Generic Name: Cimetidine Brand Name(s): Generics only. No brands available.

Know the basics

What is cimetidine used for?

Cimetidine is used to treat ulcers of the stomach and intestines and prevent them from coming back after they have healed. Cimetidine is also used to treat certain stomach and throat (esophagus) problems caused by too much stomach acid (e.g., Zollinger-Ellison syndrome, erosive esophagitis) or a backward flow of stomach acid into the esophagus (acid reflux disease/GERD). Decreasing extra stomach acid can help relieve symptoms such as stomach pain, heartburn, difficulty swallowing, persistent cough, and trouble sleeping. It can also prevent serious acid damage to your digestive system (e.g., ulcers, cancer of the esophagus).

Cimetidine belongs to a class of drugs commonly called H2 blockers. It works by reducing the amount of acid in your stomach.

Cimetidine is also available without a prescription. It is used to treat occasional heartburn caused by too much acid in the stomach (also called acid indigestion or sour stomach). It is also used to prevent heartburn and acid indigestion caused by certain foods and beverages. If you are taking cimetidine for self-treatment, it is important to read the manufacturer’s package instructions carefully so you know when to consult your doctor or pharmacist. (See also Precautions.)

How should I take cimetidine?

Take cimetidine by mouth with or without food as directed by your doctor.

The dosage and length of treatment are based on your medical condition and response to therapy. Follow your doctor’s instructions carefully. If you are also taking antacids to relieve stomach pain as recommended by your doctor, separate them from this medication by at least 1 hour.

Take cimetidine regularly as prescribed in order to get the most benefit from it. To help you remember, take it at the same time(s) each day. Do not increase your dose or take it more often than directed. Continue to take cimetidine for the prescribed length of treatment even if you are feeling better. Stopping treatment too early may delay the healing process.

If you are using non-prescription cimetidine for self-treatment of acid indigestion or heartburn, take 1 tablet by mouth with a glass of water as needed. To prevent heartburn, take 1 tablet by mouth with a glass of water right before or up to 30 minutes before eating food or drinking beverages that cause heartburn. Do not take more than 2 tablets in 24 hours unless directed by your doctor. Do not take for more than 14 days in a row without talking with your doctor.

Inform your doctor if your symptoms do not improve or if they worsen.

How do I store cimetidine?

Cimetidine is best stored at room temperature away from direct light and moisture. To prevent drug damage, you should not store cimetidine in the bathroom or the freezer. There may be different brands of cimetidine that may have different storage needs. It is important to always check the product package for instructions on storage, or ask your pharmacist. For safety, you should keep all medicines away from children and pets.

You should not flush cimetidine down the toilet or pour them into a drain unless instructed to do so. It is important to properly discard this product when it is expired or no longer needed. Consult your pharmacist for more details about how to safely discard your product.

Know the precautions & warnings

What should I know before using cimetidine?

Use this medication exactly as directed on the label, or as your doctor has prescribed it for you. Do not use more of the medication than recommended. Do not use the medication for longer than recommended.

Avoid taking antacids unless your doctor recommends them for heartburn pain. Follow your doctor’s advice about the type of antacid to use and when to use it. You may not be able to take the antacid at the same time you take your dose of cimetidine.

Is it safe to take cimetidine during pregnancy or breast-feeding?

There are no adequate studies in women for determining risk when using this medication during pregnancy or while breastfeeding. Please always consult with your doctor to weigh the potential benefits and risks before taking this medication. This medication is pregnancy risk category B according to the US Food and Drug Administration (FDA).

FDA pregnancy risk category reference below:

  • A=No risk,
  • B=No risk in some studies,
  • C=There may be some risk,
  • D=Positive evidence of risk,
  • X=Contraindicated,
  • N=Unknown.

Know the side effects

What are the side effects of cimetidine?

Stop using cimetidine and get emergency medical help if you have any of these signs of an allergic reaction: hives; difficulty breathing; swelling of your face, lips, tongue, or throat.

Call your doctor at once if you have any of these serious side effects:

  • Cough, fever, chest congestion, trouble breathing;
  • Red or blistering skin rash;
  • Jaundice (yellowing of the skin or eyes);
  • Easy bruising or bleeding, unusual weakness;
  • Feeling faint, light-headed, disoriented, or confused;
  • Urinating less than usual;
  • Irregular heartbeat; or
  • A rash.

Less serious side effects may include:

  • Feeling dizzy, depressed, or agitated;
  • Breast swelling or tenderness (in men);
  • Joint or muscle pain;
  • Mild skin rash;
  • Headache; or
  • Diarrhea, nausea, or constipation.

Not everyone experiences these side effects. There may be some side effects not listed above. If you have any concerns about a side-effect, please consult your doctor or pharmacist.

Know the interactions

What drugs may interact with cimetidine?

Cimetidine may interact with other drugs that you are currently taking, which can change how your drug works or increase your risk for serious side effects. To avoid any potential drug interactions, you should keep a list of all the drugs you are using (including prescription drugs, non-prescription drugs and herbal products) and share it with your doctor and pharmacist. For your safety, do not start, stop, or change the dosage of any drugs without your doctor’s approval.

Does food or alcohol interact with cimetidine?

Cimetidine may interact with food or alcohol by altering the way the drug works or increase the risk for serious side effects. Please discuss with your doctor or pharmacist any potential food or alcohol interactions before using this drug.

What health conditions may interact with cimetidine?

Cimetidine may interact with your health condition. This interaction may worsen your health condition or alter the way the drug works. It is important to always let your doctor and pharmacist know all the health conditions you currently have, especially:

  • Diabetes;
  • Asthma or a chronic lung disorder;
  • A weak immune system;
  • Bone marrow suppression;
  • Kidney disease; or
  • Liver disease.

Understand the dosage

The information provided is not a substitute for medical advice. ALWAYS consult your doctor or pharmacist before using this medication.

What is the dose of Cimetidine for an adult?

Usual Adult Dose for Duodenal Ulcer:

Parenteral: 300 mg intravenous and intramuscular every 6 to 8 hours. Alternatively, a continuous intravenous infusion may be administered at a rate of 37.5 to 50 mg/hour, or up to a maximum rate of 100 mg/hour (2.4 g/day).

Oral: 800 mg to 1600 mg once a day at bedtime. Alternatively, dosage regimens of 300 mg four times per day, with meals and at bedtime, or 400 mg twice daily, in the morning and at bedtime, have shown to be effective.

Usual Adult Dose for Duodenal Ulcer Prophylaxis:

Parenteral: 300 mg intravenous and intramuscular once or twice a day.

Oral: 400 mg once a day at bedtime.

Usual Adult Dose for Erosive Esophagitis:

Parenteral: 300 mg intravenous and intramuscular every 6 hours. Alternatively, a continuous intravenous infusion may be administered at a rate of 50 mg/hour initially, with 25 mg/hour incremental increases up to a maximum rate of 100 mg/hour (2.4 g/day).

Oral: 800 mg twice a day, or alternatively, 400 mg four times a day.

Usual Adult Dose for Stress Ulcer Prophylaxis:

Parenteral: 300 mg intravenous and intramuscular every 6 hours. Alternatively, a continuous intravenous infusion may be administered at a rate of 50 mg/hour.

Usual Adult Dose for Upper GI Hemorrhage:

Continuous intravenous infusion at a rate of 50 mg/hour preceded by an intravenous bolus dose of 150 mg. Maximum daily dose should not exceed 2.4 g.

Usual Adult Dose for Zollinger-Ellison Syndrome:

Parenteral: 300 mg intravenous and intramuscular every 6 hours. Alternatively, a continuous intravenous infusion may be administered at a rate of 50 mg/hour initially. Infusion rates have ranged from 40 to 600 mg/hour, but should not exceed a daily total of 2.4 g.

Oral: 300 mg 4 times a day with meals and at bedtime.

Usual Adult Dose for Gastric Ulcer:

Parenteral: 300 mg intravenous and intramuscular every 6 hours. Alternatively, a continuous intravenous infusion may be administered at a rate of 50 mg/hour.

Oral: 800 mg once a day at bedtime, or 300 mg 4 times a day.

Usual Adult Dose for Gastroesophageal Reflux Disease:

Parenteral: 300 mg intravenous and intramuscular every 6 hours. Alternatively, a continuous intravenous infusion may be administered at a rate of 50 mg/hour. Maximum daily dose should not exceed 2.4 g.

Oral: 800 mg twice a day, or 400 mg 4 times a day.

Usual Adult Dose for Dyspepsia:

200 mg orally right before (or up to 30 minutes) eating. Maximum per 24 hours: 2 doses.

What is the dose of Cimetidine for a child?

Usual Pediatric Dose for Gastroesophageal Reflux Disease:

Neonatal: 5 to 10 mg/kg/day administered intravenous and intramuscular in divided doses every 8 to 12 hours.

Infants: 10 to 20 mg/kg/day administered intravenous and intramuscular or oral in divided doses every 6 to 12 hours.

Children: 20 to 40 mg/kg/day administered intravenous and intramuscular or oral in divided doses every 6 hours.

Usual Pediatric Dose for Dyspepsia:

Greater than or equal to 12 years: 200 mg up to twice daily; may take 30 minutes prior to eating foods or beverages expected to cause heartburn or indigestion.

How is cimetidine available?

Cimetidine is available in the following dosage forms and strengths:

Tablet 300 mg; 400 mg; 800 mg

What should I do in case of an emergency or overdose?

In case of an emergency or an overdose, call your local emergency services or go to your nearest emergency room.

What should I do if I miss a dose?

If you miss a dose of cimetidine, take it as soon as possible. However, if it is almost time for your next dose, skip the missed dose and take your regular dose as scheduled. Do not take a double dose.

Hello Health Group does not provide medical advice, diagnosis or treatment.

Review Date: January 4, 2017 | Last Modified: January 4, 2017

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