During our courses we always tell our participants to check for medic alert tags. There is a growing trend of people getting medic alert tattoos. This could be a fabulous idea, except that there are no standards as to what they should look like. There are those which could easily be mistaken for something else unless they are looked at very closely. Another problem with tattoos is that if an individual 'grows out' of their allergy, they still have the tattoo stating otherwise.
Some people have put the medic alert tattoo on other areas of their body which may or may not be checked by the first-aider. We always check the wrist, so that's the best place for the tattoo.