The gastrointestinal system plays a fundamental role in digestion, nutrient absorption, and maintaining overall human health. Disorders affecting the gastrointestinal tract are among the most common medical conditions worldwide and significantly impact quality of life. Various pharmacological agents are used to prevent, manage, and treat diseases of the gastrointestinal system by targeting specific physiological and pathological mechanisms. These agents include antacids, proton pump inhibitors, H2-receptor antagonists, antiemetics, laxatives, antidiarrheal drugs, and medications used for inflammatory bowel diseases. This article reviews the major classes of drugs affecting the gastrointestinal system, their mechanisms of action, therapeutic applications, and clinical importance in modern medicine. Understanding the pharmacological effects of these agents is essential for improving treatment outcomes and minimizing adverse effects.