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Why it's used

Cimetidine is a prescription medicine that is used to treat small intestinal ulcers, non-cancerous stomach ulcers, indigestion, acid reflux, heartburn or stomach pain. It also treats respiratory complication due to inhalation of food, acid or saliva in the lung, viral warts, hives and itching. This medicine works by reducing the amount of acid production in the stomach. Cimetidine is also used to reduce the breakdown of pancreatic enzyme supplements in patients with pancreatic insufficiency and to reduce absorption of food and fluid loss in the short bowel syndrome, for the management of excess acid in the stomach (Zollinger-Ellison syndrome), and to prevent stomach or intestinal bleeding due to stress ulcers in seriously ill patients.
Histamine-2 Receptor Antagonist
Cimetidine belongs to the Histamine-2 Receptor Antagonist class of medicines. Histamine2 receptor antagonists are a class of medications used in the treatment of indigestion, gastric ulcers, and gastroesophageal reflux disease. These medicines decrease the production of stomach acid.

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How to use

Follow directions on the product label, information guide, and provided by your doctor before using Cimetidine. Use this medicine as per your doctor's instructions.
Cimetidine is used with food. To prevent symptoms, take this medicine 30 minutes before eating or drinking that cause heartburn. It is usually taken one or two times a day with a glass of water. Cimetidine is used usually taken in the morning with breakfast and at bedtime.

Typical Dosage

The typical adult dose of Cimetidine is 400 mg twice a day at breakfast and at bedtime (not more than 2400 mg in one day). The typical dose for children is 20-30 mg/kg (9.1-13.6 lb/mg) body weight per day in divided doses. The maximum dose for adults of Cimetidine is 2400 mg/day per day. This medicine is commonly used for a period of 4 weeks for small intestinal (duodenal) ulceration, 6 weeks for non-cancerous (benign) stomach ulcers, 8 weeks for ulcer associated with the continued non steroidal anti-inflammatory drug, and 4-8 weeks for oesophageal reflux disease.
This medicine should be used on an as-needed basis. Cimetidine may be helpful in long-term in patients who may get benefit in reduction of gastric secretion and to prevent relapse in non-cancerous (benign) stomach ulcers.

Talk to Your Doctor

Tell your doctor if your condition does not improve. Talk to your doctor if heartburn, acid indigestion, or sour stomach lasts more than 2 weeks. If you have any kidney disease, In patients with abnormal functioning of the kidneys, the dose of Cimetidine should be reduced. Patients having a creatinine clearance of 0-15 ml/minute, 15-30 ml/minute, and 30-50 ml/minute, should be given a dose of 200 mg twice, thrice and four times a day respectively. A normal dose should be considered to patients with creatinine clearance above 50 ml/minute.
Taking a high dose of this medicine is known to increase the chances of side-effects.

Use in Children

If you are giving Cimetidine to a child, be sure to use a product that is meant for use in children. Before giving this medicine, use the child's weight or age to find the right dose from the leaflet or product package. You can also read the dosage section of this page to know the correct dose for your child. Else, consult with your doctor and follow their recommendation.

Lab Tests

Your doctor may require that certain tests be performed before using Cimetidine. The doctor may ask you to have Endoscopy | Biopsy test. Before starting therapy with Cimetidine in patients with any stomach ulceration, cancer should be excluded by biopsy and endoscopy. Because Cimetidine may relieve the symptoms and help the external healing of stomach cancer.

Storage

Store Cimetidine at 25°C (77°F), and away from moisture. Keep this medicine away from children and pets.
Medicines may be given for uses other than those listed in the medicine guide. Do not use Cimetidine for symptoms for which it was not prescribed. Do not give Cimetidine to others who may have similar symptoms as you. Self-medication can cause harm.

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How to take Cimetidine

Your dose may depend on several personal factors. You should consult with your doctor to find out the dose that is best for you. The dose of Cimetidine depends on the following factors:
  • patient's age
  • patient's weight
  • patient's health
  • the health of the patient's liver
  • medicines recommended by your doctor
  • any other medicines in use
  • herbal supplements consumed
  • response to treatment

Cimetidine Dosage

Dosage for intestinal or non-cancerous stomach ulcers

Adult
  • Recommended: 800 mg/day at bedtime or 200 mg three times a day with meals, or 400 mg at bedtime (1 g/day) and, if inadequate, 400 mg four times a day (1.6 g/day) with meals and at bedtime for 4-6 weeks
  • Maximum: 2400 mg/day (2.4 g/day)
Children (children more than one year old)
  • Recommended: 25-30 mg/kg (11.4-13.6 mg/lb) body weight per day in divided doses
Children (infants under one year old)
  • Recommended: 20 mg/kg (9.09 mg/lb) body weight per day in divided doses

Dosage for gastric secretion or non-cancerous stomach ulcers

Adult (long-term treatment of gastric secretion or active non-cancerous (benign) stomach ulcers to prevent relapse in adults)
  • Recommended: 400 mg at bedtime or 400 mg in the morning and bedtime
  • Maximum: 2400 mg/day (2.4 g/day)

Dosage for backflow of stomach acid to the food pipe

Adult
  • Recommended: 400 mg four times a day, with meals and at bedtime for 4-8 weeks
  • Maximum: 2400 mg/day (2.4 g/day)

Dosage for excess acid in the stomach

Adult
  • Recommended: 400 mg four times a day and the dose may be increased further in occasional cases. If Cimetidine cannot give immediate symptoms relief, antacids can be given to all patients until symptoms disappear
  • Maximum: 2400 mg/day (2.4 g/day)

Dosage for bleeding due to stress ulcers

Adult (stomach or intestinal bleeding due to stress ulcers in seriously ill patients)
  • Recommended: 200-400 mg every 4-6 hours
  • Maximum: 2400 mg/day (2.4 g/day)

Dosage for patients at risk of acid aspiration

Adult (patients at risk of acid aspiration before general anesthesia (Mendelson's syndrome) particularly in obstetric patients during labor)
  • Recommended: 400 mg should be given 90-120 minutes before induction of general anesthesia. If risk persists, dose may be repeated at four hourly intervals
  • Maximum: 2400 mg/day (2.4 g/day)

Dosage for short bowel syndrome

Adult
  • Recommended: 400 mg twice a day
  • Maximum: 2400 mg/day

Dosage for the breakdown of pancreatic enzyme supplements

Adult (the breakdown of pancreatic enzyme supplements in patients with pancreatic insufficiency)
  • Recommended: 800-1600 mg a day according to response, in 4 divided doses, one to one and a half hours before meals
  • Maximum: 2400 mg/day (2.4 g/day)

Dosage calculation for children

To calculate the dosage for children please use the weight based dose calculator to calculate the appropriate dosage as per the weight of your child.

Forms

Tablet
Strength: 100 mg, 200 mg, 300 mg, 400 mg, 600 mg, 800 mg
Tablet, film coated
Strength: 200 mg, 300 mg, 400 mg, 800 mg
injection, solution
Strength: 150 mg/1ml, 6 mg/1ml
Solution
Strength: 300 mg/5ml, 150 mg
Liquid
Strength: 6 mg, 60 mg, 150 mg, 300 mg

Missed Dose

A missed dose should be taken as early as you remember it. However, if the time for the next dose is almost there, then the missed dose should be skipped, and the regular dosing schedule should be continued. Avoid taking a double dose.

Overdose

What to do if you overdose on Cimetidine?
Inducing vomiting or cleaning out of the stomach content (gastric lavage) methods may be used to treat an overdosed person. According to the symptoms, general supportive measures should be performed in case of overdose.
If you think you have overdosed on Cimetidine, call a poison control center immediately. You can look up the poison control center information from the Poison Center Finder at TabletWise.com.

Precautions while using Cimetidine

Before you use Cimetidine, tell your doctor of your medical and health history including the following:
  • abnormality in the functioning of the kidney
  • gastric ulcer
  • immunodeficiency diseases
  • indigestion symptoms
  • liver problems
  • reduced or absent activity of lactase (galactose intolerance and Lapp lactase deficiency) and abnormal absorption of glucose and galactose in the body
  • stomach ulcer
  • taking non-steroidal anti-inflammatory drugs, anticoagulants, phenytoin, theophylline, coumarins, antacids, iron salts, anticonvulsants, bronchodilators, immunosuppressants, medicines that cause a fall in blood cell count, antifungals, antidiabetics, anti-cancer drugs, strong painkillers, antidepressants, antiretroviral drug and tacrolimus
Patients allergic to Cimetidine may experience rash, itching or hives on the skin, swelling of the face or other parts of the body, shortness of breath, wheezing, difficulty in breathing, or life-threatening allergic reaction (anaphylaxis). Using Cimetidine in patients with gastric ulcer and cancer can relieve the symptoms of cancer and may delay the diagnosis of the ulcer.
Before you use Cimetidine, discuss with your doctor if you are allergic to it or its ingredients. Your doctor may prescribe an alternative medicine and update your medical records to record this information.
The use of Cimetidine may change creatinine. Increased levels of creatinine may occur in patients using Cimetidine.
The use of this medicine may change liver enzymes (transaminases). Increased levels of liver enzymes may occur in patients using Cimetidine.

Seizures

Cimetidine may cause rarely seizures in some people. If you perform any activities where a loss of consciousness may cause harm to you (or others), you should discuss with your doctor.

Use in Pregnancy

The use of Cimetidine during pregnancy should only be when required. Cimetidine should not be used during pregnancy unless clearly needed.

Use while Breastfeeding

The use of Cimetidine Cimetidine while breastfeeding should only be when required. Clinical data has shown that Cimetidine may pass into breast milk, which may cause a harmful effect on the children. It should not be used during breastfeeding unless clearly needed.

Use while Conceiving

Consult with your doctor on the use of Cimetidine, if you are trying to conceive.

Side-effects in Older Patients

Cimetidine may cause increased incidence of side-effects in older patients. Elderly patients may see an increased risk of confusion.

Cimetidine Side-effects

The following side-effects may commonly occur when using Cimetidine. If any of these side-effects worsen or last for a long time, you should consult with your doctor:
The following side-effects may commonly occur in older patients on the use of Cimetidine. Discuss with your doctor if any of these side-effects last for a long time or are severe:
Rarely, the use of Cimetidine may cause the following side-effects:
  • excessive or inappropriate production of milk
  • feelings of sadness
  • hair loss
  • infections of the throat
  • joint pain
  • mouth ulcers
  • swelling in between the kidney tubules (interstitial nephritis)
  • swollen male breast tissue
  • trouble getting or keeping an erection (impotence)
The following severe side-effects may also occur when using Cimetidine:
  • stomach or intestinal disorder such as pancreas inflammation
    Symptoms: sudden onset of abdominal pain, nausea vomiting
    If any of these symptoms occur, discontinue the use of Cimetidine.
  • heart disorders
    Symptoms: fast heartbeat, slow heartbeat heart block
    If any of these symptoms occur, discontinue the use of Cimetidine.
  • Symptoms: depression, confusional states hallucinations
    If any of these symptoms occur, discontinue the use of Cimetidine. These symptoms usually disappear within a few days of withdrawing the drug.
  • immune system disorders
    Symptoms: a life-threatening allergic reaction (anaphylaxis)
    If this symptom occurs, discontinue the use of Cimetidine. It usually clears on the withdrawal of the drug.
  • blood disorders such as decrease in the number of leukocytes, abnormally low levels of thrombocytes, body stops producing enough new blood cell, deficiency of red cells, white cells, and platelets (pancytopenia), and lack of granulocytes
    Symptoms: tiredness, shortness of breath, looking pale, frequent infections, bruising nose bleeds
    If any of these symptoms occur, discontinue the use of Cimetidine.
  • liver disorder such as inflammation of the liver (hepatitis)
    Symptoms: increased transaminase levels, nausea, vomiting, loss of appetite, feeling generally unwell, fever, itching, yellowing of the skin and eyes dark coloured urine
    If any of these symptoms occur, discontinue the use of Cimetidine.
  • skin and subcutaneous tissue disorders
    Symptoms: inflammation of the blood vessels caused by allergic reaction
    If this symptom occurs, discontinue the use of Cimetidine. It usually clears on the withdrawal of the drug.
  • kidney disorder
    Symptoms: increases creatinine levels in the blood
  • If this symptom occurs, discontinue the use of Cimetidine.
Your doctor has prescribed this Cimetidine because they have judged that the benefits outweigh the risks posed by side-effects. Many people using this medicine do not have serious side-effects. This is not a complete list of possible side-effects for Cimetidine.
If you experience side-effects or notice other side-effects not listed above, contact your doctor for medical advice. You may also report side-effects to your local food and drug administration authority. You can look up the drug authority contact information from the Drug Authority Finder at TabletWise.com.

Warnings

Abnormal functioning of the kidney

Patients with the abnormal functioning of the kidneys are at an increased risk when using this medicine. Dose reduction should be considered in patients with an abnormality in the functioning of the kidney.

History of stomach ulcer

Patients with a history of stomach ulcer are at an increased risk when using this medicine. Care along with monitoring should be considered in patients using Cimetidine with non-steroidal anti-inflammatory drugs or with a history of stomach ulcer, especially in elderly.

Gastric ulcer and cancer

Patients with gastric ulcer are at an increased risk when using this medicine. Cimetidine may relieve or heal gastric cancer, which may lead to a delay in the diagnosis of the gastric ulcer. This may occur particularly in elderly or middle age patients with new or changed indigestion symptoms. Before starting therapy with Cimetidine in these patients, cancer should be excluded by biopsy and endoscopy.

Patients taking coumarins

Patients taking coumarins are at an increased risk when using this medicine. These patients may experience increased levels of coumarins in the blood. Close monitoring of the blood clotting time should be considered in such patients.

Patients taking phenytoin or theophylline

Patients taking phenytoin or theophylline are at an increased risk when using this medicine. Such patients may experience increased levels of phenytoin or theophylline in the blood. Close monitoring along with dose adjustment should be considered when starting or stopping combination therapy of Cimetidine.

Patients with rare genetic problems

Patients with rare genetic problems of reduced activity or absence of lactase (galactose intolerance and Lapp lactase deficiency) and abnormal absorption of glucose and galactose in the body are at an increased risk when using this medicine. This medicine should not be used in such patients.

Antacids, ketoconazole, digoxin, or iron salts

Cimetidine should be taken at least 2 hours before using these medicines.

Interactions with Cimetidine

When two or more medicines are taken together, it can change how the medicines work and increase the risk of side-effects. In medical terms, this is called as a Drug Interaction.
This page does not contain all the possible interactions of Cimetidine. Share a list of all medicines that you use with your doctor and pharmacist. Do not start, stop, or change the dose of any medicines without the approval of your doctor.

Theophylline

Cimetidine interacts with theophylline, which is used to treat lung disease. When Cimetidine is used with theophylline, it may increase the levels of theophylline in the blood. Clinical monitoring along with dose adjustment of the affected medicine or discontinuation of the therapy should be considered.

Phenytoin

There may be an interaction of Cimetidine with phenytoin, which is used to treat seizures. When Cimetidine is used with phenytoin, it may increase the levels of phenytoin in the blood. Clinical monitoring along with dose adjustment of the affected medicine or discontinuation of the therapy should be considered.

Oral Anticoagulants

Cimetidine may interact with oral anticoagulants (warfarin), which are used to treat heart diseases. Using Cimetidine with warfarin may increase the level of warfarin in the blood. Clinical monitoring along with dose reduction of anticoagulants should be considered in patients using Cimetidine with oral anticoagulants. Also, monitoring of the blood clotting time (prothrombin time) should be considered when using Cimetidine with coumarins.

Tricyclic Antidepressants

Your doctor's guidelines may need to be followed while taking this medicine along with tricyclic antidepressants (amitriptyline), which are used to treat depression. When Cimetidine is used with tricyclic antidepressants, it may increase the levels of these medicines in the blood.

Antiarrhythmics

Special instructions need to be followed while taking this medicine along with antiarrhythmics (lidocaine, procainamide), which are used to treat increased heartbeat. When Cimetidine is used with lidocaine and procainamide, it may increase the levels of antiarrhythmics in the blood. Clinical monitoring along with dose reduction should be considered in patients using Cimetidine with lidocaine.

Immunosuppressants

Your doctor's guidelines may need to be followed while taking this medicine along with immunosuppressants (ciclosporin and tacrolimus), which are used to prevent organ rejection. When Cimetidine is used with ciclosporin or tacrolimus, it may increase the levels of these medicines in the blood.

Metformin

Special instructions need to be followed while taking this medicine along with metformin, which is used to treat high blood sugar. When Cimetidine is used with metformin, it may increase the level of metformin in the blood.

Metoprolol

Cimetidine interacts with metoprolol, which is used to treat high blood pressure. When Cimetidine is used with metoprolol, it may increase the level of metoprolol in the blood.

Oral Sulfonylureas

There may be an interaction of Cimetidine with oral sulfonylureas (glipizide), which is used to treat high blood sugar. When Cimetidine is used with oral sulfonylureas, it may increase the levels of these medicines in the blood.

Calcium Channel Blockers

Cimetidine may interact with calcium channel blockers (diltiazem, nifedipine), which are used to treat high blood pressure. When Cimetidine is used with calcium channel blockers, it may increase the levels of these medicines in the blood.

Anticancer Drugs

Cimetidine interacts with anticancer drugs (fluorouracil, carmustine, or epirubicin), which are used to treat different type of cancer. When Cimetidine is used with anticancer drugs, it may decrease the production of cells (myelosuppressive effects).

Antifungals

There may be an interaction of Cimetidine with antifungals (itraconazole, ketoconazole, or posaconazole), which are used to treat fungal infections of skin, hairs, or nails. When Cimetidine is used with antifungals, it may decrease the absorption of these medicines. Cimetidine should be taken at least two hours before using ketoconazole.

Atazanavir

Cimetidine may interact with atazanavir, which is used to treat human immunodeficiency virus infection. When Cimetidine is used with atazanavir, it may increase the absorption of atazanavir.

Traveling With Medication

  • Ensure that you carry enough doses of each of your prescription medicines to last the entire trip. The best place to store your medicines is in the carry on baggage. However, while flying, if carrying liquid medicines, make sure you do not go over the limits imposed for carry-on liquids.
  • While traveling overseas, make sure that you can carry each of your prescription medicines legally to your destination country. One way to ensure this is by checking with your destination country's embassy or website.
  • Make sure that you carry each of your medicines in their original packaging, which should typically include your name and address, and the details of the prescribing doctor.
  • If your travel involves crossing time zones, and you are required to take your medicine as per a fixed schedule, make sure that you adjust for the change in time.

Expired Medication

Taking a single dose of expired Cimetidine is unlikely to cause a side-effect. However, please discuss with your doctor or pharmacist, if you feel unwell or sick. An expired medicine may become ineffective in treating your prescribed conditions. To be on the safe side, it is important not to use an expired drug. You are much safer by always keeping a fresh supply of unexpired medicines.

Safe Disposal of Medication

  • If there are disposal instructions on the package, please follow the instructions.
  • If there are medicine take-back programs in your country, you should contact the respective authority to arrange for the disposal of the medicine. For example, in the USA, the Drug Enforcement Administration regularly hosts National Prescription Drug Take-Back events.
  • If there are no take-back programs, mix the medicine with dirt and place them in a sealed plastic bag. Throw the plastic bag in your household trash. Separately, remove all personal information including the prescription label from the medicine packaging and then dispose off the container.
  • If specifically indicated on the medicine package that it needs to be flushed down the toilet when no longer needed, perform the required step.

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