2. Rebound Headaches: When Analgesic Use Leads to Headaches -- The Cleveland Clinic
While patients sometimes develop chronic daily headaches without ever having headaches before, most patients who develop chronic daily headaches have a history of intermittent headache episodes. Most medical practitioners, and virtually all...
http://www.clevelandclinic.org/health/health-info/docs/0700/0763.asp?index=6170

3. Migraine: Headache: Merck Manual Professional
Analgesics containing opioids, caffeine, or butalbital are helpful for infrequent, mild attacks but are prone to being overused, sometimes leading to rebound headache and daily headache syndrome. For patients who use analgesics frequently,...
http://www.merck.com/mmpe/sec16/ch216/ch216d.html

4. Headache causes and treatment information from iVillage Total Health
Also known as an analgesic rebound headache, this type of headache results from overuse of pain medication. Primary headaches are often a tension headache, migraine or cluster headache. According to the American Council for Headache Education,...
http://yourtotalhealth.ivillage.com/headaches.html?pageNum=3