Sulfhemoglobinemia is a rare condition in which there is excess sulfhemoglobin (SulfHb) in the blood. The pigment is a greenish derivative of hemoglobin which cannot be converted back to normal, functional hemoglobin. It causes cyanosis even at low blood levels.

SymptomsCyanosis, urinary tract infection and chronic constipation
ComplicationsHypoxemia, methemoglobinemia, and hypoxia
Duration100-120 days (lifespan of red blood cells)
CausesSulfur medications such as phenacetin, metoclopramide, dapsone, phenzopyridine, and trimethoprim-sulfamethoxazole; hydrogen-sulfide-producing intestinal bacteria, such as Morganella morganii
Risk factorsPulmonary arteriovenous malformation
PreventionAvoidance of sulfur-containing compounds including drugs
TreatmentBlood transfusions

It is a rare blood condition in which the β-pyrrole ring of the hemoglobin molecule has the ability to bind irreversibly to any substance containing a sulfur atom.[1][2] When hydrogen sulfide (H2S) (or sulfide ions) and ferrous ions combine in the heme of hemoglobin, the blood is thus incapable of transporting oxygen to the tissues.



Symptoms include a blueish or greenish coloration of the blood (cyanosis), skin, and mucous membranes, even though a blood count test may not show any abnormalities in the blood. This discoloration is caused by greater than 5 grams per cent of deoxyhemoglobin, or 1.5 grams per cent of methemoglobin, or 0.5 grams per cent of sulfhemoglobin, all serious medical abnormalities.[citation needed]



Sulfhemoglobinemia is usually drug induced, with drugs associated with it including sulphonamides, such as sulfasalazine or sumatriptan. Another possible cause is occupational exposure to sulfur compounds.[citation needed]

It can also be caused by phenazopyridine.[3]





The condition generally resolves itself with erythrocyte (red blood cell) turnover, although blood transfusions can be necessary in extreme cases.[citation needed]

Notable cases


On June 8, 2007, Canadian anesthesiologists Dr. Stephan Schwarz, Dr. Giuseppe Del Vicario, and Dr. Alana Flexman presented an unusual case in The Lancet.[4] A 42-year-old male patient was brought into Vancouver's St. Paul's Hospital after falling asleep in a kneeling position, which caused compartment syndrome and a buildup of pressure in his legs. When doctors drew the man's blood prior to performing the surgery to relieve the pressure from the man's legs, they noted his blood was green. A sample of the blood was immediately sent to a lab. In this case, sulfhemoglobinemia was possibly caused by the patient taking higher-than-prescribed doses of sumatriptan.[5][6]


  1. ^ Gharahbaghian, Laleh; Massoudian, Bobby; DiMassa, Giancarlo (August 2009). "Methemoglobinemia and Sulfhemoglobinemia in Two Pediatric Patients after Ingestion of Hydroxylamine Sulfate". Western Journal of Emergency Medicine. 10 (3): 197–201. ISSN 1936-900X. PMC 2729224. PMID 19718385.
  2. ^ Curry, Steven (June 6, 2007). "14". In Shannon, Michael; Borron, Stephen; Burns, Michael (eds.). Haddad and Winchester's Clinical Management of Poisoning and Drug Overdose (4 ed.). Saunders. p. 289. doi:10.1016/B978-0-7216-0693-4.50019-0. ISBN 9780721606934. Archived from the original on July 28, 2021. Retrieved July 29, 2021.{{cite book}}: CS1 maint: bot: original URL status unknown (link)
  3. ^ Gopalachar AS, Bowie VL, Bharadwaj P (June 2005). "Phenazopyridine-induced sulfhemoglobinemia". Ann Pharmacother. 39 (6): 1128–30. doi:10.1345/aph.1E557. PMID 15886294. S2CID 22812461. Archived from the original on 2013-04-19.
  4. ^ Flexman AM, Del Vicario G, Schwarz SK (June 2007). "Dark green blood in the operating theatre". Lancet. 369 (9577): 1972. doi:10.1016/S0140-6736(07)60918-0. PMID 17560450. S2CID 39437785.
  5. ^ "Patient bleeds dark green blood", BBC News, 8 June 2007
  6. ^ "Dark Green Blood In The Operating Theatre" Archived 2007-07-11 at the Wayback Machine, Medical News Today, June 8, 2007