Can Allergies Cause Fever?

Those with allergies are at a consistent risk of becoming sick if they are exposed to the allergen they are sensitive to. Many people have varying allergies that can cause numerous symptoms, such as headache, cough, and congestion of the nasal passage. In more extreme reactions, individuals may also experience bouts of fatigue. The symptoms of an allergic reaction are very similar to that of a cold or flu, but can allergies cause fever?This article will answer that question and supply you with information to help you ascertain the difference between allergic reactions and other common conditions like a cold or flu.

Can Allergies Cause Fever?

The simple answer is no. A fever is when an individual’s body temperature rises (to above 100.4°F). Many conditions can lead to one developing a fever, although allergic reactions generally do not. If you are experiencing the symptoms of a seasonal allergy as well as a fever, then the cause of your symptoms is most likely a viral infection, not allergies. A viral infection of the upper respiratory system will cause an individual to develop many of the same symptoms as seasonal allergies, but with an accompanying fever. These infections should clear up on their own, without the need of medical or medicinal intervention, although some medication may be useful in subsiding symptoms.

If the infection does not clear up on its own and remains persistent, or if new symptoms form, then it would be wise to consult a health care professional as soon as possible. A useful tip to help with diagnosis and treatment is to record your body temperature from the time you begin to feel ill, as this information will be of great value to your health care provider.

More About Seasonal Allergies/Hay Fever

When an individual who suffers from allergies is exposed to the allergen that they are sensitive too, their symptoms can come on suddenly, and remain persistent for as long as they remain exposed to the allergen. Other symptoms one may notice include:

  • Sneezing
  • Runny nose
  • Itchy nose
  • Itchy throat
  • Itchy, red, and or watery eyes (allergic conjunctivitis)

In some cases an allergy can progress and cause an individual to develop asthma, this will be telling with shortness of breath and/or wheezing.

How to Tell Allergy from Cold

Now that we know the answer to the question: can allergies cause fever, here's how to tell what’s behind the fever. The key difference between an allergic reaction and a cold is the cause.


Colds, and similar conditions, are caused by a viral infection. A virus is a living organism that infects an individual and causes the symptoms commonly associated with a cold. These viral infections are contagious and can spread from person-to-person, or by touching a surface that has been exposed to the virus. Colds are usually eradicated after a couple of weeks by the body's immune system, which attacks and kills the virus.


Allergies, however, are not caused by a virus and are not contagious. Allergies are caused by over-active immune systems. It is a result of an individual’s immune system mistakenly assuming that common, harmless particles, such as pollen or dust, are in fact germs. This leads to the immune system attacking them, and releasing chemicals such as histamine, to assist the eradication of the harmless particles. This is what causes the symptoms often associated with having a cold, as the release of chemicals causes inflammation in the nasal passageway, and lead to sneezing, sniffing, and other symptoms.

Below is a table to help you identify more differences between allergies and colds:




Duration of the condition/symptoms

Days, weeks, or months – as long as you are exposed to the allergen

Three to fourteen days

Time in which the condition forms

Any time of the year (although some allergens are environmental and seasonal)

Any time of the year, but most commonly in the winter months

Time in which symptoms are noticed

Symptoms appear almost instantaneously after one been exposed to a particular allergen

Symptoms take several days to appear after infection has occurred

Common symptoms

  • Cough (sometimes)
  • Stuffy or runny nose (often)
  • Body aches (never)
  • Fever (never)
  • Fatigue (sometimes)
  • Sore throat (sometimes)
  • Itchy and water eyes (often)
  • Cough(often)
  • Stuffy or runny nose (often)
  • Body aches (sometimes)
  • Fever (sometimes)
  • Fatigue (sometimes)
  • Sore throat (often)
  • Itchy and water eyes (rarely)

 The most noticeable difference between an allergic reaction and a cold is the duration in which it lasts. A cold generally lasts no longer than two weeks, meaning any symptoms lasting longer than that period of time will likely indicate an allergic reaction or other complication.

Allergy Diagnosis and Treatments


It is generally quite simply for a health care professional to deduct whether an individual is suffering from allergies. Allergies are often easy to identify as they usually appear around the same time of year. Diagnosis will general involve the asking of questions about your symptoms, such as when they appeared and how quickly, as well as a physical exam. If a diagnosis is not reached after these examinations, then you will likely be referred to an allergist, who will administer a blood or skin test. A skin test is generally performed as follows:

  1. A miniscule amount of the suspected allergen is injected just under the skin (this may slightly sting but shouldn’t be very painful)
  2. Your health care provider will wait fifteen minutes, to see if there is any reaction
  3. If a lump appears around the injected area, similar to that of a mosquito’s bite, then the test has yielded a positive result

Even if the skin and or blood test yields a positive result, an individual must also show symptoms of having an allergy to be diagnosed with one. This means that if a child, for example, tested positive for being allergic to grass pollen, but shows no signs or symptoms when amongst grass, then they cannot be definitely diagnosed with the allergy.


There is currently no known cure for seasonal or environmental allergies, but there are steps you can take to reduce the effect of symptoms. The first step to take is to attempt to limit your exposure to the allergen that is causing the symptoms. This can mean closing windows, avoiding going outside on days where the pollen count is particularly high, and avoid activities like mowing the lawn. If the method of reduced expose proves futile in reducing the intensity of symptoms, then the use of medication may be applicable. This can include antihistamines, decongestants, and nasal spray steroids. If this still fails to relieve symptoms, then pay a visit to your health care professional, who may refer you to an immunologist or allergist, for courses of immunotherapy, or allergy shots, which can help to desensitize an individual to allergens. 

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