Can allergies cause a fever? Many people seem to think so; considering the complex chain of events the body goes through after exposure to an allergen it’s a conclusion most people could understandably draw.
The human body is a miniature processing plant, with an internal heat source required to maintain life. The average temperature for this biological engine is 98.6° F. However, this is never a constant, and in children this “average” can fluctuate by several degrees during the course of a single day. The body’s temperature also registers differently dependent upon where the temperature is taken: a thermometer in the mouth is standard, but temperatures taken in the armpit are usually 1° lower than the oral temperature, while temperatures taken rectally are about 1° higher.
The clinical definition of fever is simple: it is a condition in which the temperature is abnormally high and sustained. The guidelines are easily remembered as well: any temperature more than 0.5° above normal as measured on two successive occasions in a two-hour period classifies as a fever.
Those with spring time and summer allergies to pollen, commonly called hay fever, contains the very word “fever” in its name. Do allergies cause fever? Again, the common belief is associative: the allergic reaction sets in, and a fever develops; therefore, allergies can cause fever.
The answer to the question – “can allergies cause fever?” – requires a look at the dynamic behind allergies. Allergies are caused in people with hypersensitivity to certain substances called antigens. Antigens are made of proteins. Exposure to antigens normally triggers the immune response, and antibodies are formed to destroy them.
In those with a hyper-driven metabolic response to these common antigens, known as an allergic response, the body’s immune system kicks into overdrive. It floods the body with antibodies. When these two meet – antibody and antigen – mast cells produce histamine. It is this excess of histamine that creates the conditions of discomfort and misery associated with allergies. And one of the body’s defense mechanisms to foreign invasion is to ramp up the internal heat, killing off the offending organisms. This is fever.
Fevers are a secondary response to the exposure to allergens. For instance, a person suffering from nasal allergies can develop chronic sinusitis. The sinusitis, in turn, can cause a fever to fight the infection. Can allergies cause a fever? The correct answer is “no”. The antigen may spur an allergic reaction, but allergies do not cause fevers. The allergy is the catalyst – the fever is caused by other metabolic processes.