When you have a fever, your body temperature is higher than 37.4°C . Don’t rely on touch to assess a temperature. Use a thermometer. As a child , you may also experience: Irritability Lethargy Longer sleeping time Febrile fits during a sudden rise in temperature, or before a fever is detected. Reduced appetite for food and drinks Shivers As an adult , you may also experience: Headaches Body aches Hot, flushed face Loss of appetite Sweating or weakness Shivers