Is There An Over The Conter Cream Fir What Looks

Is there an over the conter cream fir what looks like mabe a cold sore on lio or some rype of ring worm on upper lip. Its small round and dark in the middle. My son gad something similar in Nov of last year and was perscribed Ketoconazole 2% cream . I didnt know if that can be applied on the lip.