My son,35,has migraines,goes through phases of weeks w/3 or 4 a week,& then a pause for weeks w/no headaches,when he is in headache mode,may take 2 excedrin extra strength several days a week,is liver damage an issue? takes no other meds/no drinking?

The number he is taking is not quite clear from the question, but 2 Excedrin a day for several days is not likely to cause liver damage. There are now newer and better medications that could quickly abort the migraine episode, if taken when perceived coming, however it is best to discuss with the doctor so he could be on a medication that would prevent the migraine.

Doubt that liver damage would be an issue, but frequent use of Excedrin could prompt evolution of chronic daily migraines. Far better to utilize migraine abortive, such as triptans, and preventative, either OTC or prescription. A neurologist could surely be beneficial.