yes all opiates lower the seizure threshold, tramadol should not be fucked with in high doses when combining with any other opiate. however, if you've become tolerant to tramadol and can exceed the daily 400mg "limit" without any signs of a seizure then your risk for seizure in conjunction with other opiates will be decreased. obviously this only pertains to people that partake in tramadol consumption, and from my understanding there aren't that many, which is a good thing IMO.