A fever is a sign that occurs when you have a higher-than-normal body temperature and usually indicates that your body is fighting off some type of infection.5 For most adults, a fever is signaled by your body temperature of 100.4F (38 C) or higher.5 For kids, a fever can run anywhere from 99.5°F or higher, depending on where the temperature is measured. Additional fever symptoms may include2: Sweating Chills Shivering Headache Muscle aches Loss of appetite Dehydration General weakness One important thing to note is that a person’s body temperature can fluctuate throughout the day, varying with normal activities or even from things like stress, heavy clothing, certain medications, a menstrual cycle, and exercise.5 If you have experienced any of these things throughout your day and aren’t feeling any other symptoms, then you may not be experiencing a fever.5