If I had a life threatening allergy I wouldn't keep a notice of it anywhere but on my person.

You guys who keep trying to reinvent the wheel seem to have a tiny problem with reading comprehension, at least 2 people here who work in EMS have written numerous times what we look for and what we don't look for when confronted with an unresponsive patient. EMS providers are not, for the most part, going to change their procedures or their TX protocols because an individual uses what they think is a neat method of medical ID.

If you have a life threatening condition/allergy, use the methods to notify EMS personnel that already work or run the risks of not having your information shared as needed, it's really that simple.