Can alcohol damage a retainer?

Usually Not: I'm not sure if your asking whether drinking alcoholic beverages or soaking your retainers in alcohol will damage your retainers. Drinking will not damage the retainer. As for cleaning the retainer, i never recommend using alcohol because isopropyl alcohol is not for consumption. Most of my patients use mouthwash to soak/keep retainers clean (which can contail some alcohol).

Not advisable: We recommend that our patients take their retainers out when they brush their teeth and gently brush their retainers (no toothpaste). We also recommend placing the retainers into denture cleaner every day (follow pkg instructions). Never use alcohol or boiling water.