As soon as the flu virus invades the body, it activates the immune system to release a cascade of inflammatory chemicals. These substances trigger blood vessels to leak, allowing immune cells to rush to the infection site and combat the virus. This process results in the characteristic symptoms of flu, such as muscle and joint pain.
However, inflammation also has an impact on nerve function in the body. It increases their sensitivity to pain, which intensifies discomfort caused by muscle and joint pain. The combination of inflammation and heightened nerve sensitivity is what makes flu so uncomfortable and miserable for sufferers.
Gaining a better understanding of how inflammation contributes to flu symptoms could help explain why over-the-counter pain relievers that reduce inflammation may provide some relief. Additionally, this knowledge could inform the development of new treatments for influenza that specifically target the inflammatory response itself.