This chapter aims to cover discussion on drug treatment of diarrhea. Diarrhea treatment includes fluid and electrolyte replacement, specific therapy to treat the cause, and antimotility and antisecretory agents. Viral cause of diarrhea is usually self-limiting, hence no antibiotics are required. Antimotility, antisecretory agents and adsorbents offer only symptomatic relief in noninfective diarrhea. Codeine is a natural opium alkaloid and it stimulates opioid receptors in GI smooth muscles. Diphenoxylate, loperamide, antisecretory agents, octreotide, antispasmodics, clonidine, and probiotics are the other drugs which are used in the treatment of diarrhea. Drug treatment for constipation and drugs causing constipation are also discussed briefly in this chapter.