Cimetidine is a stomach acid reducer that is used to treat and prevent certain types of stomach ulcer. Cimetidine is also used to treat gastroesophageal reflux disease (GERD), when stomach acid backs up into the esophagus and causes heartburn.

Over-the-counter (nonprescription) cimetidine is used to treat heartburn with sour stomach and acid indigestion, or to prevent these conditions when caused by certain foods or beverages.

Cimetidine may also be used for purposes not listed in this medication guide.

Follow all directions on your medicine label and package. Tell each of your healthcare providers about all your medical conditions, allergies, and all medicines you use.

Cimetidine comes as a tablet and a liquid to take by mouth. It is usually taken once a day at bedtime or two to four times a day with meals and at bedtime. Over-the-counter cimetidine is usually taken once or twice a day with a glass of water. To prevent symptoms, it is taken within 30 minutes before eating or drinking foods that cause heartburn. Follow the directions on your prescription or the package label carefully, and ask your doctor or pharmacist to explain any part you do not understand. Take cimetidine exactly as directed. Do not take more or less of it or take it more often than prescribed by your doctor.

Do not take over-the-counter cimetidine for longer than 2 weeks unless your doctor tells you to. If symptoms of heartburn, acid indigestion, or sour stomach last longer than 2 weeks, stop taking cimetidine and call your doctor.

Use exactly as directed on the label, or as prescribed by your doctor.

Cimetidine is usually taken with meals or at bedtime.

To prevent heartburn from foods or beverages, take cimetidine within 30 minutes before eating or drinking.

Take this medicine with a full glass of water.

Measure liquid medicine carefully. Use the dosing syringe provided, or use a medicine dose-measuring device (not a kitchen spoon).

It may take up to 8 weeks for an ulcer to heal. Use this medicine for the full prescribed length of time, even if your symptoms quickly improve.

Your ulcer may take longer to heal if you smoke cigarettes.

Call your doctor if your symptoms do not improve, or if they get worse.

Do not take over-the-counter cimetidine for longer than 14 days without your doctor's advice.

Store at room temperature away from moisture, heat, and light.

Heartburn can mimic early symptoms of a heart attack. Get emergency medical help if you have chest pain that spreads to your jaw or shoulder and you feel anxious or light-headed.

You should not use cimetidine if you are allergic to cimetidine or other stomach acid reducers (such as ranitidine, famotidine, Zantac, Axid, and others)

Ask a doctor or pharmacist if cimetidine is safe to use if you have:

• stomach pain, nausea, and vomiting;

• trouble swallowing;

• frequent chest pain;

• heartburn with wheezing;

• unexplained weight loss;

• heartburn lasting longer than 3 months; or

• liver or kidney disease.

Ask a doctor before using this medicine if you are pregnant.

You should not breastfeed while using cimetidine.

Do not give this medicine to a child without medical advice.

Take the medicine as soon as you can, but skip the missed dose if it is almost time for your next dose. Do not take two doses at one time.

Seek emergency medical attention or call the Poison Help line at 1-800-222-1222.

Keep this medication in the container it came in, tightly closed, and out of reach of children. Store it at room temperature and away from excess heat and moisture (not in the bathroom).

Unneeded medications should be disposed of in special ways to ensure that pets, children, and other people cannot consume them. However, you should not flush this medication down the toilet. Instead, the best way to dispose of your medication is through a medicine take-back program. Talk to your pharmacist or contact your local garbage/recycling department to learn about take-back programs in your community. See the FDA's Safe Disposal of Medicines website (http://goo.gl/c4Rm4p) for more information if you do not have access to a take-back program.

It is important to keep all medication out of sight and reach of children as many containers (such as weekly pill minders and those for eye drops, creams, patches, and inhalers) are not child-resistant and young children can open them easily. To protect young children from poisoning, always lock safety caps and immediately place the medication in a safe location – one that is up and away and out of their sight and reach. http://www.upandaway.org

Unless your doctor tells you otherwise, continue your normal diet.

Avoid taking other medications within 2 hours before or 2 hours after you take cimetidine. Cimetidine can make it harder for your body to absorb certain medicines you take by mouth.

Ask your doctor before using other stomach acid reducers or antacids, and use only the type your doctor recommends.

Get emergency medical help if you have signs of an allergic reaction (hives, difficult breathing, swelling in your face or throat) or a severe skin reaction (fever, sore throat, burning in your eyes, skin pain, red or purple skin rash that spreads and causes blistering and peeling).

cimetidine may cause serious side effects. Stop using cimetidine and call your doctor at once if you have:

• pain when swallowing;

• bloody or tarry stools, cough with bloody mucus or vomit that looks like coffee grounds;

• changes in mood, anxiety, agitation;

• confusion, hallucinations; or

• breast swelling or tenderness.

Serious side effects may be more likely in older adults and those who are ill or debilitated.

Common side effects of cimetidine may include:

• headache; or

• diarrhea.

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.

Ask a doctor or pharmacist before using cimetidine with any other medications, especially:

• ketoconazole;

• phenytoin;

• theophylline;

• an antidepressant; or

• a blood thinner--warfarin, Coumadin, Jantoven;

• heart or blood pressure medicine--nifedipine, propranolol; or

• a sedative--chlordiazepoxide, diazepam.

This list is not complete and many other drugs may affect cimetidine, or be made less effective when taken at the same time as cimetidine. This includes prescription and over-the-counter medicines, vitamins, and herbal products. Not all possible drug interactions are listed here.

Keep all appointments with your doctor.

Do not let anyone else take your medicine. Ask your pharmacist any questions you have about refilling your prescription.

It is important for you to keep a written list of all of the prescription and nonprescription (over-the-counter) medicines you are taking, as well as any products such as vitamins, minerals, or other dietary supplements. You should bring this list with you each time you visit a doctor or if you are admitted to a hospital. It is also important information to carry with you in case of emergencies.