I wear a stainless dog tag I had made at a local surplus/outdoors store. Have been wearing such a tag for probably 20 years now. (had to get a new one when my area code changed)

Have on it: name, SSN, home phone # and NO DRUG ALLERGY.

The clinic couldn't trust your blood typing info.

I figure the SSN and phone is sufficient to find everything else responders might need.(including hospital records for relevent medical stuff???)