Famotidine (Acid Controller Maximum Strength)

1. Health Canada Product Monograph — Famotidine

• Used to treat heartburn, acid indigestion, and sour or upset stomach caused by excess stomach acid.
• Used to prevent heartburn, acid indigestion, and sour or upset stomach, including nighttime symptoms, when taken before eating or drinking something expected to cause symptoms.

• Animal studies in rats and rabbits at doses far exceeding the human dose showed no evidence of harm to the fetus or impaired fertility.
• There are no adequate, well-controlled studies of famotidine in pregnant women.
• This product should not be used during pregnancy unless directed by a physician, and only if the potential benefit to the mother outweighs the possible risk to the developing baby.

• Famotidine passes into breast milk, so nursing mothers should either avoid this medication or stop breastfeeding while using it.

• No dose adjustment is needed based on age alone.
• Because famotidine is cleared mainly by the kidneys and older adults are more likely to have reduced kidney function, it is reasonable to check kidney function and be cautious with dose selection in this age group.

• Safety and effectiveness in children under 12 years of age have not been established, and this product should not be given to children in that age range.

• Adults and children 12 years of age and older: take one tablet (20 mg) to relieve heartburn, acid indigestion, or sour or upset stomach.
• To prevent symptoms, take one tablet 10 to 15 minutes before eating food or drinking a beverage expected to cause heartburn.
• Swallow the tablet whole with a glass of water; do not take more than one tablet at a time, and do not take more than two tablets (40 mg total) in 24 hours.
• Do not use continuously for more than two weeks without consulting a physician.
• In patients with moderate to severe kidney impairment, the dose may need to be reduced by half, or the interval between doses extended to 36 to 48 hours, based on clinical response.

• Headache may occur.
• Diarrhea may occur.
• Upper respiratory infection symptoms may occur.
• Vomiting may occur.
• Constipation may occur.
• Nausea may occur.
• Sore throat (pharyngitis) may occur.
• Flu-like symptoms may occur.
• Back pain may occur.
• Skin rash may occur.

Serious side effects require immediate discussion with the prescriber or emergency care.

• Severe allergic reactions, including hives, swelling of the face or throat (angioedema), and anaphylaxis, may occur rarely.
• Liver enzyme abnormalities and, rarely, jaundice (yellowing of the skin or eyes) may occur.
• Slow heart rate, heart block, and other irregular heart rhythms have been reported rarely.
• Severe skin reactions such as toxic epidermal necrolysis have been reported very rarely with this class of medication.
• Blood disorders such as low platelet count, low white blood cell count, or bone marrow suppression have been reported rarely.
• Confusion, agitation, hallucinations, or other mental status changes have been reported, particularly in patients with reduced kidney function.
• Seek prompt medical attention for difficulty or pain swallowing, unexplained weight loss, black or tarry stools, persistent vomiting, chest pain, or facial swelling, since these can indicate a more serious underlying problem or a serious reaction.

• Use with caution in patients over 40 experiencing heartburn for the first time, or those with unexplained weight loss, who should consult a physician before use.
• Use with caution in patients with a prior history of stomach ulcer complications or unintended weight loss along with new digestive symptoms.
• Use with caution in patients with moderate or severe kidney impairment, since drug clearance is reduced and central nervous system side effects are more likely.
• Use with caution in patients taking nonsteroidal anti-inflammatory drugs, who should check with a physician or pharmacist before adding this product.
• Patients experiencing dizziness or drowsiness while taking famotidine should avoid driving or operating machinery until they know how the medication affects them.
• Further medical evaluation is needed if symptoms persist beyond two weeks, if two 14-day treatment courses are needed within six weeks, or if heartburn is frequent (more than three times a week) or severe.

• Contraindicated in patients with known hypersensitivity to famotidine or to any ingredient in the tablet.
• Contraindicated in patients with a history of hypersensitivity to other H2-receptor antagonists, due to cross-sensitivity within this drug class.

• Should not be used together with other H2-receptor antagonist products.
• Co-administration with the antifungal agents posaconazole oral suspension or itraconazole can significantly lower their blood levels and reduce their effectiveness against infection.
• Co-administration with the tyrosine kinase inhibitors dasatinib, erlotinib, gefitinib, or pazopanib can reduce their blood levels and effectiveness, so this combination is not recommended.
• In patients on chronic hemodialysis, famotidine can blunt the phosphate-lowering effect of calcium carbonate.
• Antacids containing aluminum hydroxide or magnesium hydroxide may be taken together with famotidine if needed, as they do not affect its absorption or effectiveness.
• Unlike some older H2-blockers, famotidine does not meaningfully affect the metabolism of other drugs processed by the liver's cytochrome P450 system.

• Famotidine can be taken with or without food; food may slightly increase its absorption, but this has no meaningful clinical effect.
• For symptom prevention, take the dose 10 to 15 minutes before eating or drinking something known to trigger heartburn.

• Take as needed for symptom relief, or 10 to 15 minutes before a meal or beverage likely to cause heartburn, not exceeding two tablets in 24 hours.

• Store between 15 and 30 degrees C in the original packaging, protected from light.

• This medication reduces stomach acid to relieve or prevent heartburn, acid indigestion, and upset stomach.
• Take one tablet as needed for symptoms, or 10 to 15 minutes before a meal expected to cause heartburn, without exceeding two tablets in 24 hours or using it continuously for more than two weeks.
• Common effects include headache, diarrhea, constipation, and mild stomach upset.
• Contact a doctor promptly for difficulty or pain swallowing, black or tarry stools, persistent vomiting, unexplained weight loss, or signs of an allergic reaction such as facial swelling or hives.
• It can be taken with or without food, though taking it shortly before a trigger meal helps prevent symptoms.
• Store the tablets at room temperature, protected from light, and see a doctor if symptoms persist beyond two weeks or keep recurring.