When the influenza virus enters the body, it triggers an inflammatory response. This response leads to the production of a flood of inflammatory chemicals that cause blood vessels to become leaky. The immune system uses these leaky blood vessels to travel to the site of infection and attack the virus, which causes characteristic flu symptoms such as muscle and joint aches.
Inflammation also affects nerves in the body, making them more sensitive to pain. This sensitivity can make muscle and joint aches feel more intense and uncomfortable. The combination of inflammation and increased nerve sensitivity is what makes the flu feel so achy and miserable.
Understanding how inflammation contributes to flu symptoms can help explain why over-the-counter pain relievers, which reduce inflammation, can help alleviate some discomfort. Additionally, this knowledge can inform the development of new treatments for the flu that target the inflammatory response itself.