{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,2,19]],"date-time":"2026-02-19T09:54:46Z","timestamp":1771494886917,"version":"3.50.1"},"reference-count":21,"publisher":"MDPI AG","issue":"6","license":[{"start":{"date-parts":[[2022,10,27]],"date-time":"2022-10-27T00:00:00Z","timestamp":1666828800000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Clinics and Practice"],"abstract":"<jats:p>Methemoglobinemia is a rare blood disorder characterized by the oxidation of heme iron from ferrous (Fe2+) to ferric (Fe3+) state, which increases oxygen affinity and impairs oxygen release to the tissue causing hypoxia. It can be congenital or acquired; however, most cases are acquired and caused by exogenous substances such as medications, chemicals, and environmental substances. Phenazopyridine is an over-the-counter urinary analgesic medication commonly used for symptomatic relief of dysuria and has been reported to cause methemoglobinemia. However, only a handful of cases of phenazopyridine-induced methemoglobinemia have been reported. We present a case of an 89-year-old female who presented with severe hypoxia, shortness of breath, headache, nausea, and dizziness caused by phenazopyridine-induced methemoglobinemia. She was found to have a methemoglobin level of 21.5% and was treated with methylene blue, leading to a rapid improvement of her symptoms. She was taking one over-the-counter phenazopyridine 200 mg tablet three times daily for two weeks for her chronic dysuria. This case highlights the need to have a high index of suspicion of phenazopyridine-induced methemoglobinemia in a patient presenting with unexplained shortness of breath with a history of phenazopyridine use as it could lead to severe methemoglobinemia with hypoxia that could potentially be fatal if not promptly diagnosed.<\/jats:p>","DOI":"10.3390\/clinpract12060089","type":"journal-article","created":{"date-parts":[[2022,10,27]],"date-time":"2022-10-27T20:37:58Z","timestamp":1666903078000},"page":"845-851","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":11,"title":["A Case of Severe Hypoxia Caused by Phenazopyridine-Induced Methemoglobinemia: A near Fatal Event from Over-the-Counter Medication Use"],"prefix":"10.3390","volume":"12","author":[{"given":"Ojbindra","family":"KC","sequence":"first","affiliation":[{"name":"Department of Hospital Medicine, Faith Regional Health Services, Norfolk, NE 68701, USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Ananta","family":"Subedi","sequence":"additional","affiliation":[{"name":"Department of Hospital Medicine, Avera McKennan Hospital and University Health Center, Sioux Falls, SD 57105, USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Rakshya","family":"Sharma","sequence":"additional","affiliation":[{"name":"Department of Hospital Medicine, Avera McKennan Hospital and University Health Center, Sioux Falls, SD 57105, USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Punya Hari","family":"Dahal","sequence":"additional","affiliation":[{"name":"Department of Hospital Medicine, Faith Regional Health Services, Norfolk, NE 68701, USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Manisha","family":"Koirala","sequence":"additional","affiliation":[{"name":"Department of Hospital Medicine, Faith Regional Health Services, Norfolk, NE 68701, USA"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2022,10,27]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"1043","DOI":"10.1053\/j.jvca.2013.02.005","article-title":"Methemoglobinemia: A review and recommendations for management","volume":"28","author":"Cortazzo","year":"2014","journal-title":"J. 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