Can dranking too much mallox are malanta are any antiacid cause black stool?

Melena--get checked!: Black 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"). Unless you ingested blood from nose bleeds, bleeding gums, then you may have a signficant stomach source of hemorrhage. Get checked now!