With all due respect, dock leaves are not a myth. However, they have to be applied in the right fashion. Crucial is the fact that it is the SAP within the leaves that contains antihistamines. This means that just rubbing them on your arms/legs/knackers ain’t going to work.
You need to take two or three leaves and crush them by rolling them vigorously in your hands. Keep going until your hands are pretty much coated in light green sap. Apply the sap to the effected area. Works a treat. I’ve been doing it for years and recently applied it to my 2.5 yr old who’d fallen into a patch of young nettles (most vicious) in shorts and t-shirt.
You’ll still get the tingle later on, but it won’t hurt half as much.