My Father (85 Yrs) With Herpetic Neuralgia Had Been Prescribed

my father (85 yrs) with herpetic neuralgia had been prescribed zeptol 200 (BDPC), progait 75 (OD) and amitryn 10 (OD). but side effects (dizziness mainly) were intense though pain has reduced. he also takes thyronorm 50 and silodal d8. he is taking zeptol 100 and half tablet of progait 75 and amityrn 10 now. side effects have reduced but not disappeared. will it cause him any permanenet damage ?