What Are the Common Causes of a Fever?

According to the WHO, seasonal influenza kills up to 650,000 people annually. Emerging infectious diseases around the world threaten public health on an unprecedented scale.

Usually, a fever is just a sign that your immune system is working hard to fight off an infection. However, there are specific causes of a fever that require medical attention. A seemingly harmless fever could be hiding something more severe.

In this article, we’ll be going over some common causes of a fever. Read on to learn more.

Causes of a Fever: Viral Infections

Viral infections include the flu, respiratory syncytial virus (RSV), and rhinoviruses (common causes of the common cold). Other less common causes include hepatitis A and HIV.

A fever is generally caused by the body’s immune system fighting off an infection. While most fevers are not dangerous, some can indicate more severe diseases. The higher temperature helps to kill the virus.

Check here for more info on what you should know about the flu.

Side Effects of Medication

Medications that can cause fevers include antibiotics, anticancer drugs, and NSAIDs. In some cases, a fever may indicate an underlying medical condition, such as an autoimmune disease. Sometimes, a person may also experience a fever after taking a vaccine if you are feeling drowsy and has a fever after starting a new medication.

If you have a fever accompanied by other symptoms, such as a rash or shortness of breath, you must see a doctor to rule out a more severe condition.

Overstimulation of the Immune System

A fever can occur when the body is fighting off an infection or other illness or is exposed to a new stressor, such as a vaccine. The immune system releases various chemicals that can cause feverish symptoms in response to these threats.

In some cases, the types of fevers may be a beneficial response that helps the body fight off the infection. However, in other cases, the fever may signify that the body is struggling to cope with the stressor; if a fever persists for several days or becomes very high, consult your doctor.

Exposure to Extreme Temperatures

Exposure can include spending too much time in the sun or a humid environment or, conversely, being in a freezing place for too long. Either way, the body’s internal temperature regulation system gets thrown off, leading to a fever. In most cases, this is nothing to be too concerned about and will eventually resolve on its own.


Inflammation is the body’s response to an infection or injury, and it can cause swelling, redness, and warmth. A fever is the body’s way of increasing its temperature to fight off the infection or injury, so if you have a fever likely because your body is fighting off a sickness or healing from an injury.

Seeking Medical Attention

If you have a fever, it is essential to seek medical attention to find the cause—many common causes of a fever, such as infection, inflammation, and autoimmune disorders. Proper diagnosis and treatment can resolve most fevers quickly and without complications.

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