Canadian Actors' Equity Association provides every member working under contract with an Voluntary Emergency Medical Information form. The individual is encouraged to fill out the form with basic info, emergency contact, insurance info, and relevant medical details such as prescription medications, drug allergies, chronic conditions, etc. The form is sealed in an envelope, with a signature across the seal. Forms are held securely by stage management, and are only accessed in the case of a medical emergency where the individual cannot respond to medical personnel (i.e. unconscious). The envelope is returned to the member at the end of the contract.
These forms are voluntary, but I remind artists very clearly about the medical benefit of quick access to this information in an emergency. I store ours in a locked drawer in one of our touring crates - easy to get to when we are at home in rehearsal, and always in the theatre when we are on tour. It takes a bit of planning to ensure the forms are always in the same location as our dancers when smaller groups separate for outreach and educational performances, but it's just a matter of making it a checklist item.