{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,9,13]],"date-time":"2025-09-13T15:41:13Z","timestamp":1757778073605,"version":"3.41.2"},"reference-count":25,"publisher":"Frontiers Media SA","license":[{"start":{"date-parts":[[2025,5,8]],"date-time":"2025-05-08T00:00:00Z","timestamp":1746662400000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":["frontiersin.org"],"crossmark-restriction":true},"short-container-title":["Front. Med."],"abstract":"<jats:p>Methemoglobinemia is a condition caused by elevated levels of methemoglobin (MetHb) in the blood, a reduced form of hemoglobin that cannot properly bind to oxygen, interfering with delivery to tissues. If left untreated, this condition can be fatal. Phenazopyridine, an over-the-counter urinary tract analgesic, has been reported to cause methemoglobinemia in rare instances. In the present case, a 67-year-old patient demonstrated hypoxia and oral cyanosis in the setting of chronic phenazopyridine use and chronic obstructive pulmonary disease (COPD). A \u201cchocolate-brown\u201d coloration of his blood and an elevated MetHb level of 14.5% confirmed the diagnosis of methemoglobinemia. He was treated with methylene blue, ascorbic acid, bronchodilators, steroids, and supportive oxygen. This regimen led to a gradual improvement in the patient\u2019s clinical condition, including his hypoxia, cyanosis, and MetHb levels. This report illustrates a rare, unique case of phenazopyridine-induced methemoglobinemia and acute hypoxic respiratory failure in a patient with pre-existing COPD. In such patients, effective management requires a careful treatment approach directed at both methemoglobinemia and COPD.<\/jats:p>","DOI":"10.3389\/fmed.2025.1568949","type":"journal-article","created":{"date-parts":[[2025,5,8]],"date-time":"2025-05-08T04:13:29Z","timestamp":1746677609000},"update-policy":"https:\/\/doi.org\/10.3389\/crossmark-policy","source":"Crossref","is-referenced-by-count":2,"title":["Treatment for a rare case of phenazopyridine-induced methemoglobinemia: a case report and mini-review"],"prefix":"10.3389","volume":"12","author":[{"given":"Brendan M.","family":"Coyne","sequence":"first","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Syed M.","family":"Ishaq","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Anjani","family":"Thota","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Badal","family":"Thakkar","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1965","published-online":{"date-parts":[[2025,5,8]]},"reference":[{"year":"2024","author":"Ludlow","key":"ref1"},{"key":"ref2","doi-asserted-by":"publisher","first-page":"1666","DOI":"10.1002\/ajh.26340","article-title":"Recommendations for diagnosis and treatment of methemoglobinemia","volume":"96","author":"Iolascon","year":"2021","journal-title":"Am J Hematol"},{"key":"ref3","doi-asserted-by":"publisher","first-page":"265","DOI":"10.1097\/01.md.0000141096.00377.3f","article-title":"Acquired methemoglobinemia: a retrospective series of 138 cases at 2 teaching hospitals","volume":"83","author":"Ash-Bernal","year":"2004","journal-title":"Medicine (Baltimore)"},{"key":"ref4","doi-asserted-by":"publisher","first-page":"214","DOI":"10.1016\/s0196-0644(82)80502-7","article-title":"Methemoglobinemia","volume":"11","author":"Curry","year":"1982","journal-title":"Ann Emerg Med"},{"key":"ref5","article-title":"Phenazopyridine","volume-title":"StatPearls","author":"Eastham","year":"2024"},{"key":"ref6","doi-asserted-by":"publisher","first-page":"e227538","DOI":"10.1136\/bcr-2018-227538","article-title":"Methemoglobinaemia with chronic phenazopyridine ingestion","volume":"12","author":"Agrawal","year":"2019","journal-title":"BMJ Case Rep"},{"key":"ref7","doi-asserted-by":"publisher","first-page":"e33715","DOI":"10.7759\/cureus.33715","article-title":"Phenazopyridine-induced Methemoglobinemia: a case report","volume":"15","author":"Koch","year":"2023","journal-title":"Cureus"},{"key":"ref8","doi-asserted-by":"publisher","first-page":"45","DOI":"10.1186\/s12245-018-0208-5","article-title":"Acquired methemoglobinemia from phenazopyridine use","volume":"11","author":"Murphy","year":"2018","journal-title":"Int J Emerg Med"},{"key":"ref9","doi-asserted-by":"publisher","first-page":"845","DOI":"10.3390\/clinpract12060089","article-title":"A case of severe hypoxia caused by phenazopyridine-induced methemoglobinemia: a near fatal event from over-the-counter medication use","volume":"12","author":"Kc","year":"2022","journal-title":"Clin Pract"},{"key":"ref10","doi-asserted-by":"publisher","first-page":"bcr2012006756","DOI":"10.1136\/bcr-2012-006756","article-title":"Acquired methaemoglobinaemia related to phenazopyridine ingestion","volume":"2012","author":"Shahani","year":"2012","journal-title":"BMJ Case Rep"},{"key":"ref11","doi-asserted-by":"publisher","first-page":"143","DOI":"10.1016\/s0736-4679(03)00162-8","article-title":"Methemoglobinemia due to ingestion of at most three pills of pyridium in a 2-year-old: case report and review","volume":"25","author":"Gold","year":"2003","journal-title":"J Emerg Med"},{"key":"ref12","first-page":"427","article-title":"Methemoglobinemia caused by acute overdosage of phenazopyridine","volume":"122","author":"Randazzo","year":"1975","journal-title":"West J Med"},{"key":"ref13","doi-asserted-by":"publisher","first-page":"A6266","DOI":"10.1016\/j.chest.2023.07.4031","article-title":"A case of unexpected methemoglobinemia in the outpatient setting","volume":"164","author":"Mergey Devender","year":"2023","journal-title":"Chest"},{"key":"ref14","doi-asserted-by":"crossref","first-page":"A4945","DOI":"10.1164\/ajrccm-conference.2020.201.1_MeetingAbstracts.A4945","volume-title":"Phenazopyridine-induced Methemoglobinemia: Dysuria or asphyxiation, choose wisely! 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Case reports in drug induced lung disease","author":"Nasrullah","year":"2020"},{"key":"ref15","doi-asserted-by":"publisher","first-page":"325","DOI":"10.3390\/hematolrep15020034","article-title":"Phenazopyridine-induced methemoglobinemia in a Jehovah\u2019s witness treated with high-dose ascorbic acid due to methylene blue contradictions: a case report and review of the literature","volume":"15","author":"Menakuru","year":"2023","journal-title":"Hematol Rep"},{"key":"ref16","doi-asserted-by":"publisher","first-page":"003191","DOI":"10.12890\/2022_003191","article-title":"Phenazopyridine-induced methaemoglobinaemia the aftermath of dysuria treatment","volume":"9","author":"Hamza","year":"2022","journal-title":"Eur J Case Rep Intern Med"},{"key":"ref17","doi-asserted-by":"publisher","first-page":"A6187","DOI":"10.1016\/j.chest.2023.07.3980","article-title":"Uncommon, but not unseen: a potential cause of methemoglobinemia","volume":"164","author":"Stacy Amadife","year":"2023","journal-title":"Chest"},{"key":"ref18","doi-asserted-by":"publisher","first-page":"157","DOI":"10.1177\/106002808201600212","article-title":"Acquired methemoglobinemia and hemolytic anemia after usual doses of phenazopyridine","volume":"16","author":"Jeffery","year":"1982","journal-title":"Drug Intell Clin Pharm"},{"key":"ref19","doi-asserted-by":"publisher","first-page":"A387","DOI":"10.1016\/j.chest.2017.08.413","article-title":"Methemoglobinemia and anemia caused by pyridium overuse in an adult","volume":"152","author":"Duran","year":"2017","journal-title":"Chest"},{"key":"ref20","doi-asserted-by":"publisher","first-page":"1636","DOI":"10.1001\/archinte.1977.03630230104031","article-title":"Acute methemoglobinemia and hemolytic anemia with phenazopyridine: possible relation to acute renal failure","volume":"137","author":"Nathan","year":"1977","journal-title":"Arch Intern Med"},{"key":"ref21","doi-asserted-by":"publisher","first-page":"431","DOI":"10.1056\/NEJM196408272710902","article-title":"Methemoglobinemia and Heinz body hemolytic anemia due to phenazopyridine hydrochloride","volume":"271","author":"Greenberg","year":"1964","journal-title":"N Engl J Med"},{"key":"ref22","doi-asserted-by":"publisher","first-page":"147","DOI":"10.1016\/s0196-0644(80)80270-8","article-title":"Methemoglobinemia from overdose of phenazopyridine hydrochloride","volume":"9","author":"Zimmerman","year":"1980","journal-title":"Ann Emerg Med"},{"year":"2000","key":"ref23"},{"key":"ref24","doi-asserted-by":"publisher","first-page":"e58312","DOI":"10.7759\/cureus.58312","article-title":"Shades of blue: a case series of acquired methemoglobinemia","volume":"16","author":"Rathod","year":"2024","journal-title":"Cureus"},{"key":"ref25","doi-asserted-by":"publisher","first-page":"3284","DOI":"10.1364\/BOE.9.003284","article-title":"On the dysfunctional hemoglobins and cyanosis connection: practical implications for the clinical detection and differentiation of methemoglobinemia and sulfhemoglobinemia","volume":"9","author":"Askew","year":"2018","journal-title":"Biomed Opt Express"}],"container-title":["Frontiers in Medicine"],"original-title":[],"link":[{"URL":"https:\/\/www.frontiersin.org\/articles\/10.3389\/fmed.2025.1568949\/full","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,5,8]],"date-time":"2025-05-08T04:13:30Z","timestamp":1746677610000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.frontiersin.org\/articles\/10.3389\/fmed.2025.1568949\/full"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2025,5,8]]},"references-count":25,"alternative-id":["10.3389\/fmed.2025.1568949"],"URL":"https:\/\/doi.org\/10.3389\/fmed.2025.1568949","relation":{},"ISSN":["2296-858X"],"issn-type":[{"type":"electronic","value":"2296-858X"}],"subject":[],"published":{"date-parts":[[2025,5,8]]},"article-number":"1568949"}}