Plantain is a common widespread herb, and is considered a noxious weed by many, but like dandelion, has many tried and true health benefits. It is a demulcent, and one of it's more popular uses today is to treat and soothe the respiratory passages of those who suffer from chronic bronchitis. It is also an alterative, or blood cleanser. Imbibed as a tea, it can soothe irritable bowels and help tame flatulence.
More traditionally, it is a common "go to" for bee stings, as it is a drawing agent when used as a spit salve. Spit, because saliva contains antibodies, but if you have an aversion to this, you can also grind the leaf with a small amount of distilled water and apply as a poultice and it will still do its job. It is effective in this manner for bug bites, and splinters of all sorts as well as drawing out infection.
It has bacteriostatic and bactericidal activity when used as cold extraction or infusion.