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Hydrogen Sulfide Toxicity

  • Author: Chip Gresham, MD, FACEM; Chief Editor: Asim Tarabar, MD  more...
Updated: Jan 27, 2014


Hydrogen sulfide (H2 S) is a colorless, flammable gas that has strong odor of rotten eggs. H2 S poisoning is a rarity, mainly observed in industrial settings. However, the deliberate mixture of household chemicals to create hydrogen sulfide is increasingly used as means of committing suicide, and these cases pose a potential risk for first responders. Emergency physicians must be aware of the presentation and management of hydrogen sulfide poisoning because rapid identification and treatment is essential for recovery.



Significant hydrogen sulfide poisoning usually occurs by inhalation. Local irritant effects, along with arrest of cellular respiration, may follow. Hydrogen sulfide forms a complex bond to the ferric moiety causing inhibition of mitochondrial cytochrome oxidase (iron-containing protein), thereby arresting aerobic metabolism in an effect similar to cyanide toxicity. Very high lipid solubility allows it to penetrate easily through biologic membranes.

As a cellular poison, hydrogen sulfide affects all organs, particularly the CNS and pulmonary system. The spectrum of illness depends on the concentration and duration of exposure, with concentration being more important than duration. High concentrations (>700 ppm or >975 mg/m3) have the potential to cause sudden death, theoretically due to hydrogen sulfide’s effect on the brainstem respiratory center.



Hydrogen sulfide most often is encountered as a byproduct of the petroleum, viscose rayon, rubber, and mining industries. The petroleum industry is responsible for most cases of hydrogen sulfide toxicity in North America. Organic decomposition of sulfur compounds in sewers, barns, liquid manure pits, ships' holds, and sulfur springs also produces hydrogen sulfide. In nature, hydrogen sulfide can be found in caves, sulfur springs, underground deposits of natural gas, or as result of volcanic eruptions.

The use of hydrogen sulfide as a means of committing suicide became a trend in Japan in 2007.[1] In these cases, bath sulfur was mixed with toilet bowl cleaner to produce the gas. Subsequently, the practice spread to the United States—facilitated by Web sites providing instructions on the technique—and its use appears to be increasing.[1, 2]

In these cases, hydrogen sulfide is created by mixing household chemicals (eg, an acidic detergent such as a toilet bowl cleaner, which acts as a proton donor, and a sulfur source such as a pesticide or bath salts), leading to the terms detergent suicide and chemical suicide. These are mixed in an enclosed space, such as a closet or an automobile, and despite the fact that suicide victims often place warning signs on closet doors or car windows, rescue workers and others entering the space have been affected.[2]



In the United States from 1999 to 2007, 45 deaths from hydrogen sulfide exposure occurred, all of them unintentional.[1] In occupationally-related hydrogen sulfide deaths, 25% of fatalities usually involve rescuers, professionals, or bystanders.[3]

Since 2008, approximately 2000 people in Japan have committed suicide by inhaling hydrogen sulfide.[4] In the United States, use of hydrogen sulfide for suicide reportedly resulted in 2 deaths in 2008, 10 in 2009, and 18 in 2010; however, the incidence is probably underreported.[1] In addition to deaths, at least 80% of hydrogen sulfide suicides “have resulted in injuries to police officers, firefighters, emergency workers or civilians exposed to the gas.”[4]



Low-level exposures to hydrogen sulfide usually produce local eye and mucous membrane irritation, while high-level exposures rapidly produce fatal systemic toxicity. Exposures of 700-800 ppm or greater can cause loss of consciousness and cardiopulmonary arrest. Complications include the following:

  • Acute respiratory distress syndrome
  • Acute myocardial infarction
  • Delayed neuropsychiatric sequelae

Occurrence of long-term neurologic sequelae from hydrogen sulfide exposure is unknown but appears to be linked to longer sublethal exposures. Paradoxically, high-concentration exposures of hydrogen sulfide may have no long-term effects.

Contributor Information and Disclosures

Chip Gresham, MD, FACEM Emergency Medicine Physician and Medical Toxicologist, Department of Emergency Medicine, Clinical Director of Medication Safety, Middlemore Hospital; Senior Lecturer, Auckland University Medical School, New Zealand

Chip Gresham, MD, FACEM is a member of the following medical societies: American College of Emergency Physicians, American College of Medical Toxicology, Society for Academic Emergency Medicine, Emergency Medicine Residents' Association

Disclosure: Nothing to disclose.


Emma A Lawrey, MBChB, Dip Paeds, PG Cert ClinEd, FACEM Emergency Medicine Consultant and Clinical Toxicology Fellow, Department of Emergency Medicine, Middlemore Hospital, New Zealand

Emma A Lawrey, MBChB, Dip Paeds, PG Cert ClinEd, FACEM is a member of the following medical societies: Australasian College for Emergency Medicine

Disclosure: Nothing to disclose.

Chief Editor

Asim Tarabar, MD Assistant Professor, Director, Medical Toxicology, Department of Emergency Medicine, Yale University School of Medicine; Consulting Staff, Department of Emergency Medicine, Yale-New Haven Hospital

Disclosure: Nothing to disclose.


John G Benitez, MD, MPH Associate Professor, Department of Medicine, Medical Toxicology, Vanderbilt University Medical Center; Managing Director, Tennessee Poison Center

John G Benitez, MD, MPH is a member of the following medical societies: American Academy of Clinical Toxicology, American Academy of Emergency Medicine, American College of Medical Toxicology, American College of Occupational and Environmental Medicine, American College of Preventive Medicine, Undersea and Hyperbaric Medical Society, and Wilderness Medical Society

Disclosure: Nothing to disclose.

David C Lee, MD Research Director, Department of Emergency Medicine, Associate Professor, North Shore University Hospital and New York University Medical School

David C Lee, MD is a member of the following medical societies: American Academy of Emergency Medicine, American College of Emergency Physicians, American College of Medical Toxicology, and Society for Academic Emergency Medicine

Disclosure: Nothing to disclose.

Sujal Mandavia, MD, FRCP(C), FACEP Clinical Assistant Professor of Emergency Medicine, USC, Department of Emergency Medicine, Cedars-Sinai Medical Center, Los Angeles County-University of Southern California Medical Center

Sujal Mandavia, MD, FRCP(C), FACEP is a member of the following medical societies: Alpha Omega Alpha, American Academy of Emergency Medicine, and American College of Emergency Physicians

Disclosure: Nothing to disclose.

John T VanDeVoort, PharmD Regional Director of Pharmacy, Sacred Heart and St Joseph's Hospitals

John T VanDeVoort, PharmD is a member of the following medical societies: American Society of Health-System Pharmacists

Disclosure: Nothing to disclose.

  1. Reedy SJ, Schwartz MD, Morgan BW. Suicide fads: frequency and characteristics of hydrogen sulfide suicides in the United States. West J Emerg Med. 2011 Jul. 12(3):300-4. [Medline]. [Full Text].

  2. Goode E. Chemical Suicides, Popular in Japan, Are Increasing in the U.S. NY Times, June 18, 2011. Available at

  3. Fuller DC, Suruda AJ. Occupationally related hydrogen sulfide deaths in the United States from 1984 to 1994. J Occup Environ Med. 2000 Sep. 42(9):939-42. [Medline].

  4. Undefined. [Medline].

  5. Sams RN, Carver HW 2nd, Catanese C, Gilson T. Suicide with hydrogen sulfide. Am J Forensic Med Pathol. 2013 Jun. 34(2):81-2. [Medline].

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