Ranitidine belongs to the class of medications called H2-antagonists. It works by reducing the amount of acid secreted by the stomach in order to reduce ulcer and heartburn pain or to assist in healing of ulcers.

Ranitidine is used to treat and prevent stomach ulcers caused by non-steroidal anti-inflammatory drugs (NSAIDs); to prevent bleeding caused by stress ulcers for very ill people; to prevent a second episode of bleeding in the digestive tract caused by bleeding ulcers; and to prevent inhalation of stomach acid during surgery, for people who are considered at risk of this complication.

It is used to treat stomach and duodenal (intestinal) ulcers, and prevent them from recurring. It is also used to treat gastroesophageal reflux disease (GERD) and Zollinger-Ellison Syndrome.

This medication may be available under multiple brand names and/or in several different forms. Any specific brand name of this medication may not be available in all of the forms or approved for all of the conditions discussed here. As well, some forms of this medication may not be used for all of the conditions discussed here.

Your doctor may have suggested this medication for conditions other than those listed in these drug information articles. If you have not discussed this with your doctor or are not sure why you are taking this medication, speak to your doctor. Do not stop taking this medication without consulting your doctor.

Do not give this medication to anyone else, even if they have the same symptoms as you do. It can be harmful for people to take this medication if their doctor has not prescribed it.

The recommended adult dose of ranitidine ranges from 150 mg daily to 150 mg twice daily or 300 mg once daily depending on the condition being treated. Ranitidine may be taken with or without food.

When used over-the-counter to treat acid indigestion, heartburn, or sour or upset stomach, the usual dose for adults and children 16 years of age or older is 75 mg to 150 mg taken when symptoms appear. If symptoms persist for more than 1 hour or return after 1 hour, you may take a second dose of the same strength. To prevent symptoms brought on by consuming food or beverages, take the dose 30 to 60 minutes before eating food or drinking beverages that are expected to cause symptoms. The maximum dose is 300 mg every 24 hours. Do not take it in this manner for more than 2 weeks without seeking medical advice.

Injection: The injectable form of ranitidine may be used in hospitals under specific circumstances when the patient is not able to swallow tablets. The usual dose of ranitidine injection is 50 mg every 6 to 8 hours given intravenously (into a vein) or intramuscularly (into a muscle).

If you are using the oral liquid form of ranitidine, use an oral syringe to measure each dose of the liquid, as it gives a more accurate measurement than household teaspoons.

Many things can affect the dose of medication that a person needs, such as body weight, other medical conditions, and other medications. If your doctor has recommended a dose different from the ones listed here, do not change the way that you are taking the medication without consulting your doctor.

It is important to take this medication exactly as prescribed by your doctor. If you miss a dose, take it as soon as possible and continue with your regular schedule. If it is almost time for your next dose, skip the missed dose and continue with your regular dosing schedule. Do not take a double dose to make up for a missed one. If you are not sure what to do after missing a dose, contact your doctor or pharmacist for advice.

Store the tablets at room temperature, protect them from light and moisture, and keep them out of the reach of children.

The injection may be stored at room temperature or in the refrigerator between 2°C and 25°C. Protect it from light, and do not allow it to freeze. Keep it out of the reach of children.

Do not take this medication if you are:

• allergic to ranitidine or any ingredients of the medication

Many medications can cause side effects. A side effect is an unwanted response to a medication when it is taken in normal doses. Side effects can be mild or severe, temporary or permanent.

The side effects listed below are not experienced by everyone who takes this medication. If you are concerned about side effects, discuss the risks and benefits of this medication with your doctor.

The following side effects have been reported by at least 1% of people taking this medication. Many of these side effects can be managed, and some may go away on their own over time.

Contact your doctor if you experience these side effects and they are severe or bothersome. Your pharmacist may be able to advise you on managing side effects.

• constipation
• diarrhea
• dizziness
• drowsiness
• headache
• muscle or joint pain
• nausea
• trouble sleeping
• vomiting

Although most of these side effects listed below don't happen very often, they could lead to serious problems if you do not seek medical attention.

Check with your doctor as soon as possible if any of the following side effects occur:

• blurred vision
• breast development (males)
• change of heartbeat (faster, slower, or irregular)
• confusion
• decreased sexual ability
• general feeling of being unwell
• hair loss
• hallucination (hearing or seeing things that aren't there)
• increased frequency of infections
• signs of clotting problems (e.g., unusual nosebleeds, bruising, blood in urine, coughing blood, bleeding gums, cuts that don't stop bleeding)
• signs of depression (e.g., poor concentration, changes in weight, changes in sleep, decreased interest in activities, thoughts of suicide)
• signs of kidney problems (e.g., increased urination at night, decreased urine production, blood in the urine)
• signs of liver problems (e.g., nausea, vomiting, diarrhea, loss of appetite, weight loss, yellowing of the skin or whites of the eyes, dark urine, pale stools)
• skin rash or hives
• stomach pain
• uncontrolled movements
• unusual feelings of excitement

Stop taking the medication and seek immediate medical attention if any of the following occur:

• signs of pancreatitis (e.g., abdominal pain on the upper left side, back pain, nausea, fever, chills, rapid heartbeat, swollen abdomen)
• signs of a serious allergic reaction (e.g., abdominal cramps, difficulty breathing, nausea and vomiting, or swelling of the face and throat)
• signs of a severe skin reaction such as blistering, peeling, a rash covering a large area of the body, a rash that spreads quickly, or a rash combined with fever or discomfort

Some people may experience side effects other than those listed. Check with your doctor if you notice any symptom that worries you while you are taking this medication.

Before you begin using a medication, be sure to inform your doctor of any medical conditions or allergies you may have, any medications you are taking, whether you are pregnant or breast-feeding, and any other significant facts about your health. These factors may affect how you should use this medication.

Kidney function: Kidney disease or reduced kidney function may cause this medication to build up in the body, causing side effects. If you have reduced kidney function or kidney disease, discuss with your doctor how this medication may affect your medical condition, how your medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed.

Pneumonia: People with lung disease, a weak immune system, or diabetes may be at an increased risk of developing pneumonia while taking ranitidine. If you have any of these conditions, discuss with your doctor how this medication may affect your medical condition, how your medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed.

Porphyria: Ranitidine may cause attacks of a condition called acute porphyria (a disorder that affects the production of heme in the body). People with a history of acute porphyria should not take ranitidine.

Stomach cancer: Using medications such as ranitidine may prevent symptoms of stomach cancer from being noticed. If you have recurrent vomiting, difficulty swallowing, blood in the stool, significant unintentional weight loss, fatigue (anemia), or are coughing up blood, check with your doctor right away. If you have heartburn that worsens or returns after using this medication continuously for 2 weeks, check with your doctor.

Use with NSAIDs: If you are also taking non-steroidal anti-inflammatory drugs (NSAIDs; e.g., diclofenac, ibuprofen, naproxen), your doctor should closely monitor your condition, especially if you are a senior or have a history of ulcers.

Pregnancy: This medication should not be used during pregnancy unless the benefits outweigh the risks. If you become pregnant while taking this medication, contact your doctor immediately.

Breast-feeding: This medication passes into breast milk. If you are a breast-feeding and taking ranitidine, it may affect your baby. Talk to your doctor about whether you should continue breast-feeding.

Children: The safety and effectiveness of using this medication have not been established for children less than 8 years of age. Children between the ages of 8 years and 16 years of age, should only use this medication under the supervision of a doctor.

Seniors: Seniors may be more likely to experience interactions with other medications when taking ranitidine. If you are a senior, your doctor should closely monitor your condition.

There may be an interaction between ranitidine and any of the following:

• antacids (e.g., magnesium hydroxide, calcium carbonate; within 2 hours of taking ranitidine)
• atazanavir
• "azole" antifungals (e.g., itraconazole, ketoconazole, posaconazole)
• cefpodoxime
• cefuroxime
• cyclosporine
• fosamprenavir
• glyburide
• ledipasvir
• lomitapide
• lumacaftor and ivacaftor
• multivitamin/mineral supplements
• octreotide
• protein kinase inhibitors (e.g., bosutinib, dasatinib, nilotinib, pazopanib)
• rilpivirine
• risedronate
• secretin
• sotorasib
• triazolam
• velpatasvir
• warfarin

If you are taking any of these medications, speak with your doctor or pharmacist. Depending on your specific circumstances, your doctor may want you to:

• stop taking one of the medications,
• change one of the medications to another,
• change how you are taking one or both of the medications, or
• leave everything as is.

An interaction between two medications does not always mean that you must stop taking one of them. Speak to your doctor about how any drug interactions are being managed or should be managed.

Medications other than those listed above may interact with this medication. Tell your doctor or prescriber about all prescription, over-the-counter (non-prescription), and herbal medications you are taking. Also tell them about any supplements you take. Since caffeine, alcohol, the nicotine from cigarettes, or street drugs can affect the action of many medications, you should let your prescriber know if you use them.