Hi there, Excedrin Migraine contains acetaminophen as well, so I would not stack the two of it together. Wait at least 4-6 hours before you take the Excedrin so that you don t end up with an overdose of acetaminophen. You could just continue with the Excedrin after that, since there is enough aspirin inside to help with the foot as well. If you do wish to know the calculation for future use, the standard dose of acetaminophen is usually 1000 mg every 6 hours or so, not more than 4 doses in a day. You need to check the dose of acetaminophen in your oxycodone-acetaminophen tablets, and add it to the Excedrin. The usual dose in two tablets of Excedrin Migraine would be 500 mg, so you actually have a little bit of leeway before you take too much. Having said that, I personally do not like using big combinations in medication, because it restricts your flexibility when choosing the combination. If you find that the caffeine in Excedrin works well for you, choose a simpler combination like caffeine/ergotamine. That way, it frees you to use acetaminophen and the anti-inflammatory group (like aspirin or diclofenac) for other purposes like fever or injuries, without worrying about lack of options or overdosage when a migraine strikes. Hope this helps, and all the best to you. Regards, Dr. Teh