Most people don't know what certification numbers mean. The industry counts on that confusion.
Drug number (国药准字) — real medicine, gone through clinical trials. Health food number (卫健食字) — supplements that CANNOT claim to treat disease. Medical device number (械字) — bandages, thermometers, etc. Disinfection number (卫消证字) — hand sanitizer, surface cleaners. It kills germs but does NOT treat medical conditions.
Watch out for: disinfection products sold as ointments, health food claiming to cure diseases, products with no certification at all. Flip the package over. Read the number. A few seconds of reading could save you hundreds of yuan.