About this whole Excedrin bounceback headache thing. Sure, if you take it every day or multiple times a day you might get a bounceback. But it's probably the caffeine that's causing it.
And if you get relief from Excedrin but not from Tylenol, it's probably the caffeine that is the difference. Because of the vasoconstriction that the caffeine produces. You can get practically the same effect by taking a couple Tylenol with a cup of strong coffee. That's my Go To remedy if I get a migraine and am away from home.
FYI, aceptaminophen on its own is capable of causing medication rebound headaches if taken on more than a certain number of days in a month.
See: http://www.amentheadachecenter.com/headaches/rebound-headaches/
QUOTE: Rebound headaches, also known as Medication–Overuse Headaches, are caused by the near-daily use of a headache medication. Rather than being the solution, the medication becomes part of the problem. A rule of thumb is that if you are taking medication for your headache 10 or more days of the month, the medication may actually be perpetuating, or even causing the problem.
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Rebound headaches can be caused by a number of very common over-the-counter medications, as well as medications frequently prescribed by your physician. The most common over-the-counter medications causing rebound headache include: Tylenol, Excedrin, Excedrin Migraine, NSAIDs (ibuprofen, naproxen, etc.). The most common prescription medications causing rebound headache include: Fioricet, Fiorinal, Vicodin, Percocet, Tylenol with Codeine. Even migraine–specific medications can cause rebound, including: Imitrex, Maxalt, Relpax, and other triptans. In fact, even non-medications can cause rebound – caffeine in excess quantities, for example.
Also see http://www.mayoclinic.org/diseases-conditions/rebound-headaches/basics/causes/con-20024096
SW