What causes headache with the flu?

Headaches with the flu are thought to be caused by a combination of factors related to the body's immune response and inflammation:

Inflammation: When you have the flu, your body produces substances called cytokines to help fight off the virus. These cytokines can trigger inflammation in the body, leading to discomfort, pain, and headaches.

Increased nasal congestion: Nasal congestion and sinus inflammation can put pressure on the surrounding tissues and nerves, causing headache pain.

Dehydration: Flu often leads to decreased fluid intake and potential dehydration. Dehydration can cause headaches, especially when accompanied by other symptoms like fever and vomiting.

Fever: High fever itself can contribute to headache development.

Muscle aches: The widespread muscle pain and aches associated with the flu can also involve the muscles around the head and contribute to headache pain.

Secondary infections: In some cases, the flu may lead to secondary bacterial infections in the sinuses or ears. These infections can cause localized inflammation and contribute to headache pain.

Overall, the headache with the flu is thought to be a result of the body's inflammatory response, nasal congestion, potential dehydration, fever, and involvement of muscles around the head.