Can Allergies Raise Your Body Temperature?

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Common symptoms of allergies include a runny nose, sneezing, and watery eyes. Allergies, including hay fever (allergic rhinitis), do not cause a fever. If a fever does occur, the most common cause is sinusitis, or a sinus infection

It is rare to experience a fever with allergic rhinitis, but it could happen. Allergic rhinitis can lead to airway inflammation, which can cause a fever.

Sneezing and checking body temperature

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Allergies Symptoms

Allergy symptoms depend on the trigger, or allergen. Your body produces a chemical known as histamine, which is responsible for the reactions you experience. 

Symptoms of allergies can include:

  • Sneezing
  • Runny nose
  • Itchy eyes
  • Headache 
  • Sore throat
  • Wheezing
  • Coughing
  • Fatigue
  • Nausea and diarrhea (can occur in some food allergies)
  • Skin rash

Hay Fever Symptoms

Hay fever, also known as allergic rhinitis, is caused by an allergic reaction to allergens like pollen, mold, dust mites, and furs and feathers from animals.

It may look like a person has a cold when they have hay fever because they have symptoms like a runny nose, itchy eyes, congestion, sneezing, and sinus pressure, which are similar to symptoms of a cold. However, people with hay fever do not typically develop a fever.

Fever and Allergies Symptoms

The most common sign that you have an allergy is that it is short-lived and persists only as long as you are exposed to the allergen. If your symptoms persist, it may be that you have the flu or the common cold since they typically last longer.

However, itchy and watery eyes, which are common in allergies, are not signs of the flu or a cold.

Sinusitis

Sinusitis, or sinus infection, causes inflammation and swelling of your sinuses. Sinuses are spaces in your head located around the cheeks, nose, and eyes. The sinuses secrete mucus that drains out through the nose. This drainage helps keep the nose clean and prevent infection.

Your sinuses are normally filled with air, but when they become blocked or swollen, the mucus may not be able to drain out and will build up. Bacteria can then grow and cause an infection, resulting in sinusitis. 

Acute sinusitis may lead to a fever. It can be triggered by a cold or allergies. Other symptoms of sinusitis can include:

  • Postnasal drip (mucus drips down the throat)
  • Nasal discharge (thick yellow or green discharge from the nose) or stuffy nose
  • Facial pressure (particularly around the nose, eyes, and forehead), headache, and pain in your teeth or ears
  • Halitosis (bad breath)
  • Cough
  • Tiredness

Flu

Flu is a contagious respiratory illness caused by influenza viruses that infect the nose, throat, and sometimes the lungs. Flu usually comes on suddenly.

Commonly, the flu can cause a fever that lasts for three to four days. Other symptoms of the flu may include:

  • Runny or stuffy nose
  • Chest congestion
  • Cough
  • Sore throat
  • Headache
  • Fatigue
  • Body aches 

Common Cold

A cold is a contagious upper respiratory infection that affects your nose, throat, sinuses, and trachea (windpipe). More than 200 different viruses can cause a cold, but the most common virus causing colds is the rhinovirus.

Although it is rare, a cold can cause a fever. Other symptoms of a cold can include:

  • Headaches
  • Sneezing
  • Stuffy or runny nose
  • Body pain
  • Cough
  • Sore throat

Diagnosis

You may need to consult your doctor to find out the cause of your fever. Your doctor will perform a physical exam and check your medical history. They may also run other tests like:

  • Blood tests
  • Stool and urine analysis
  • Mucus sample
  • Throat swab
  • X-rays

For allergies, you may need to see an allergist. They will likely perform skin or blood tests to figure out which environmental allergies you have, such as pollen, dust mite, cat, or dog. Blood testing will likely be preferred if you are taking drugs that may interfere with skin test results.

Treatment

If you have the flu or the common cold, certain home remedies can help treat symptoms, including:

  • Resting
  • Staying hydrated
  • Taking pain relief medication, like acetaminophen or ibuprofen
  • Using nasal sprays to reduce congestion
  • Avoiding alcohol and caffeine

For sinusitis, in addition to these measures, you can apply a warm compress to your forehead and cheeks if you are experiencing painful pressure.

Treating allergies depends on the allergen involved, but other treatment options include: 

Fever

Normal body temperature ranges from about 97 degrees Fahrenheit (36.1 degrees Celsius) to 99 degrees Fahrenheit (37.2 degrees Celsius), with the limit of 1 degree higher or lower. You have a fever if your temperature reaches or exceeds 100.4 degrees Fahrenheit (38 degrees Celsius). You may need additional medical care and should reach out to your physician if you have other symptoms that warrant medical attention.

When to See a Doctor

Consult your doctor if you are not sure what's causing your symptoms, if you have flu symptoms that linger for more than 10 days, or if your symptoms don’t subside with over-the-counter medications.

Speak with a doctor if the fever causes:

  • Involuntary shivering
  • High body heat with no sweat
  • Worsening symptoms
  • Skin rash
  • Muscle spasms
  • Nausea
  • Confusion or drowsiness

It is recommended that you seek help if you or your kids have a fever above 40 degrees Celsius (104 degrees Fahrenheit).

Seek immediate medical help if you experience an extreme allergic reaction like anaphylaxis since it can be fatal. Symptoms of anaphylaxis can include:

  • Difficulty breathing
  • Swelling of the throat or tongue
  • Vomiting
  • Diarrhea
  • Loss of consciousness
  • Severe drop in blood pressure
  • Hives

Summary

Allergies do not cause a fever, but they can trigger a sinus infection that can cause a fever. Viral infections that cause the flu and the common cold can cause a fever. Seek medical help if you have a lingering fever for an accurate diagnosis and treatment options.

A Word From Verywell

Allergies are common, but they can be managed. By trying home remedies and taking the right medications, you’ll have it under control in no time. However, it is recommended that you check with your doctor for better treatment plans. If symptoms persist, seek immediate medical help.

Frequently Asked Questions

  • Why can allergies cause fever?

    Allergies do not normally cause a fever. However, they can trigger a sinus infection by causing swelling in the sinuses and a buildup of mucus, allowing bacteria to grow. If you have a sinus or viral infection, you may develop a fever.

  • What is a low-grade fever?

    A body temp between 100.4 and 102.2 degrees Fahrenheit is usually considered a low-grade fever. 

  • How long does a fever last?

    A fever typically lasts for about one to three days. However, persistent fever can last for about 10 days.

  • Are low-grade fevers contagious?

    Low-grade fevers are not always contagious, but the CDC recommends you stay home until your fever is gone.

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8 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. American College of Allergy, Asthma, & Immunology. Fever.

  2. NIH News in Health. Cold, flu, or allergy? Published October 2014.

  3. Cleveland Clinic. Sinus infection (sinusitis). Updated June 4, 2020.

  4. Centers for Disease Control and Prevention. Key facts about influenza (flu). Updated August 26, 2021.

  5. Cleveland Clinic. Common cold. Updated April 30, 2020.

  6. Centers for Disease Control and Prevention. Cold versus flu. Updated September 16, 2021.

  7. MedlinePlus. Body temperature norms. Updated January 16, 2021.

  8. American Academy of Allergy, Asthma & Immunology. Anaphylaxis

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