Can Allergies Cause a Fever?

Dr. Menachof, MD, has specialized in conditions around the head, throat, ear, nose, neck and face for over 20 years, and was the first to bring sublingual allergy drops to Colorado in 2005. He has been recognized as a Fellow by multiple academies, named one of America’s Top Facial Plastic Surgeons continually since 2003 and is featured in multiple national publications.

Experiencing a fever with your allergies? Learn more about what causes this and how you can get your allergies treated in Denver.

The short answer is — no — allergies do not directly cause a fever. A high temperature is a sign that your body is fighting a bacterial or viral infection. Sometimes allergies can lead to a sinus infection, and a fever is a symptom of a sinus infection, so allergies can indirectly cause a fever.

Can Allergies Cause Fever?

According to the American College of Allergy, Asthma, and Immunology, allergies do not cause a fever.

Despite its name, hay fever has nothing to do with hay and it doesn’t actually cause a fever. Hay fever, or allergic rhinitis, is simply an allergic reaction to seasonal allergens that can cause sneezing, nasal congestion, itchy or watery eyes, and a sore throat.

If you’re experiencing a fever in addition to allergy symptoms, like a runny nose or itchy eyes, it’s typically because chronic congestion in your nose has led to a sinus infection. People who suffer from allergic rhinitis are far more likely to experience chronic sinus infections, which often trigger fevers.

Common Allergy Symptoms

Seasonal allergies cause a variety of symptoms that vary based on the specific allergen and the severity of your reactions. Common environmental allergens include pollen, pet dander, dust mites, and mold. Allergy symptoms can include:

Food allergies can cause nausea and upset stomach. Skin rashes and hives are also a sign of an allergic reaction.

What Causes Allergy Symptoms & Fever

Regardless of the cause, when you experience nasal congestion, mucus accumulates in your sinuses and can provoke bacterial growth. This bacteria buildup can lead to an infection, which causes a slew of symptoms, including a fever.

Many conditions can cause congestion and other allergy-like symptoms, including sinusitis, the common cold, the flu, or COVID-19. These conditions are easy to confuse with seasonal allergies, so it can be difficult to determine the actual cause of your congestion and fever.

Once you uncover the source of your symptoms, you can treat accordingly. Here’s what to look for with each of these congestion and fever-inducing ailments:


Sinusitis is simply swelling in your sinuses, the hollow cavities in your face, cheeks, nose, and eye area. If the sinuses become swollen, mucus begins to build up and block these passages. Common symptoms of acute sinusitis include:

  • Pain in the forehead and cheeks
  • Fever
  • Post-nasal drip
  • Thick discharge from the nose (usually yellow or green)
  • Congestion
  • Coughing
  • Toothache


The flu can cause a fever that lasts up to four days. Other potential symptoms include:

  • Runny nose
  • Chest congestion
  • Cough
  • Sore throat
  • Headache
  • Fatigue
  • Body aches and pains

Common Cold

A common cold is a virus, and sometimes (though not often) can cause a fever and chills. Symptoms typically include:

  • Body aches
  • Headache
  • Sneezing
  • Congestion
  • Coughing
  • Sore throat


COVID-19 is a viral illness that affects people in different ways. A fever and chills are very common symptoms of COVID-19. Other symptoms include:

  • Cough
  • Difficulty breathing
  • Fatigue
  • Headache
  • Loss of taste or smell
  • Sore throat
  • Congestion
  • Nausea or vomiting
  • Muscle or body aches
  • Diarrhea

How to Tell if Your Symptoms Are Due to Allergies

You may need to consult a doctor to determine the cause of your fever. A doctor will ask you questions and do a physical exam to understand symptoms and onset. Other tests can include a blood test, a stool or urine test, a throat swab, a mucus sample, or an x-ray.

If you suspect your symptoms are due to an allergy, you should make an appointment with a doctor. Your doctor may recommend consulting an allergist, someone who can test for and diagnose specific allergies.

Diagnosing an allergy requires several steps. These may include:

  1. A detailed personal medical history. This can help your allergist find a connection between your symptoms and potential exposure to the allergen.
  2. Keeping a log. By noting when your symptoms appear, intensify, or disappear, your allergist can start to determine potential allergens and seasons that trigger symptoms.
  3. Allergy testing. Usually, allergists use a skin prick test (or scratch test) to test for multiple allergens at one time. Your skin’s reaction to particular allergens will help determine what you’re allergic to. Other common types of allergy tests include intradermal, skin patch, and blood tests.

Treating Fever & Allergies

If a bacterial infection is the cause of your fever, a doctor will prescribe antibiotics to eliminate symptoms. A virus will usually disappear on its own, within a week or two.

If you have sinusitis, a cold, the flu, or COVID-19, your doctor will recommend staying home, resting, hydrating, taking over-the-counter (OTC) medications, using decongestants, and placing warm compresses on the sinuses.

If allergies are the root of your symptoms, there are many treatment options. Your doctor will work with you to prescribe a treatment plan based on your symptoms and specific allergens. Treatment may include:

Lifestyle Changes

The simplest and most cost-effective way to treat your allergies is by making some lifestyle changes to reduce exposure to your specific allergens. This can include things like purifying the air in your home, vacuuming and dusting regularly, taking natural supplements, and using nasal irrigation.


Allergy medications come in many forms, including pills, liquids, nasal sprays, and eye drops. These are available over the counter (OTC) and by prescription, and can help ease symptoms like congestion, itchy and watery eyes, runny nose, and sneezing. An allergy specialist can help you determine which medications will work best for you.

Allergen Immunotherapy

Allergen immunotherapy — allergy shots and allergy drops — is a long-term allergy treatment that helps decrease your body’s response to allergens. It works by gradually introducing your body to your specific allergens (either through a shot or through drops under the tongue), allowing your body to gradually develop tolerance to the allergen.

When to See a Doctor

If your fever is above 104°F (40°C), contact a doctor immediately. If you have flu symptoms that last more than 10 days or if your symptoms aren’t improving with OTC medications, you should contact a doctor.

You should also see a doctor if your fever is causing:

  • High body heat with no sweat
  • Involuntary shivering or shaking
  • Worsening symptoms
  • Hallucinations or confusion
  • Skin rashes
  • Muscle spasms
  • Increased heart rate
  • Vomiting

Seek emergency medical attention if you have symptoms of an extreme allergic reaction or anaphylactic shock. Symptoms include:

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

Get Help

While allergies don’t directly cause a fever, they may lead to sinus infections. And other conditions — like the flu and common cold — can be mistaken for allergies. If you are experiencing persistent allergy symptoms or a fever, you should contact a doctor to find out what’s causing your discomfort.

Our staff at Advanced ENT & Allergy Center can help you determine the cause of your allergies and offer a treatment plan that will help you experience relief from your allergy symptoms. Book a consultation today.