Allergy symptoms typically include sneezing, watery eyes, a runny nose, or even a skin rash. Some allergens can even trigger allergic reactions known as anaphylaxis that are medical emergencies.

But can allergies cause a fever? Generally, no. Sometimes, however, allergy symptoms can make you vulnerable to a bacterial or viral infection. A bacterial or viral infection can lead to a fever, which you can indirectly blame on your allergy.

Common allergy symptoms

Your symptoms will depend on the cause of the allergy, known as an allergen. When you’re allergic to something, whether it’s dust, peanuts, or something else, your body reacts to the allergen by producing a chemical called a histamine. Depending on the individual and the particular allergen, symptoms can include:

  • a runny nose
  • itchy or watery eyes
  • sneezing
  • coughing
  • headache or sinus pain
  • sore throat
  • wheezing
  • post nasal drip

Nausea and diarrhea are common symptoms of certain food allergies. Swelling and skin rash are also signs of an allergic reaction.

When an allergic reaction is so severe that your breathing is jeopardized and you lose consciousness or are at risk of losing consciousness, it’s called anaphylaxis. Anaphylaxis is a medical emergency that requires immediate medical attention.

Fever with allergy symptoms

When you develop congestion, regardless of the cause, the buildup of mucus in your sinuses can be a breeding ground for bacteria. When an infection takes hold, you can be hit with a fever that can last for several days.

Congestion can be the result of sinusitis, allergies, or something more serious, such as the flu virus. It’s sometimes hard to know what’s causing your symptoms, because a cold or flu can mimic many of the signs of an allergy. The length of time and seasonal change can be important clues to tell your doctor.

Discovering exactly what is causing your symptoms, even if they’re mild, is important. Once you know the cause of your symptoms, you can start an effective treatment plan, and in the case of an allergy, you can take steps to prevent symptoms or flare-ups in the future. The key, however, is a proper diagnosis.

Learn more: Is it allergies or a cold? »


If you suspect your symptoms are the result of an allergy, you should see your primary care doctor. Your doctor may recommend seeing an allergist. An allergist is a specialist who can perform allergy tests and diagnose the source of your reaction. An allergist can also set up a treatment plan to reduce or prevent your symptoms.

Diagnosing an allergy requires a physical exam. Your doctor will also ask for a detailed personal medical history. A medical history can help your allergist find a connection between your symptoms and your exposure to allergens that may be triggering those symptoms. Keeping a log of when you have flare-ups can be very helpful to your physician to help identify a cause.

Your doctor may recommend a skin test to help diagnose your allergy. In this test, a tiny amount of an allergen, such as a dust mite or a particular food, is injected just under the skin. Your skin’s reaction reveals whether or not you’re allergic to that particular allergen. A blood test is also useful sometimes in pinpointing the cause of an allergy.

Read more: Allergies: Should I get a RAST test or a skin test? »

If an allergy is not the problem, an infection may be causing your fever. Conditions such as heat exhaustion can also cause a fever.


A bacterial infection usually needs antibiotics to eliminate a fever and other symptoms. A virus usually just needs time to resolve itself.

Treating an allergy often involves medications called antihistamines. These over-the-counter medicines block or lessen the amount of histamine produced in response to an allergen. Allergy shots and special types of steroids may also help reduce symptoms from an allergy. If you have seasonal allergies, an annual allergy shot may help you avoid symptoms when your allergens are in bloom.


Fevers tend to be temporary responses to an infection or other cause. Once the underlying cause, such as a cold or flu, is treated, the fever should disappear. If an allergy frequently leads to a bacterial infection, avoiding contact with those allergens is your best bet to stay healthy. If allergy shots are helpful for you, don’t skip the next one just because you’ve gone through a few pollen seasons without symptoms. Remember that the allergy shot is the thing that’s keeping you symptom-free.

If your allergy is to dust, certain foods, or animal dander, you may need to make adjustments in your home environment and lifestyle. If pollen is the culprit, pay close attention to air quality reports and forecasts for your area.

Tips for managing a fever

Managing a fever starts with taking an accurate temperature and knowing when a low-grade fever has advanced to one that requires medical attention. An oral digital thermometer held under the tongue can get an accurate reading in about 40 seconds. A rectal digital thermometer for babies takes about the same amount of time. If you have both kinds in your house, be sure to label them clearly and clean them well after each use with soap, cold water, and rubbing alcohol. Be sure to rinse the alcohol off thoroughly.

A normal temperature is 98.6° F (37° C). It can vary a degree higher or lower without any health concerns. For example, your temperature tends to be lower first thing in the morning and higher later in the afternoon. If your temperature reaches 100.4° F (38° C) or higher, it’s likely you have an infection and should get medical attention soon to begin treatment.

A high fever in an infant can be a life-threatening situation, so you should seek immediate medical attention if your baby’s temperature approaches 102° F (38.8° C).