Shulchan Arukh, Orach Chayim 532/שולחן ערוך·אורח חיים תקל״ב

1Cutting Nails on Chol HaMoed. Containing 2 paragraphs: It is permitted to cut fingernails and toenails, even with scissors. Rema: But there are some who are stringent and forbid this. The practice is to be stringent not to cut them, whether with a knife or scissors, if it is not for the mitzvah of immersion, when they should be cut as they are normally done on a weekday (Sma"k and Tosafot).

2Everything medical is allowed on hol hamoed.