A headache is a pretty vague complaint, which is a common symptom of a lot of different conditions. A headache alone does not necessarily means you have the flu. But if your head is pounding and you have any other flu-like symptoms, you might be infected. Headaches can occur with the flu for a few reasons. For instance, a headache can be due to increased sinus pressure from inflamed mucous membranes in the sinuses. In addition, if you have not been taking in enough fluids, dehydration can also head to a headache. Headaches from the flu tend to be generalized and severe enough to make you take notice. Over the counter pain medications, a warm or cold compress and fluids may be your best bet when it comes to reducing a headache due to the flu.