My husband has black powdery liquid diarrhea. no other pain or symptoms. should i be concern does he need to go emergency room?

NOT good if melena: Dark-colored stools may result from iron supplements, foods you eat (like a lot of spinach), substances (like peptobismol), but most significantly suggests bleeding. When blood is denatured by acid in your stomach, as from ulcers, stools will turn tarry ("melena"). Blood may also be ingested from nose bleeds, bleeding gums. Stop any nsaid's he's taking & call his doctor right away for evaluation.