When a child has a serious food allergy, any symptom — including a fever — can be alarming. Food allergies don’t cause fevers, but medical conditions with fevers can cause symptoms that resemble food allergies. Children with food allergies may have genes that make them more likely to develop asthma, hay fever, and other types of allergies, but hay fever doesn’t cause actual fever, either.

Children who are allergic to peanuts and other foods may experience a wide range of symptoms. They may develop:

• Skin reactions such as itching and hives
• Respiratory symptoms such as trouble breathing and coughing
• Gastrointestinal symptoms such as diarrhea and vomiting
• Other symptoms such as anxiety, heart palpitations, and changes in behavior

Read on to learn more about causes of fever in kids with food allergies and how to recognize when a fever might be an emergency.

Fever, Allergy, and the Immune System

A fever, medically known as pyrexia, occurs when the body’s normal temperature — typically between 97 and 99 degrees Fahrenheit — is more than half a degree warmer. There’s no universal threshold for fever, but 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 is running a high-grade fever.

Food allergies are also caused by the immune system reacting 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, but allergies do not trigger the release of inflammatory proteins associated with a fever.

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

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 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 or upper respiratory infections such as the common cold, influenza (the flu), a sinus infection, or COVID-19 can cause common symptoms that are similar to allergies, such as congestion, a cough, sneezing, runny nose, watery eyes, or a sore throat. A gastrointestinal infection that may be due to 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.

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

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

Other symptoms of infections aren’t generally associated with allergies, including body aches, yellow or green mucus, and fever. However, it’s important to know that allergies can take a toll on the body and may make someone more vulnerable to an infection that may cause a fever.

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

Read about how long symptoms of a reaction to food allergy last.

2. Sunburn Can Cause a Fever

Sunburns can cause a number of symptoms that may appear to be an allergy, such as red or discolored skin (depending on skin tone) and blisters that may seem like a rash. Sometimes a sunburn can also cause a fever.

Overexposure to ultraviolet radiation from the sun can damage skin. Similar to the body’s response to an infection, a sunburn can prompt the immune system to react with an inflammatory response that can cause fever and chills. If your child has a sunburn over a large area of their body, blistering, signs of dehydration, or fever, you should reach out to your doctor.

Always take care to avoid sunburn by applying sunscreen with an SPF of 30 or higher, wearing protective clothing, and seeking shade to avoid direct sunlight whenever possible.

3. Fever Is a Side Effect of Some Medications

Some 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 (which 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 discuss potential side effects of medications with your doctor to help you recognize adverse reactions, such as fever.

4. Some Vaccines Can Cause a Fever

Vaccines can also cause fevers in children. Vaccinations are designed to stimulate the immune system to create antibodies, among other immune responses, so that the body will be prepared to fight an infection if exposed in the future. A low-grade fever is a common side effect when a vaccine activates the immune system.

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

Symptoms of a food allergy and a fever due to another cause may occur simultaneously, which can be challenging to diagnose. In addition, infections and fevers can trigger rashes and hives. Your child’s doctor likely will first rule out serious conditions such as infections that may be causing the symptoms. Once the fever has resolved, allergy testing might be recommended.

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 with your health care provider. They can review your child’s medical history and may recommend blood tests or other evaluations to determine the fever’s cause.

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, contact your doctor immediately or seek emergency care if your child has a fever with symptoms such as:

• 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 bad nausea
• Seizure

If you have a child with food allergies, you may want to discuss fever with your doctor to better understand what may indicate a serious health condition and how best to monitor allergic reactions. Your doctor can advise you on how to monitor symptoms in a child with food allergies that coincide with a fever.

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

Never hesitate to talk with a health care provider if you have questions or concerns. Learning more about food allergies and being prepared in case of an emergency can help you or your child meet the challenges of living with this condition.

Find Your Team

MyFoodAllergyTeam is the social network for people with food allergies and their loved ones. On MyFoodAllergyTeam, more than 39,000 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 related to food allergies? Share your experience in the comments below, or start a conversation by posting on your Activities page.