had prior antibodies or not. Even months after discontinuation, an elevated level of IgE in 6% of patients was still found in the study. Liver Cholestatic hepatitis, liver failure, hepatitis, and jaundice have been noted, and require immediate discontinuation of the drug. Blood tests can reveal an increase in liver enzymes or eosinophilia, although in rare instances, severe cases of hepatotoxicity may require a liver biopsy. Lungs Ranitidine and other histamine H2 receptor antagonists may increase the risk of pneumonia in hospitalised patients. They may also increase the risk of community-acquired pneumonia in adults and children. Blood Thrombocytopenia is a rare but known side effect. Drug-induced thrombocytopenia usually takes weeks or months to appear, but may appear within 12 hours of drug intake in a sensitised individual. Typically, the platelet count falls to 80% of normal, and thrombocytopenia may be associated with neutropenia and anemia. Skin Rash, including rare cases of erythema multiforme, and rare cases of hair loss and vasculitis have been seen. Precautions Disease-related concerns Relief of symptoms due to the use of ranitidine does not exclude the presence of a gastric malignancy. In addition, with kidney or liver impairment, ranitidine must be used with caution. It should be avoided in patients with porphyria, as it may precipitate an attack. Children In children, the use of gastric acid inhibitors has been associated with an increased risk for development of acute gastroenteritis and community-acquired pneumonia. A cohort analysis including over 11,000 neonates reported an association of H2 blocker use, and an increased incidence of necrotizing enterocolitis in very-low-birth-weight (VLBW) neonates. In addition, about a six-fold increase in mortality, necrotizing enterocolitis, and infection such as sepsis, pneumonia, urinary tract infection was reported in patients receiving ranitidine in a cohort analysis of 274 VLBW neonates. Drug tests Ranitidine may return a false positive result with some commercial urine drug screening kits for testing for drugs of abuse. Cancer-causing impurities In September 2019, the U.S. Food and Drug Administration (FDA) learned that some ranitidine medicines, including some products sold under the brand name Zantac, contained a nitrosamine impurity called N-nitrosodimethylamine (NDMA), classified as a probable human carcinogen, at low levels. Health Canada announced that it was assessing NDMA in ranitidine and requested that manufacturers stop the distribution of ranitidine products in Canada until the NDMA levels in the products are found to be safe. Health Canada announced that ranitidine drugs were being