Can Allergies Cause a Fever?

Allergies, including hay fever (allergic rhinitis), do not cause a fever.1 Common symptoms of allergies include runny nose, sneezing, and watery eyes. If a fever does occur, the most common cause is sinusitis or a sinus infection.
This article will discuss other possible causes of fever and allergy symptoms.

What Causes Fever With Allergy-Like 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.2

The following conditions can cause both a fever and symptoms that are similar to allergies.
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.3
If your temperature reaches or exceeds 100.4 degrees Fahrenheit (38 degrees Celsius), this is considered a fever.3

If you have other symptoms in addition to a fever, call your healthcare provider.
Sinusitis
Sinusitis, or sinus infection, causes inflammation and swelling of your sinuses. Acute sinusitis can be triggered by a cold or allergies and may lead to a fever.
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.
Other symptoms of sinusitis can include:4

• 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.5
Commonly, the flu can cause a fever that lasts for three to four days.2 Other symptoms of the flu may include:5
• 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.6
Although it is rare, a cold can cause a fever.7 Other symptoms of a cold can include:
• Headaches
• Sneezing
• Stuffy or runny nose
• Body pain
• Cough
• Sore throat

Allergy 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