• Ranitidine reduces the secretion of gastric acid in the stomach by blocking the effect of histamine on histamine H2 receptors located on the parietal cells lining the stomach wall. Histamine is the chemical transmitter that stimulates the parietal cells to release gastric acid. By blocking H2 receptors, ranitidine prevents histamine from having this effect, thereby reducing gastric acid secretion.
• Ranitidine is specific for H2 receptors (other drugs, called antihistamines, block H1 receptors which are primarily involved with allergic-type reactions).
• Ranitidine belongs to a group of drugs known as H2 receptor antagonists (also called H2 blockers).
• Ranitidine was withdrawn from the U.S. market in 2020. This was because a contaminant known as N-Nitrosodimethylamine (NDMA) was found in ranitidine medications. This contaminant increased in concentration over time and when ranitidine was stored at higher than room temperature. NDMA is a probable human carcinogen (a substance that could cause cancer).
• This patient tip is retained for education purposes only.

• Ranitidine was used for the short-term treatment of active duodenal or gastric ulcers.
• Reduced stomach acid secretion so was used for the treatment of gastroesophageal reflux disease (GERD) or hypersecretory conditions such as Zollinger-Ellison syndrome, systemic mastocytosis, and endoscopically diagnosed erosive esophagitis.
• Ranitidine was sold over-the-counter in approved packaging which allowed adults and children older than 12 years to self-medicate for mild gastrointestinal complaints such as occasional heartburn, indigestion, or sour stomach brought on by certain foods.
• Was used in addition to antacids.
• Generic ranitidine was available.

If you are between the ages of 18 and 60, take no other medication or have no other medical conditions, side effects you are more likely to experience include:

• A headache and gastrointestinal side effects (such as constipation, diarrhea, nausea, and abdominal pain) were the most commonly reported side effects. Other side effects were rare.
• May have caused false-positive results on urine protein tests and higher dosages could affect liver function.
• The dosage of ranitidine needed to be adjusted in people with kidney disease, and considered in those with liver disease.
• Not for people with acute porphyria (a group of disorders characterized by the build-up of porphyrin-producing natural chemicals).
• There was a potential for interaction with some other medications including warfarin, HIV antivirals, nifedipine, procainamide, and benzodiazepines.
• Vitamin B12 deficiency could occur with long-term therapy.
• In early 2020, the FDA requested the removal of all ranitidine products from the market. This was because a contaminant known as N-Nitrosodimethylamine (NDMA) was found in ranitidine medications. This contaminant increased in concentration over time and when ranitidine was stored at higher than room temperature. NDMA is a probable human carcinogen (a substance that could cause cancer).
• Only use during pregnancy if the benefits clearly outweigh the harms. Animal studies have failed to reveal evidence of impaired fertility or fetal harm but there are few human studies. It is unknown if there is a link between the use of gastric-suppressing drugs during pregnancy and childhood allergy and asthma. Ranitidine is excreted into human milk but there is no data on adverse effects. It is also known to increase prolactin levels. There is no data on galactorrhea. Caution is recommended.

Note: In general, seniors or children, people with certain medical conditions (such as liver or kidney problems, heart disease, diabetes, seizures) or people who take other medications are more at risk of developing a wider range of side effects. View complete list of side effects

• Do not take ranitidine because of the risk of NDMA contaminants.

• Peak effects are reached two to three hours after taking a 150mg dose. Symptomatic relief of GERD occurs within 24 hours of starting ranitidine therapy.
• One 150mg dose of ranitidine substantially inhibits gastric acid secretion for approximately 9.5 hours.
• Food does not appear to affect the absorption of ranitidine or its peak concentration.

Medicines that interact with ranitidine may either decrease its effect, affect how long it works, increase side effects, or have less of an effect when taken with ranitidine. An interaction between two medications does not always mean that you must stop taking one of the medications; however, sometimes it does. Speak to your doctor about how drug interactions should be managed.

Common medications that may interact with ranitidine include:

• anticoagulants (blood thinners), such as warfarin, or other drugs that have blood thinning effects such as aspirin or NSAIDs
• antifungals, such as fluconazole, itraconazole, ketoconazole, or voriconazole
• cancer treatments, such as bosutinib, dabrafenib, dasatinib, erlotinib, neratinib, or pazopanib
• epilepsy medications, such as carbamazepine, fosphenytoin, phenobarbital, or phenytoin
• fentanyl
• hepatitis medications, such as boceprevir, ledipasvir, sofosbuvir, and telaprevir
• HIV medications (eg, atazanavir, indinavir, ritonavir, or saquinavir)
• iron supplements, such as ferrous fumarate, ferrous gluconate, or ferrous sulfate
• loperamide
• metformin
• multivitamins
• theophylline
• warfarin.

Note that this list is not all-inclusive and includes only common medications that may interact with ranitidine. You should refer to the prescribing information for ranitidine for a complete list of interactions.

Ranitidine is no longer available in the United States.