I recommend Seongsu Yonsei ENT Clinic in Seongsu-dong, Seongdong-gu.

I recommend Seongsu Yonsei ENT Clinic in Seongsu-dong, Seongdong-gu. It's about a minute from Seongsu Station, making it very accessible. The director is friendly, and the atmosphere is pleasant. They're also open on Saturdays, so you can schedule an appointment. Please note the clinic hours posted in front of the clinic. The clinic is located on the second floor.