a fever may be caused by something other than an allergy.

For children with serious food allergies, it’s essential to recognize the signs of anaphylaxis, a severe allergic reaction that can be life-threatening, and always carry emergency epinephrine.

Don’t hesitate to talk with a health care provider if you have questions or concerns about your child’s treatment plan. This may include over-the-counter medications like antihistamines and immunotherapy for immunoglobulin E-mediated food allergies. Learning more about food allergies and being prepared in case of an emergency can help you or your child navigate the challenges of living with food allergies.

Talk With Others Who Understand

MyFoodAllergyTeam is the social network for people with food allergies and their loved ones. On MyFoodAllergyTeam, more than 41,000 members come together to ask questions, give advice, and share their stories with others who understand life with food allergies.

Has your child had a fever that seemed linked to food allergies? What symptoms did you notice? Share your experience in the comments below, or start a conversation by posting on your Activities page.