What is l-arginine good for?

Arginine. ....Is something your body normally makes, but you can be deficient if you don't have enough of the building blocks. Symptoms of deficiency include poor wound healing, hair loss, skin rash, constipation, and fatty liver. There is some evidence it may be useful for claudication (pain in your legs with exercise due to poor circulation). It's used for lots of other things, but without good evidence.