17 Common Signs And Symptoms Of Influenza

9. Muscle Pain

Body aches and muscle pain is another common sign that someone is infected with the influenza virus. This is because the body’s immune system is working double time at fighting this contagious disease. The immune system actually releases substances called interleukins, which are ‘compounds that kill foreign invaders that cause disease in the body, such as viruses.’ It’s these interleukins that actually make the joints and muscles swell, causing aches and pains when a person moves around. This is another reason why people feel more exhausted when they’re sick, because the body is working twice as hard to fight and stave off unwanted infections, viruses and bacteria.