10 Gastrointestinal Medications
Connect common gastrointestinal medications with their drug classes, typical uses, and important cautions across acid-related conditions, nausea, constipation, diarrhea, and other GI disorders.
How to connect drug names and uses
A useful way to learn these medicines is to connect each generic name with its brand name, class, and main use. Brand names can vary by product and country; the examples here are commonly recognized U.S. brands. This guide is for learning medication associations, not for prescribing.
Acid suppression and ulcer protection
include omeprazole (Prilosec), pantoprazole (Protonix), and esomeprazole (Nexium). They are used for GERD, erosive esophagitis, and peptic-ulcer treatment, and suppress gastric acid more strongly than H₂ blockers.
Famotidine (Pepcid) and cimetidine (Tagamet) are histamine-2 (H₂) receptor blockers. They reduce gastric acid and are used for heartburn, GERD, and ulcers; cimetidine has many drug interactions.
include calcium carbonate (Tums) and aluminum/magnesium hydroxide (Maalox, Mylanta). They neutralize acid already present and provide rapid, short-term relief of mild heartburn. Aluminum may cause constipation, while magnesium may cause diarrhea.
(Carafate) is a mucosal protectant that forms a protective barrier over an ulcer; it does not primarily suppress acid. (Cytotec), a prostaglandin analog, helps prevent NSAID-associated gastric ulcers. It can cause diarrhea and uterine contractions, so pregnancy is a major safety concern.
PPIs and H₂ blockers reduce acid through different mechanisms, while neutralize acid that is already present. H. pylori ulcers require combination treatment, typically a PPI plus antibiotics and sometimes bismuth; an acid reducer alone is not the treatment described here.
Medicines for nausea and vomiting
(Zofran) is a 5-HT₃ receptor antagonist used for nausea and vomiting, including with chemotherapy or surgery. It may cause constipation and can prolong the QT interval.
(Reglan) is a dopamine antagonist and prokinetic used for diabetic gastroparesis; it increases upper-GI motility. Its risk of tardive dyskinesia increases with duration of use, so use is generally limited.
Promethazine (Phenergan) is an H₁ antihistamine for nausea and vomiting. Sedation and anticholinergic effects are common concerns. Meclizine (Antivert, Bonine) and dimenhydrinate (Dramamine) are H₁ antihistamines used for motion sickness and vestibular nausea; they may cause drowsiness and dry mouth.
Scopolamine (Transderm Scōp) is an antimuscarinic used to prevent motion-related or postoperative nausea. It can cause dry mouth, blurred vision, and urinary retention. Match the drug to the cause: scopolamine is associated with motion sickness, while is used for gastroparesis.
Laxatives and their mechanisms
Different laxative classes work in different ways. such as psyllium (Metamucil) treats constipation by adding bulk; take it with plenty of fluid. draw water into the stool or bowel: polyethylene glycol 3350 (MiraLAX) is used for constipation, and lactulose (Enulose, Kristalose) is used for constipation and also to lower ammonia in hepatic encephalopathy.
Senna (Senokot) and bisacodyl (Dulcolax) are stimulant laxatives that stimulate bowel activity for short-term constipation relief. Stimulants are commonly reserved for short-term use or when other measures have not worked. Docusate (Colace) is a stool softener that helps soften stool when straining should be avoided, often when hard stool is the concern.
Magnesium hydroxide (Milk of Magnesia) is a saline osmotic laxative used for occasional constipation; use caution in kidney disease. In brief, fiber adds bulk, osmotic agents draw water into the bowel, stimulants increase intestinal activity, and stool softeners help water mix into stool.
Antidiarrheals and warning signs
(Imodium) is a peripheral opioid-receptor agonist and antimotility agent used for symptomatic relief of uncomplicated diarrhea; it slows intestinal movement. Avoid it with bloody or black stool, high fever, or suspected invasive infection unless directed by a clinician. Excessive doses can cause serious cardiac effects.
(Pepto-Bismol) is an antisecretory, salicylate-containing option for mild diarrhea, including traveler’s diarrhea, and upset stomach. It may darken the tongue or stool. Avoid it with salicylate allergy and heed warnings for children and teenagers with viral illness.
Diphenoxylate/atropine (Lomotil) is a prescription opioid antimotility agent combined with an anticholinergic. It may cause sedation and anticholinergic effects, and should be avoided in certain infectious diarrheas, including C. difficile.
Replacing fluids and electrolytes is central to diarrhea care. Diarrhea should not be suppressed indiscriminately: blood in the stool, fever, dehydration, or severe abdominal symptoms warrant medical assessment.
Other common gastrointestinal disorders
Linaclotide (Linzess), lubiprostone (Amitiza), and plecanatide (Trulance) are secretagogues and prescription options for chronic constipation; selected drugs in this group are also used for IBS with constipation (IBS-C). Diarrhea is an important adverse effect.
Rifaximin (Xifaxan) is one prescription option for IBS with diarrhea (IBS-D) and is also used for selected other conditions. For IBS, medication selection depends on the predominant symptom: constipation, diarrhea, or pain.
(Lialda, Asacol, among others) is a 5-aminosalicylate anti-inflammatory used for mild-to-moderate ulcerative colitis and is available in oral and rectal formulations. Inflammatory bowel disease is treated with medicines that control intestinal inflammation, not simply with antidiarrheals.
(Creon, Zenpep) is pancreatic enzyme replacement for exocrine pancreatic insufficiency. It is taken with meals and snacks to aid digestion.
High-yield medication associations
For GERD and ulcers, PPIs commonly end in -prazole; famotidine is an H₂ blocker. act quickly, while PPIs provide stronger acid suppression. For nausea, associate with QT prolongation, with tardive dyskinesia risk, and sedating antihistamines with drowsiness.
For constipation, psyllium is bulk-forming; polyethylene glycol and lactulose are osmotic; senna and bisacodyl are stimulants; and docusate is a stool softener. For diarrhea, slows motility, while is a salicylate-containing option. Check for warning signs before using antimotility drugs.
IBS medicines target symptoms, whereas treats intestinal inflammation in ulcerative colitis.