Clarifying Health Myths: Can Allergies Cause Fever?

You’ve been sneezing, have a stuffy nose, and your eyes are watery. You thought your symptoms were due to seasonal allergies, but now you’ve developed a fever. Can allergies cause a fever? This article will discuss what allergies are, outline common symptoms, discuss possible treatment options, and explore what it could mean if a fever is present with allergy symptoms.

Understanding allergies

An allergy is when your body’s immune system recognizes something as foreign and harmful to your body and overreacts to it. In response to this, your body produces symptoms known as an allergic reaction. The substance your body reacts to is known as an allergen.

When the body reacts to an allergen, the immune system produces antibodies known as immunoglobulin E or IgE. This activates mast cells and basophils, which activate an inflammatory response by releasing histamine. This response produces a systemic allergic reaction.

Allergens can enter your body by breathing them in through your nose and lungs, ingesting them through food and medicine that you eat and swallow, injecting them from an insect sting or medication, and absorbing them through your skin.

If an allergy is severe, it can cause anaphylaxis. Anaphylaxis can cause the following:

  • Skin rash or hives
  • Swelling of the lips, tongue, and throat
  • Shortness of breath
  • Wheezing
  • Dizziness
  • Stomach pain, bloating, vomiting, or diarrhea
  • Uterine cramps
  • Feeling of impending doom

Anaphylaxis is the most severe form of an allergy and is a medical emergency. Studies have shown that allergies cause inflammation, which can lead to nasal obstruction, fluid accumulation, bacterial infection, and acute disease. When allergy symptoms are not resolved, it can lead to the development of other illnesses, which can cause a fever. However, the allergy itself does not cause a fever.

Types of common allergies

There are different allergens that can cause allergic reactions. The most common types of allergies include:

  • Seasonal allergies
  • Allergies to medications
  • Food
  • Latex
  • Mold
  • Pet dander
  • Venom

Seasonal allergies occur during specific times of the year. People with spring allergies may react to the increased pollen in the air due to trees and flowers blooming. In the fall, ragweed and weeds are more prevalent and can cause allergy symptoms for those with fall allergies.

Allergies to foods are usually developed in childhood but can also develop in adulthood. Fish, peanuts, shellfish, and tree nuts are the most common food allergies. When someone has a food allergy, their immune system overreacts to a protein found in that food, which can be life-threatening if anaphylaxis occurs.

While latex isn’t as widely used as it once was, it can be found in things like rubber gloves, condoms, balloons, toys, and rubber bands. Latex allergy sufferers are often allergic to bananas, avocados, tomatoes, or chestnuts. The allergic reaction worsens with increased exposure to the allergen.

Pet dander allergies are most commonly associated with cats and dogs. Pet dander is the flakes of skin shed by a pet. When a person who is allergic to pet dander comes in contact with it, they can experience an allergic reaction and may even develop dermatitis.

Symptoms of allergic reactions

Allergies can cause a variety of symptoms that may mimic other illnesses. This can make diagnosing the allergy challenging. Common allergy symptoms include the following:

  • Runny nose
  • Congestion
  • Sneezing
  • Wheezing
  • Shortness of breath
  • Cough
  • Rash
  • Fatigue
  • Headache
  • Nausea and vomiting

It is important to be able to differentiate allergy symptoms from other illnesses. Understanding your symptoms and how to treat them is important because it allows you to treat your symptoms appropriately and prevents unnecessary medications.

Allergies, colds, and the flu all trigger an immune response in the body. The body will recognize the allergen, virus, or bacteria in the body as something foreign and develop antigens to essentially fight the foreign substance and get rid of it. However, you can differentiate between allergies, colds, and the flu based on the symptoms produced and the length of the symptoms. Cold and flu symptoms usually last three to five days and rarely last beyond two weeks. Allergy symptoms will last as long as you are exposed to the allergen, which could be as long as six weeks or more. Some people suffer from seasonal allergies, whereas others might have allergy symptoms year-round.

Can allergies cause fever?

Allergies do not cause a fever directly but can increase your risk of becoming ill with a viral or bacterial infection. Those infections can cause a fever. Having a fever could be related to one of the following:

  • Bacterial or viral infection
  • Extreme sunburn
  • Heat stroke
  • Inflammatory diseases like rheumatoid arthritis

If you have common signs of allergies with a fever, further evaluation may be needed to treat an infection or other health issue.

What can cause allergy symptoms and fever?

Because allergies and other illnesses can cause many of the same symptoms, it is important to understand what illnesses can cause allergy symptoms with a fever so you can receive appropriate treatment.


Sinusitis, also known as a sinus infection, can cause a runny and stuffy nose, facial pain and pressure, headache, post-nasal drip, sore throat, cough, bad breath, and a fever. It occurs when fluid builds up and gets trapped in the sinus cavities, creating a breeding ground for bacteria that cause infection.

If you’ve been experiencing symptoms of a sinus infection for 10 days or more and are feeling worse instead of better, you should consult with your healthcare provider. Your healthcare provider will examine you and ask you questions to determine if you have sinusitis. If it is determined you have sinusitis, you will be prescribed antibiotics to treat it. Make sure you take your antibiotics as prescribed and take the entire course of antibiotics to clear the infection. Stopping the antibiotics before they are gone can result in the infection coming back and can cause antibiotic resistance.


The flu is a respiratory illness caused by the influenza A or influenza B virus. Symptoms of the flu can be mild or severe and include:

  • Fever
  • Cough
  • Sore throat
  • Runny nose
  • Congestion
  • Muscle and body aches
  • Headache
  • Fatigue

Flu symptoms usually last three to four days and are more common during colder months of the year. This can help differentiate flu symptoms from allergies because allergies often last longer and do not cause a fever. A rapid influenza test can be done to test for influenza A and B. This test utilizes a sample of mucus and secretions from the nose and throat. A healthcare professional will use a sterile swab to collect the sample from your nose or throat.


The common cold is also a respiratory illness that has symptoms similar to the flu but is usually less severe, without a fever, severe fatigue, and body aches. Common cold symptoms include:

  • Mild fatigue
  • Sneezing
  • Chest discomfort
  • Cough
  • Stuffy nose
  • Sore throat
  • Fever (more common in children)

The common cold is less likely to result in serious illness and usually lasts 7–10 days before symptoms improve.


COVID-19 is a contagious respiratory virus caused by infection with the SARS-CoV-2 coronavirus. Common symptoms of COVID-19 include:

  • Sudden fever or chills
  • Cough
  • Shortness of breath
  • Loss of taste or smell
  • Sore throat
  • Congestion or runny nose
  • Fatigue
  • Muscle or body aches
  • Nausea and vomiting
  • Diarrhea
  • Headache

While symptoms of COVID-19 are very similar to allergies, the common cold, and the flu, you can determine if you have COVID-19 by testing for it at home or at a healthcare facility.

Recognizing allergies

It is important to recognize when symptoms are related to allergies so proper treatment can be given. Allergy testing may be recommended to determine if symptoms are due to an allergy or something else.

The most common type of allergy testing is skin testing. This involves placing a small amount of a suspected allergen on the skin. A healthcare professional will prick the skin, allowing the substance to move under the skin. That area should not be touched, rubbed, or scratched after the skin is pricked. After 15 minutes, the skin is assessed for any signs of a reaction, including redness and swelling.

Another skin test is the patch test, which is done to determine a contact allergy. For this test, a patch with a suspected allergen is placed on the skin. After the patch is worn for 48–72 hours, the skin will be assessed for a reaction.

Blood tests can also be done to check for an allergy by drawing an immunoglobulin E (IgE) level, which measures the total level of IgE present in the body. An elevation in IgE indicates an allergy, but it is unable to determine what the allergy is to. The higher the IgE level is, the more severe the allergy is.

A complete blood count (CBC) may also be drawn to check your white blood cell (WBC) count. Allergies increase your WBC count. However, there are other reasons a WBC count may be elevated. If your WBC count is elevated, your healthcare provider will determine the cause of this.

Your healthcare provider may also recommend elimination testing. This involves avoiding food or other suspected allergens to determine if your symptoms resolve. If symptoms resolve with elimination testing, you are likely allergic to that allergen.

Treating allergies

There are several treatment options for treating and preventing allergies. The best way to reduce your allergy symptoms is to avoid the allergen. Your healthcare provider may also recommend medications to help manage your allergy symptoms that may include the following:

  • Antihistamines (oral medication, eye drops, injections, or nasal sprays)
  • Corticosteroids (creams and ointments, eye drops, nasal sprays, inhalers, oral pills, or injections)
  • Decongestants
  • Allergy shots
  • Leukotriene inhibitors

To conclude, allergies can cause a lot of unwanted symptoms that make you feel unwell. However, they do not cause a fever. If you have allergy symptoms with a fever, it is possible that you developed a viral or bacterial infection, and you should consult with your healthcare provider. It is important to be able to differentiate between allergy symptoms and symptoms of other illnesses so that you can receive the proper treatment. Always consult your healthcare provider before taking any over-the-counter medications to make sure it is an appropriate treatment method for you.


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