If you use pain medications to treat headaches more than a couple times a week, a vicious circle can start. Your body can become used to the pain medication, making it less effective. That reduces the pain threshold, which is your body's ability to tolerate pain. The result is that headaches occur more frequently and more easily. You then use more pain medication on a more frequent basis in an effort to prevent and treat your headaches. These rebound headaches eventually evolve into chronic daily headaches that do not respond to treatment.