Why your whole body aches when you’re sick

Q. I recently had the flu and was struck by how achy I felt. Why does the flu act that way?

A. It’s all about the inflammation that influenza triggers in the body. Flu symptoms run the gamut from fever, sore throat, and headache to fatigue and weakness, but muscle and joint aches are at the heart of the misery — and they’re caused by inflammation.

How? Like any infection, the flu jolts the immune system to fight off invading germs. While that happens, white blood cells travel throughout the body, producing antibodies to attack the virus. This combat generates inflammation, leading you to feel sick and — ironically — serving as proof your body is fighting off the infection.

Time and rest will help you as you recover. But you can also ease aches from the flu by staying hydrated with plenty of water, broth, and other liquids; taking warm showers; and using over-the-counter NSAIDs (nonsteroidal anti-inflammatory drugs) such as ibuprofen (Advil, Motrin) or naproxen (Aleve). Getting the flu vaccine is another way to reduce flu aches, because people who get the virus despite immunization typically have milder cases than unvaccinated people.