Why do you feel sick when you have a virus?

When you have a virus, your body activates the immune system to fight off the infection, which can lead to inflammation and the release of chemicals called cytokines. These cytokines can trigger symptoms like fever, fatigue, and body aches as part of the immune response. Additionally, the virus itself may disrupt normal bodily functions, contributing to feelings of sickness. Together, these factors result in the overall sensation of being unwell.