Gastrointestinal drugs often are used to relieve uncomfortable and potentially dangerous symptoms, rather than as cures for specific diseases. Antacids neutralize the hydrochloric acid in the stomach to relieve symptoms of peptic ulcer, esophagitis, and reflux. Antiulcer drugs block secretion of acid by cells in the lining of the stomach and are prescribed for patients with gastric and duodenal ulcers and gastroesophageal reflux disease (GERD).

Histamine H2 receptor antagonists such as ranitidine (Zantac) and cimetidine (Tagamet) turn off histamine, which promotes secretion of stomach acid. Another drug, omeprazole (Prilosec), works by stopping acid production by a different method (proton pump inhibition).

Antidiarrheal drugs relieve diarrhea and decrease the rapid movement (peristalsis) in the muscular walls of the colon. Cathartics relieve constipation and promote defecation for diagnostic and operative procedures and are used to treat disorders of the gastrointestinal tract. Some cathartics increase the intestinal salt content to cause fluid to fill the intestines; others increase the bulk of the feces to promote peristalsis. Another type of cathartic lubricates the intestinal tract to produce soft stools. Laxatives are mild cathartics, and purgatives are strong cathartics.

Antinauseants (antiemetics) relieve nausea and vomiting and overcome vertigo, dizziness, motion sickness, and similar symptoms due to labyrinthitis (inflammation of the inner ear).

Anti-TNF (tumor necrosis factor) drugs are used to treat autoimmune diseases such as Crohn's. These drugs also are used against rheumatoid arthritis.

The various types of gastrointestinal drugs and examples of each are listed below:


   aluminum and magnesium antacid (Gaviscon)

   magnesium antacid (milk of magnesia)

   aluminum antacid (Rolaids)


   diphenoxylate + atropine (Lomotil)

   loperamide (Imodium)



   metoclopramide (Reglan)

   ondansetron (Zofran)

   promethazine (Phenergan)

   prochlorperazine maleate (Compazine