The body aches experienced when sick are primarily caused by the body's immune response to infection. When the immune system detects an invader such as a virus, it activates white blood cells that produce antibodies to fight the infection. This immune response leads to inflammation throughout the body, particularly in muscles and joints, which causes pain and discomfort. Cytokines, small proteins released during this process, also contribute to inflammation and muscle ache. The aches serve as a sign that the body is actively combating the illness. Additionally, symptoms like fever, fatigue, and dehydration during sickness can exacerbate muscle soreness and weakness.
In summary, body aches during sickness are a result of inflammation caused by the immune system's efforts to fight the infection, alongside factors like fever and dehydration that further stress muscles and joints.
