Allergies do not cause a fever. In some cases, they may lead to health issues that can result in a fever, such as a sinus infection. Other conditions, such as bacterial or viral infections, can have similar symptoms to allergies and may cause a fever.
In this article, we discuss possible causes of fever and allergy symptoms.
We also look at the treatment options available and when to contact a doctor.
According to the American College of Allergy, Asthma, and Immunology, allergies do not cause a fever.
If a person is experiencing a fever alongside allergy symptoms, such as a runny or stuffy nose, the likely cause is a sinus infection.
Additionally, hay fever, or allergic rhinitis, does not cause a person to have a fever. Allergic rhinitis occurs as a reaction to triggers in the environment, such as pollen, mold, and pet dander.
Although allergic rhinitis does not cause a fever, people who have allergic rhinitis or asthma are more likely to develop chronic sinus infections, which can cause a fever.
The American Academy of Allergy, Asthma & Immunology note that this is because the presence of asthma or allergic rhinitis can lead to inflammation of the airways.
Symptoms of allergies can include:
- stuffy or runny nose
- watery, itchy eyes
- itchy nose and roof of the mouth
- shortness of breath
- tightness in the chest
- skin rashes and hives
Viral infections can cause a person to develop allergy-like symptoms alongside a fever.
One notable indication that a person has allergies is that allergy symptoms last only as long as people are experiencing an exposure to the allergen. Other causes, such as the flu or common cold, can last much longer.
Additionally, allergies cause a person to experience itchy and watery eyes. This does not typically occur alongside a cold or flu.
Sinusitis is the swelling of a person’s sinuses. These are hollow cavities in the face, around the cheeks, nose, and eye area. Mucus in the sinuses allows normal airflow.
However, if the sinuses become swollen, the mucus may not be able to drain properly and will build up.
Sinusitis typically occurs after an infection, such as the common cold or flu.
A person may develop a fever in cases of acute sinusitis.
Other symptoms of acute sinusitis can include:
- pain in the forehead and cheeks
- postnasal drip
- thick yellow or green discharge from the nose
The flu can cause similar symptoms to allergies because both conditions affect the respiratory system.
Having the flu can cause a fever that may last 3–4 days.
Other possible symptoms of the flu include:
- runny or blocked nose
- chest congestion
- sore throat
- body aches and pains
Itchy, watery eyes are more common with allergies than with the flu.
A common cold occurs due to an infection with a virus.
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Symptoms usually include:
- body aches
- blocked or runny nose
- sore throat
People may need to consult a doctor to diagnose the cause of a fever.
To find the underlying cause, a doctor will carry out a physical examination and take a medical history. They may also order additional tests, such as:
- blood tests
- stool and urine tests
- throat swab
- mucus sample
To diagnose an allergy, people may need to see an allergist. An allergist will take a full medical history and carry out certain tests.
Skin testing can indicate any sensitivities people have to common allergens, such as pollen, types of food, latex, or medications.
The Asthma and Allergy Foundation of America note that allergists may also do blood tests if people have a skin rash or are taking a medication that may interfere with skin test results.
Using medical history, physical examination, and results of various tests, an allergist will be able to diagnose an allergy. They will then be able to develop the most suitable treatment and management plan.
Treatment will depend on the underlying cause.
If a person is experiencing the flu or common cold, they may be able to treat symptoms with home remedies, such as:
- getting a lot of rest
- drinking plenty of fluids
- taking over-the-counter (OTC) pain relief medication, such as acetaminophen or ibuprofen
- using decongestants or nasal sprays to help reduce congestion
- avoiding alcohol and caffeine, as these may lead to dehydration
Additionally, a person can try applying a warm compress to the forehead and cheeks if they are experiencing painful pressure from sinusitis.
Learn more about home remedies and treatment options for sinusitis here.
To treat a fever, a person can:
- get plenty of rest
- drink a lot of fluids to avoid dehydration
- take OTC painkillers, such as ibuprofen or acetaminophen
Learn more about how to treat a fever at home here.
If a person has an allergy, they can work with a doctor or allergist to find a treatment plan that helps them manage their symptoms.
Treatment depends on the allergy but may include:
- corticosteroids to reduce inflammation in the nose
- immunotherapy, such as allergy shots or tablets
- avoiding known allergens, such as certain foods or medications
- wearing sunglasses or a face mask when around pollen or other allergens
- staying indoors during high pollen counts
- regularly cleaning bedding, floors, and other surfaces to reduce the amount of dust mites, mold, and pet dander
If a person is unsure about the cause of their symptoms, they should seek guidance from a healthcare professional.
They may also wish to contact a doctor if they have flu symptoms that last more than 10 days or if symptoms are not improving with OTC medication.
People should also speak with a doctor if the fever is causing:
- involuntary shivering, shaking, or teeth chattering
- high body heat with no sweat
- worsening symptoms
- hallucinations, confusion, or drowsiness
- skin rash
- muscle spasms
- increased heart rate
It is also advisable to consult a doctor if adults or children have a fever above 40°C (104°F).
People should seek emergency medical attention if they have symptoms of an extreme allergic reaction called anaphylactic shock. Symptoms include:
- difficulty breathing
- swelling of the throat or tongue
- losing consciousness
- a severe drop in blood pressure
Allergies cannot cause a fever, but they may indirectly lead to a fever if people develop a sinus infection.
Additionally, conditions such as viral infections, including the flu and common cold, can cause fever alongside allergy-like symptoms.
If a person has a persistent fever or allergy symptoms whose cause they are unsure of, they can contact a doctor for a diagnosis and treatment plan.