Good evening & Welcome to HCM. Incomplete data like age, gender, any associated medical problem like diabetes, duration of anti-fungal (Terbinafine) treatment?? To be effective, Terbinafine should be taken for 6 to 12 weeks. The result of successful treatment will be seen until the nail grows back completely. It may take 4 months or longer to eliminate an infection. If you did not notice any response even after 4 months, it may be due to ineffective treatment or resistance to Terbinafine. In that case other medications like Itraconazole tablet or anti-fungal nail polish containing Ciclopirox would be more effective. Besides, your nail should be trimmed properly this helps reduce pain by reducing pressure and the drug can reach deeper layers of the nail. Any underlying cause like diabetes should be controlled with the medications. Hope the suggestions given would be useful.