<p>Gastrointestinal Adverse Effects: Serious cases of gastrointestinal obstruction, ileus, subileus, gastrointestinal perforation, and fecal impaction have been reported in patients taking Lanthanum, some requiring surgery or hospitalization. During treatment with Lanthanum Carbonate, physicians and patients should remain vigilant for signs and symptoms of gastrointestinal disorders, especially constipation and abdominal pain/distention, which may indicate bowel obstruction, ileus, or subileus. Treatment with Lanthanum Carbonate should be re-evaluated in patients who develop severe constipation or other severe gastrointestinal signs and symptoms. Advise patients who are prescribed Lanthanum Carbonate Chewable Tablets to chew the tablet completely and not to swallow them whole. Serious gastrointestinal complications have been reported in association with unchewed or incompletely chewed tablets.</p>