BACKGROUND Sodium nitrite is known to induce methemoglobinemia and hypotension when ingested, but reports of intentional ingestion remain rare. METHODS We report five cases of severe methemoglobinemia secondary to large sodium nitrite ingestion that were reported to and managed by the California Poison Control System in 2019, resulting in three fatalities. The estimated doses ingested ranged from 15 grams to 113 grams, with one patient surviving after an ingestion of 60 grams. The highest documented methemoglobin level was 73%. The 2 patients who survived received methylene blue early in their clinical course. One patient required higher doses of methylene blue compared with other cases of nitrite-associated methemoglobinemia. In the patients who survived, all symptoms resolved within 24 h. WHY SHOULD AN EMERGENCY PHYSICIAN BE AWARE OF THIS?: These cases highlight the severe toxicity associated with intentional large sodium nitrite ingestion. In management, consideration should be given to administering higher initial or more frequent doses of methylene blue compared with standard practice. Given that sodium nitrite is readily accessible through online vendors, and is being circulated through various suicide forums, it has the potential to be more commonly encountered in the emergency department.