- What is cimetidine, and how does it work (mechanism of action)?
- What brand names are available for cimetidine?
- Is cimetidine available as a generic drug?
- Do I need a prescription for cimetidine?
- What are the side effects of cimetidine?
- What is the dosage for cimetidine?
- Which drugs or supplements interact with cimetidine?
- Is cimetidine safe to take if I'm pregnant or breastfeeding?
- What else should I know about cimetidine?
What is cimetidine, and how does it work (mechanism of action)?
Cimetidine is a drug that blocks the production of acid by acid-producing cells in the stomach and can be administered orally, IM or IV. It belongs to a class of drugs called H2 (histamine-2) blockers that also includes ranitidine (Zantac), nizatidine (Axid), and famotidine (Pepcid). Histamine is a naturally-occurring chemical that stimulates cells in the stomach (parietal cells) to produce acid. H2-blockers inhibit the action of histamine on the cells, thus reducing the production of acid by the stomach. Since excessive stomach acid can damage the esophagus, stomach, and duodenum by reflux and lead to inflammation and ulceration, reducing stomach acid prevents and allows acid-induced inflammation and ulcers to heal. Cimetidine was approved by the FDA in 1977.
Do I need a prescription for cimetidine?
Yes and OTC (Heart Burn)
What are the side effects of cimetidine?
Side effects due to cimetidine are rare and generally reversible once the medication is stopped. Minor side effects include:
Major side effects include confusion and hallucinations (usually in elderly or critically ill patients), enlargement of the breasts; impotence (usually seen in patients on high doses for prolonged periods); decreased white blood cell counts.
Other side effects include:
Quick GuideHeartburn: Foods to Eat, Foods to Avoid
What is the dosage for cimetidine?
Duodenal ulcers are treated with 800 to 1600 mg at bedtime or 300 mg 4 times a day at meal times and bedtime, or 400 mg twice a day for 4-6 weeks. Maintenance therapy is 400 mg at bedtime.
Active gastric ulcers are treated with 800 mg at bedtime or 300 mg 4 times a day at meal times and bedtime for up to 8 weeks.
The regimen for GERD is 800 mg twice a day or 400 mg 4 times a day for 12 weeks.
Pathological hypersecretory conditions are treated with 300 mg 4 times daily up to 2400 mg daily.
For hospitalized patients who cannot take oral medications, 300 mg of cimetidine may be administered by intravenous or intramuscular injection every 6-8 hours. A continuous intravenous infusion of 37.5 to 50 mg/hour also may be used.
Which drugs or supplements interact with cimetidine?
Cimetidine may increase the blood levels of several drugs by reducing their elimination by the liver. This interaction may occur between cimetidine and warfarin (Coumadin), a commonly used blood thinning agent. Patients taking both medications should have frequent blood monitoring to avoid accumulation of high levels of warfarin leading to excessive blood thinning and bleeding.
Cimetidine also may increase the blood levels phenytoin (Dilantin, Dilantin-125), theophylline (Respbid, Slo-Bid, Theo-24, Theolair), lidocaine, amiodarone (Cordarone), metronidazole (Flagyl), loratadine, calcium channel blockers (for example, diltiazem (Cardizem, Dilacor, Tiazac), felodipine (Plendil), nifedipine (Adalat, Procardia, Afeditab, Nifediac), bupropion (Wellbutrin, Wellbutrin SR, Wellbutrin XL, Zyban, Aplenzin, Forfivo XL), carbamazepine (Tegretol Tegretol XR, Equetro, Carbatrol), and fluvastatin (Lescol, Lescol XL).
Because cimetidine reduces stomach acid, it may reduce the absorption of drugs (for example, ketoconazole [Nizoral, Extina, Xolegel, Kuric]) that are best absorbed in acidic conditions. Such drugs should be administered at least 2 hours before the administration of cimetidine.
Is cimetidine safe to take if I'm pregnant or breastfeeding?
There are no adequate studies of cimetidine in pregnant women.
Cimetidine is excreted in breast milk.
What else should I know about cimetidine?
What preparations of cimetidine are available?
Tablets: 200, 300, 400, and 800 mg. Liquid: 300 mg/5 ml. Injection: 150 mg/ml.
How should I keep cimetidine stored?
Store at room temperature 15 C to 30 C (59 F to 86 F).
Cimetidine (Tagamet) is a drug prescribed for the treatment of GERD, duodenal ulcers, active gastric ulcers, Zollinger Ellison syndrome, heartburn, indigestion; and the prevention of gastrointestinal bleeding. Side effects, drug interactions, dosage, storage, and pregnancy safety information should be reviewed prior to taking this medication.
Multimedia: Slideshows, Images & Quizzes
GERD Quiz: Test Your Digestive Diseases IQ
Who is at risk for developing GERD? Are you? Take this quiz to learn what GERD is, if you're at risk, and what you can do about...
Picture of Gastroesophageal Reflux (GERD)
The stomach contents regurgitate and back up (reflux) into the esophagus The food in the stomach is partially digested by...
Picture of Esophagus
The esophagus is a muscular tube connecting the throat (pharynx) with the stomach. See a picture of the Esophagus and learn more...
Related Disease Conditions
Interstitial Cystitis (IC) and Painful Bladder Syndrome (PBS)
Interstitial cystitis (IC)/painful bladder syndrome (PBS) is an inflammatory disease of the bladder that can cause ulceration and...
GERD (Acid Reflux, Heartburn)
GERD (gastroesophageal reflux disease) is a condition in which the acidified liquid contents of the stomach backs up into the...
Peptic Ulcer (Stomach Ulcer)
Peptic or stomach ulcers are ulcers are an ulcer in the lining of the stomach, duodenum, or esophagus. Ulcer formation is related...
Reflux Laryngitis (Diet, Home Remedies, Medicine)
Reflux laryngitis is caused by acid refluxing back up through the esophagus and voice box. Reflux laryngitis causes irritation...
Scleroderma is an autoimmune disease of the connective tissue. It is characterized by the formation of scar tissue (fibrosis) in...
Hives (Urticaria & Angioedema)
Hives, also called urticaria, is a raised, itchy area of skin that is usually a sign of an allergic reaction. The allergy may be...
Fabry Disease (Symptoms and Life Expectancy)
Fabry disease (Fabry's disease, alpha-galactosidase-A) is a genetic disorder with symptoms such as burning sensations in...
Cough (Chronic, Persistent Cough in Adults and Children)
Chronic cough is a cough that does not go away and is generally a symptom of another disorder such as asthma, allergic...
Barrett's esophagus occurs as a complication of chronic gastroesophageal reflux disease (GERD), primarily in white males. GERD...
Chronic Rhinitis and Post-Nasal Drip (Symptoms, Treatment)
Chronic rhinitis and post-nasal drip symptoms include an itchy, runny nose, sneezing, itchy ears, eyes, and throat. Seasonal...
Hiatal Hernia (Symptoms, Diet, Surgery, Treatment)
Hiatal hernia is a condition in which a thin membrane of tissue connects the esophagus with the diaphragm becomes week, and a...
Medical shock is a life-threatening medical condition. There are several types of medical shock, including: septic shock,...
Molluscum contagiosum is a skin disease that causes pink painless bumps on the skin. It typically resolves in six to 12 months....
Heartburn (Acid Reflux) Symptoms, Relief Medicine, Cures
Heartburn is a burning sensation experienced from acid reflux (GERD). Symptoms of heartburn include chest pain, burning in the...
19 Tips on How to Stop a Cough
Coughing is a reflex that helps a person clear their airways of irritants. There are many causes of an excessive or severe...
Treatment & Diagnosis
- GERD Gastroesophageal Reflux Disease FAQs
- Ulcers May Be Caused By Your Cat
- How To Reduce Your Medication Costs
- Pharmacy Visit, How To Get The Most Out of Your Visit
- Indications for Drugs: Approved vs. Non-approved
- Drugs: Buying Prescription Drugs Online Safely
- Drugs: The Most Common Medication Errors
- Medication Disposal
- Dangers of Mixing Medications
- Generic Drugs, Are They as Good as Brand-Names?
Medications & Supplements
Prevention & Wellness
- Popular Heartburn Drugs May Boost Death Risk: Study
- Clues to How Popular Heartburn Drug Might Harm Arteries
- Common Meds and Dementia: How Strong Is the Link?
- FAQ: Heartburn Meds and Health Risks
- Antihistamines Adding to Drug Pollution in Streams
- FDA Adds More Warnings to Antidepressant's Label
- Infections, Fractures Linked to Acid Reflux Drugs
Report Problems to the Food and Drug Administration
You are encouraged to report negative side effects of prescription drugs to the FDA. Visit the FDA MedWatch website or call 1-800-FDA-1088.
Top cimetidine Related Articles
Barrett's EsophagusBarrett's esophagus occurs as a complication of chronic gastroesophageal reflux disease (GERD), primarily in white males. GERD refers to the reflux of acidic fluid from the stomach into the esophagus (the swallowing tube), and is classically associated with heartburn. Learn the symptoms, causes, and treatments for Barrett's esophagus.
Chronic cough is a cough that does not go away and is generally a symptom of another disorder such as asthma, allergic rhinitis, sinus infection, cigarette smoking, GERD, postnasal drip, bronchitis, pneumonia, medications, and less frequently tumors or other lung disease.
Chronic cough treatment is based on the cause, but may be soothed natural and home remedies.
Esophageal pH MonitoringEsophageal pH monitoring is a procedure for measuring the reflux (regurgitation or backwash) of acid from the stomach into the esophagus. The Esophageal pH test is used to diagnose gastroesophageal reflux disease (GERD) and to determine if the acid is responsible for symptoms such as:
- and sore throat.
Esophagus PictureThe esophagus is a muscular tube connecting the throat (pharynx) with the stomach. See a picture of the Esophagus and learn more about the health topic.
Fabry disease (Fabry's disease, alpha-galactosidase-A) is a genetic disorder with symptoms such as
- burning sensations in the hands,
- small-raised reddish-purplish blemishes on the skin,
- decreases sweating, and
- gastrointestinal (GI) difficulties.
Fabry disease patients are at increased risk of heart attack, heart disease, kidney failure, and stroke. Symptoms of Fabry disease can be treated with medication.
Gastroesophageal Reflux Disease (GERD)GERD (gastroesophageal reflux disease) is a condition in which the acidified liquid contents of the stomach backs up into the esophagus. The symptoms of uncomplicated GERD are:
- regurgitation, and
Take the GERD QuizWho is at risk for developing GERD? Are you? Take this quiz to learn what GERD is, if you're at risk, and what you can do about it.
HivesHives, also called urticaria, is a raised, itchy area of skin that is usually a sign of an allergic reaction. The allergy may be to food or medications, but usually the cause of the allergy (the allergen) is unknown.
Interstitial CystitisInterstitial cystitis (IC)/painful bladder syndrome (PBS) is an inflammatory disease of the bladder that can cause ulceration and bleeding of the bladder's lining and can lead to scarring and stiffening of the bladder. Symptoms of interstitial cystitis may vary among individuals and may even vary with time in the same individual.
Peptic or stomach ulcers are ulcers are an ulcer in the lining of the stomach, duodenum, or esophagus. Ulcer formation is related to H. pylori bacteria in the stomach, use of anti-inflammatory medications, and cigarette smoking. Symptoms of peptic or stomach ulcers include abdominal burning or hunger pain, indigestion, and abdominal discomfort after meals.
Treatment for stomach ulcers depends upon the cause.
Reflux laryngitis is caused by acid refluxing back up through the esophagus and voice box. Reflux laryngitis causes irritation and inflammation of the lining of the esophagus, larynx, and throat; and can lead to symptoms, signs, and other problems like esophagitis, sinusitis, strictures, throat clearing, swallowing problems, asthma, chronic cough, and growths on the vocal cords. Typical symptoms of reflux laryngitis include heartburn, hoarseness, or a sensation of a foreign body in the throat.
Reflux laryngitis can be treated with diet chanes, OTC medication, prescription medication, and lifestyle changes.
SclerodermaScleroderma is an autoimmune disease of the connective tissue. It is characterized by the formation of scar tissue (fibrosis) in the skin and organs of the body, leading to thickness and firmness of involved areas. Scleroderma is also referred to as systemic sclerosis, and the cause is unknown. Treatment of scleroderma is directed toward the individual features that are most troubling to the patient.