Urtication is the use of plants to stimulate circulation to the skin. The nettles can be intentionally brushed on arthritic areas to achieve this purpose. But beware - the tingling can go on for hours! Even last night my leg felt like there were little insects crawling on it from this! Fun!
Nettles can be taken for allergies to strengthen the body - but some have slight allergic reactions to them also - so be ware!
As a food: steamed and then served with organic soy sauce [non-GMO] and sesame oil is delicious. They can easily be thrown in any soup or stir fry for added flavour or nutrition. And they're free!