Para obtener un justificante médico IMSS editable en PDF, puedes seguir los siguientes pasos:
El médico debe evaluarte físicamente.
However, there an official digital process that generates a PDF. This PDF is technically "editable" only in the sense that you can fill in your personal details (name, CURP, NSS) before downloading it, but the medical data (diagnosis, days of rest) is entered by the IMSS doctor.
However, if you are a doctor or a medical administrator looking for a to issue a valid medical excuse, or if you need to know how to obtain an official one, I can provide information on the standard formats used by the IMSS (Instituto Mexicano del Seguro Social) and safe alternatives for editing authorized PDFs.
: Platforms like Edit.org allow healthcare professionals to create custom medical notes from scratch.