He(28years)is taking seroxat & lexotanil from 3 years & the psychiatric said he should continue talking it always.does it have bad impact years later?

Med monitoring: If a prescribing professional says to take a medication indefinitely without regular exams to reassess the need to continue that medication, I would get a second opinion. All medications have side effects, some have long-term side effects. I'm not aware that Seroxat or Lexotanil have long-term side effects but that doesn't mean it's ok or necessary to stay on them for a lifetime.