Normal body temperature typically ranges from 97.6 to 99.6 degrees Fahrenheit, though it can vary slightly from person to person. A temperature above this range indicates a fever, one of the body’s natural defenses against infection. Like chills and fatigue, fever is a common symptom of many illnesses and signals that your body is actively working to fight off infection. When bacteria or your immune system release substances called pyrogens, they signal your body to raise its temperature, creating an environment that’s less hospitable to harmful bacteria. This process also boosts the activity of white blood cells, which are essential for fighting off infections.

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