When the influenza virus enters the body, it triggers an immune response that results in inflammation. This inflammatory reaction causes blood vessels to become leaky, allowing immune cells to travel to the site of infection and attack the virus. As a result, individuals may experience muscle and joint aches, which are characteristic flu symptoms.

Inflammation can also affect the nerves in the body, causing them to become more sensitive to pain. This increased nerve sensitivity can intensify the muscle and joint aches associated with the flu, making them feel even more 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 that reduce inflammation can alleviate some of the discomfort. Furthermore, this knowledge can inform the development of new treatments for the flu that specifically target the inflammatory response itself.