Table of ContentsView AllTable of ContentsCausesSymptomsDiagnosisTreating AllergyTreating FeverWhen to Get Help
Table of ContentsView All
View All
Table of Contents
Causes
Symptoms
Diagnosis
Treating Allergy
Treating Fever
When to Get Help
Allergies, including hay fever (allergic rhinitis), do not generally cause a fever.However, allergies can cause inflammation in the nose and sinuses, which can sometimes lead to sinusitis (sinus infection). When this happens, you might develop alow-grade fever(99°F to 100.4°F), but the fever is due to the infection, not the allergy itself.
If you develop a fever alongside allergy symptoms, it’s worth considering other causes or a possible infection. The most common cause is a sinus infection, which might lead to other symptoms like pressure around the nose, eyes, and forehead. The flu, common cold, or COVID-19, could also be at play.
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What Causes Fever with Allergies?
Typical allergy symptoms include sneezing, runny nose, and itchy eyes—but not fever.
Fever is the body’s immune response to an infection. When the body detects harmful invaders, particularly bacteria or viruses, immune cells release substances called pyrogens, which signal to the brain to raise body temperature. Fever helps the body fightpathogensoff, as many pathogens struggle to survive in the hotter environment.
Allergiesdon’t work the same way. Allergy symptoms happen when your body overreacts to a perceived invader, such as pollen, pet dander, or dust. This overreaction causes the body to release histamines and other inflammatory compounds that lead to a cluster of allergy symptoms.The release of fever-causing pyrogens is not part of this immune response.
If you develop fever in addition to allergy symptoms, the most common reason is one of the following infections.
FeverNormal body temperature ranges from 97 degrees Fahrenheit (36.1 degrees Celsius) to 99 degrees Fahrenheit (37.2 degrees Celsius), with the limit of 1 degree higher or lower.If your temperature reaches or exceeds 100.4 degrees Fahrenheit (38 degrees Celsius), this is considered a fever.If you have other symptoms in addition to a fever, call your healthcare provider.
Fever
Normal body temperature ranges from 97 degrees Fahrenheit (36.1 degrees Celsius) to 99 degrees Fahrenheit (37.2 degrees Celsius), with the limit of 1 degree higher or lower.If your temperature reaches or exceeds 100.4 degrees Fahrenheit (38 degrees Celsius), this is considered a fever.If you have other symptoms in addition to a fever, call your healthcare provider.
Normal body temperature ranges from 97 degrees Fahrenheit (36.1 degrees Celsius) to 99 degrees Fahrenheit (37.2 degrees Celsius), with the limit of 1 degree higher or lower.
If your temperature reaches or exceeds 100.4 degrees Fahrenheit (38 degrees Celsius), this is considered a fever.
If you have other symptoms in addition to a fever, call your healthcare provider.
Sinusitis
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 prevents 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.
Othersymptomsof sinusitis can include:
Flu
Commonly, the flu can cause a fever that lasts for two to four days. Othersymptomsof the flu may include:
Common Cold
A cold is a contagious upper respiratory infection that affects your nose, throat, sinuses, andtrachea(windpipe).
More than 200 different viruses can cause a cold. The most common virus causing colds is the rhinovirus. These viruses mostly cause colds in the winter. However,non-polio enteroviruses, the second most common cause of colds, are most active in summer. These viruses are known for causing fever.
Other symptoms of a cold can include:
COVID-19
Low-grade fever is one of the most common signs of COVID-19, and usually one of the first. Not everyone with COVID develops a fever. When it does occur, it usually appears within two to 14 days after exposure to the coronavirus.
Like the cold and flu, COVID infections are most common in the fall and winter when the weather is colder and people spend more time indoors. That said, it’s not unusual for COVID surges to occur during the summer months when outdoor allergies peak.
Other common symptoms of COVID include:
Allergy Symptoms
Hay fever often causes flu-like symptoms, such as runny nose, itchy eyes, congestion, sneezing, and sinus pressure. However, despite its name, fever is not one of them.
The exact allergy symptoms you experience depend on the trigger, or allergen.Symptoms of allergiesmay also include:
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:
For allergies, you may need to see anallergist. They will likely performskin or blood teststo figure out which environmental allergies you have, such as pollen, dust mite, cat, or dog.
Treating Allergies
Treating allergies depends on the allergen involved, but options include:
Treating a Fever
If you have the flu or the common cold, certain home remedies can help treat symptoms, including:
For sinusitis, in addition to these measures, you can apply a warm compress to your forehead and cheeks if you are experiencing painful pressure.
When to See a Healthcare Provider
Consult your healthcare provider 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.
See a healthcare provider right away if you have a fever in addition to any one of these symptoms:
Get immediate medical attention if the fever reaches these levels based on age:
You should also get immediate medical help if you experience an extreme allergic reaction likeanaphylaxissince it can be fatal. Symptoms of anaphylaxis can include:
Summary
Allergies do not cause a fever, but they can trigger a sinus infection that can cause a fever. Viral infections that cause fever, such as the flu, common cold, and COVID-19, could also be at play. Contact a healthcare provider for an accurate diagnosis and treatment options if you develop a persistent or high fever in addition to allergy symptoms.
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Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.American College of Allergy, Asthma, & Immunology.Fever.El-Radhi AS.Pathogenesis of fever.Clin Manual of Fever in Children. 2019 Jan;1(1):53-68. doi:10.1007/978-3-319-92336-9_3Yale Medicine.Seasonal allergies (allergic rhinitis).MedlinePlus.Body temperature norms.Penn Medicine.Sinus infection (sinusitis).Mount Sinai.Sinusitis.Centers for Disease Control and Prevention.Key facts about influenza (flu).Penn Medicine.Flu (influenza).Centers for Disease Control and Prevention.About non-polio enteroviruses.Centers for Disease Control and Prevention.Symptoms of COVID-19.Johns Hopkins Medicine.COVID symptoms - frequently asked questions.Johns Hopkins Medicine.Food allergies.David A, Quinlan J.Fever of unknown origin in adults.Am Fam Phys. 2022;105(2):137-143.American College of Allergy, Asthma, & Immunology.Testing & diagnosis.American College of Allergy, Asthma, & Immunology.Hay fever.Harvard Health Publishing.Fever in adults: When to worry.Stanford Medicine.Reye syndrome in children.CHI Saint Joseph Health.What is considered a fever? - When to call a doctor.Boston Children’s Hospital.Fever in children.American Academy of Allergy, Asthma & Immunology.AnaphylaxisAdditional ReadingFever. ACAAI Patient.Cold, flu, or allergy?NIH News in Health.Sinusitis| aaaai. Org.Allergy diagnosis| aafa. Org.Cold versus flu. Centers for Disease Control and Prevention.
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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Fever. ACAAI Patient.
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Cold versus flu. Centers for Disease Control and Prevention.
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