Famotidine

Prolonged QT interval has been reported in patients with renal dysfunction. The FDA has received reports of torsades de pointes occurring with famotidine (Poluzzi 2009).

Prolonged treatment (≥2 years) may lead to vitamin B12 malabsorption and subsequent vitamin B12 deficiency. The magnitude of the deficiency is dose-related and the association is stronger in females and those younger in age ( Disease-related concerns:

Relief of symptoms does not preclude the presence of a gastric malignancy.

Use with caution in patients with moderate to severe renal impairment (CrCl Concurrent drug therapy issues:

Potentially significant interactions may exist, requiring dose or frequency adjustment, additional monitoring, and/or selection of alternative therapy. Consult drug interactions database for more detailed information. Special populations:

Use of gastric acid inhibitors, including proton pump inhibitors and H2 blockers, has been associated with an increased risk for development of acute gastroenteritis and community-acquired pneumonia in pediatric patients (Canani 2006). Dosage form specific issues:

Some dosage forms may contain benzyl alcohol and/or sodium benzoate/benzoic acid; benzoic acid (benzoate) is a metabolite of benzyl alcohol; large amounts of benzyl alcohol (≥99 mg/kg/day) have been associated with a potentially fatal toxicity (“gasping syndrome”) in neonates; the “gasping syndrome” consists of metabolic acidosis, respiratory distress, gasping respirations, CNS dysfunction (including convulsions, intracranial hemorrhage), hypotension, and cardiovascular collapse (AAP ["Inactive" 1997]; CDC 1982); some data suggests that benzoate displaces bilirubin from protein binding sites (Ahlfors 2001); avoid or use dosage forms containing benzyl alcohol and/or benzyl alcohol derivative with caution in neonates. See manufacturer’s labeling. Other warnings/precautions:

When used for self-medication (OTC), notify health care provider before use if any of the following are present: Frequent chest pain; frequent wheezing particularly with heartburn; nausea/vomiting; unexplained weight loss; stomach pain; heartburn >3 months; heartburn with light-headedness, sweating, or dizziness; chest pain or shoulder pain with shortness of breath; sweating; pain that spreads to arms, neck, or shoulders; light-headedness. Discontinue use and notify health care provider if heartburn continues or worsens, or if use is required >14 days.