My 14 year old brother's tongue is badly covered with black patches. the back of his mouth is covered as well. is he ok ?

Black hairy tongue: Black hairy tongue is a harmless, temporary condition that gives the tongue a dark, furry look, related to a build up of dead skin cells on the surface of the tongue. These get stained by food dyes, medication containing bismuth, such as Pepto Bismol, (bismuth subsalicylate) tobacco, as well as bacteria or viruses. If feeling ill, see a doctor, otherwise, gentle brushing of the tongue will help.