Hydrogen sulfide toxicity - Revision history

Danbot: Strip excess bold

2026-03-22T09:30:32Z

Strip excess bold

← Revisión anterior		Revisión del 09:30 22 mar 2026
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	*"Rotten egg" odor at low concentrations (detectable at ~0.5 ppb)<ref name="ATSDR">Hydrogen Sulfide Medical Management Guidelines. Agency for Toxic Substances and Disease Registry (ATSDR). CDC.</ref>		*"Rotten egg" odor at low concentrations (detectable at ~0.5 ppb)<ref name="ATSDR">Hydrogen Sulfide Medical Management Guidelines. Agency for Toxic Substances and Disease Registry (ATSDR). CDC.</ref>
	*WARNING: Odor is NOT a reliable safety indicator — olfactory nerve fatigue occurs at ≥100 ppm (within 2-15 minutes), causing complete loss of smell at the very concentrations that are dangerous<ref name="StatPearls"/>		*WARNING: Odor is NOT a reliable safety indicator — olfactory nerve fatigue occurs at ≥100 ppm (within 2-15 minutes), causing complete loss of smell at the very concentrations that are dangerous<ref name="StatPearls"/>
	*Heavier than air → accumulates in ~~'''~~enclosed, low-lying, and poorly ventilated spaces~~'''~~ (sewers, manure pits, tanks)		*Heavier than air → accumulates in enclosed, low-lying, and poorly ventilated spaces (sewers, manure pits, tanks)
	*Encountered in:		*Encountered in:
	**Oil and gas industry (primary chemical hazard of natural gas production)		**Oil and gas industry (primary chemical hazard of natural gas production)
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	**Mining, smelting		**Mining, smelting
	**Hot springs, volcanic areas		**Hot springs, volcanic areas
	*Suicide method ("detergent suicide"~~'''~~):~~'''~~ mixing acidic household cleaners (toilet bowl cleaner) with sulfur-containing products (bath salts, lime sulfur pesticide) to generate H₂S in an enclosed space — increasing in prevalence<ref name="Tintinalli"/>		*Suicide method ("detergent suicide"): mixing acidic household cleaners (toilet bowl cleaner) with sulfur-containing products (bath salts, lime sulfur pesticide) to generate H₂S in an enclosed space — increasing in prevalence<ref name="Tintinalli"/>
	*Most fatalities occur in '''confined spaces'''; rescuers entering without SCBA frequently become secondary victims<ref name="ATSDR"/>		*Most fatalities occur in '''confined spaces'''; rescuers entering without SCBA frequently become secondary victims<ref name="ATSDR"/>
	*Children are at higher risk at the same ambient concentration due to higher minute volume:weight ratios and shorter stature (gas settles near the ground)<ref name="ATSDR"/>		*Children are at higher risk at the same ambient concentration due to higher minute volume:weight ratios and shorter stature (gas settles near the ground)<ref name="ATSDR"/>
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	**Identical mechanism to [[Cyanide poisoning\|cyanide]]		**Identical mechanism to [[Cyanide poisoning\|cyanide]]
	**Tissues with high oxygen demand (brain, heart) are most sensitive		**Tissues with high oxygen demand (brain, heart) are most sensitive
	*Causes ~~'''~~lactate accumulation and metabolic acidosis~~'''~~ from impaired oxidative phosphorylation		*Causes lactate accumulation and metabolic acidosis from impaired oxidative phosphorylation
	*Causes ~~'''~~hyperpolarization of potassium-mediated neuronal channels~~'''~~ → CNS depression<ref name="Tintinalli"/>		*Causes hyperpolarization of potassium-mediated neuronal channels → CNS depression<ref name="Tintinalli"/>
	*Potentiates neuronal inhibitory mechanisms; alters brain neurotransmitter content		*Potentiates neuronal inhibitory mechanisms; alters brain neurotransmitter content
	*Direct mucosal irritant → conjunctivitis, pulmonary edema		*Direct mucosal irritant → conjunctivitis, pulmonary edema
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	*SCBA is mandatory for any responder entering the hot zone		*SCBA is mandatory for any responder entering the hot zone
	*Chemical-protective clothing is generally NOT needed (H₂S is not significantly absorbed through skin)		*Chemical-protective clothing is generally NOT needed (H₂S is not significantly absorbed through skin)
	*In ~~'''~~detergent suicide~~'''~~ scenarios:		*In detergent suicide scenarios:
	**Approach with extreme caution; do not enter enclosed space (car, bathroom) without respiratory protection		**Approach with extreme caution; do not enter enclosed space (car, bathroom) without respiratory protection
	**Look for warning signs posted by the patient		**Look for warning signs posted by the patient
	**Ventilate the space before entry		**Ventilate the space before entry
	*Patients exposed only to H₂S gas do ~~'''~~not~~'''~~ generally require decontamination		*Patients exposed only to H₂S gas do not generally require decontamination
	*H₂S burns to produce ~~'''~~sulfur dioxide (SO₂)~~'''~~ — a secondary hazard if ignited		*H₂S burns to produce sulfur dioxide (SO₂) — a secondary hazard if ignited

	==Clinical features==		==Clinical features==
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	*Bronchospasm, wheezing		*Bronchospasm, wheezing
	*Rales, rhonchi		*Rales, rhonchi
	*Pulmonary edema — may be immediate or ~~'''~~delayed up to 72 hours~~'''~~<ref name="ATSDR"/>		*Pulmonary edema — may be immediate or delayed up to 72 hours<ref name="ATSDR"/>
	*[[ARDS]]		*[[ARDS]]
	*Central respiratory arrest at high concentrations		*Central respiratory arrest at high concentrations
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	===Labs===		===Labs===
	*ABG/VBG: metabolic acidosis with elevated lactate + ~~'''~~normal or elevated PaO₂/SaO₂~~'''~~ (cellular asphyxiant — oxygen delivery is adequate but cells cannot use it)		*ABG/VBG: metabolic acidosis with elevated lactate + normal or elevated PaO₂/SaO₂ (cellular asphyxiant — oxygen delivery is adequate but cells cannot use it)
	**Classic finding: lactic acidosis with normal oxygen saturation (unless concurrent pulmonary edema reduces oxygenation)		**Classic finding: lactic acidosis with normal oxygen saturation (unless concurrent pulmonary edema reduces oxygenation)
	*Serum lactate: elevated (reflects impaired oxidative phosphorylation)		*Serum lactate: elevated (reflects impaired oxidative phosphorylation)
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	==Management==		==Management==
	===Immediate===		===Immediate===
	*Remove from exposure — ensure scene safety; do ~~'''~~not~~'''~~ enter confined space without SCBA		*Remove from exposure — ensure scene safety; do not enter confined space without SCBA
	*100% high-flow oxygen via NRB mask — cornerstone of treatment		*100% high-flow oxygen via NRB mask — cornerstone of treatment
	**Competes with H₂S for cytochrome oxidase binding		**Competes with H₂S for cytochrome oxidase binding
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	*Mechanism: binds sulfide directly, forming sulfhydroxocobalamin		*Mechanism: binds sulfide directly, forming sulfhydroxocobalamin
	*Animal models demonstrate prevention of PEA cardiac arrest when given early<ref name="Haouzi2015"/>		*Animal models demonstrate prevention of PEA cardiac arrest when given early<ref name="Haouzi2015"/>
	*Emerging as the ~~'''~~preferred antidote~~'''~~ over nitrites due to safer side-effect profile (does not induce methemoglobinemia) and efficacy against both H₂S and cyanide		*Emerging as the preferred antidote over nitrites due to safer side-effect profile (does not induce methemoglobinemia) and efficacy against both H₂S and cyanide
	*[[Cobinamide]] (vitamin B₁₂ analog) shows promise in animal studies as a potentially superior antidote with greater sulfide-binding capacity<ref name="Jiang2016">Jiang J et al. Hydrogen Sulfide — Mechanisms of Toxicity and Development of an Antidote. ''Sci Rep''. 2016;6:20831.</ref><ref name="Brenner2014">Brenner M et al. The vitamin B₁₂ analog cobinamide is an effective hydrogen sulfide antidote in a lethal rabbit model. ''Clin Toxicol (Phila)''. 2014;52(5):490-497.</ref>		*[[Cobinamide]] (vitamin B₁₂ analog) shows promise in animal studies as a potentially superior antidote with greater sulfide-binding capacity<ref name="Jiang2016">Jiang J et al. Hydrogen Sulfide — Mechanisms of Toxicity and Development of an Antidote. ''Sci Rep''. 2016;6:20831.</ref><ref name="Brenner2014">Brenner M et al. The vitamin B₁₂ analog cobinamide is an effective hydrogen sulfide antidote in a lethal rabbit model. ''Clin Toxicol (Phila)''. 2014;52(5):490-497.</ref>

	====Nitrite therapy (alternative)====		====Nitrite therapy (alternative)====
	*May use the ~~'''~~nitrite component~~'''~~ of the cyanide antidote kit — do ~~'''~~NOT~~'''~~ give the thiosulfate portion (thiosulfate is the product of H₂S detoxification and does not help)<ref name="Goldfrank">Goldfrank et al. Hydrogen Sulfide Poisoning. In: Goldfrank et al. Goldfrank's Toxicologic Emergencies. New York, NY: McGraw Hill. 2002. 1504-1507.</ref>		*May use the nitrite component of the cyanide antidote kit — do NOT give the thiosulfate portion (thiosulfate is the product of H₂S detoxification and does not help)<ref name="Goldfrank">Goldfrank et al. Hydrogen Sulfide Poisoning. In: Goldfrank et al. Goldfrank's Toxicologic Emergencies. New York, NY: McGraw Hill. 2002. 1504-1507.</ref>
	*Mechanism: nitrites induce methemoglobinemia; methemoglobin (Fe³⁺) has high affinity for sulfide → converts it to the less toxic sulfmethemoglobin		*Mechanism: nitrites induce methemoglobinemia; methemoglobin (Fe³⁺) has high affinity for sulfide → converts it to the less toxic sulfmethemoglobin
	*[[Amyl nitrite]] inhaled (pearls crushed and inhaled) — may be used as a bridge		*[[Amyl nitrite]] inhaled (pearls crushed and inhaled) — may be used as a bridge
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	==Disposition==		==Disposition==
	*Asymptomatic patients with possible low-level exposure: observe for ~~'''~~minimum 4-6 hours~~'''~~; if asymptomatic with normal labs and CXR, may discharge with return precautions for delayed pulmonary edema (up to 72 hours)<ref name="ATSDR"/>		*Asymptomatic patients with possible low-level exposure: observe for minimum 4-6 hours; if asymptomatic with normal labs and CXR, may discharge with return precautions for delayed pulmonary edema (up to 72 hours)<ref name="ATSDR"/>
	*Any symptomatic patient or significant exposure: admit, likely to ICU		*Any symptomatic patient or significant exposure: admit, likely to ICU
	**Continuous cardiac and pulse oximetry monitoring		**Continuous cardiac and pulse oximetry monitoring
	**Serial ABGs, lactate, CXR		**Serial ABGs, lactate, CXR
	**Watch for ~~'''~~delayed pulmonary edema~~'''~~ (may develop up to 72 hours after exposure)<ref name="ATSDR"/>		**Watch for delayed pulmonary edema (may develop up to 72 hours after exposure)<ref name="ATSDR"/>
	*"Knockdown" patients (even with apparent rapid recovery): admit for observation — high risk for persistent or delayed neurologic sequelae<ref name="StatPearls"/>		*"Knockdown" patients (even with apparent rapid recovery): admit for observation — high risk for persistent or delayed neurologic sequelae<ref name="StatPearls"/>
	*Outpatient follow-up:		*Outpatient follow-up:

Danbot: Add MedicationDose entry for hydroxocobalamin

2026-03-20T21:19:18Z

Add MedicationDose entry for hydroxocobalamin

@@ Línea 213: / Línea 213: @@
 *Toxicology consultation for all significant exposures
 *Contact [[Poison control]] (1-800-222-1222 in the US) for all cases
 ==See Also==

Danbot: Formatting: moved intro to Background bullets, removed excessive bold, added DDX template

2026-03-19T15:48:07Z

Formatting: moved intro to Background bullets, removed excessive bold, added DDX template

Show changes

Ostermayer at 23:35, 17 March 2026

2026-03-17T23:35:26Z

Show changes

Rossdonaldson1: /* Differential Diagnosis */

2021-09-25T11:10:24Z

Differential Diagnosis

← Revisión anterior		Revisión del 11:10 25 sep 2021
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	==Differential Diagnosis==		==Differential Diagnosis==
	*[[Cyanide]] Toxicity
	*[[Hydrocarbons]] Toxicity

	{{Toxic gas exposure DDX}}		{{Toxic gas exposure DDX}}

Rossdonaldson1: /* Differential Diagnosis */

2021-09-25T11:06:28Z

Differential Diagnosis

← Revisión anterior		Revisión del 11:06 25 sep 2021
Línea 23:		Línea 23:

	==Differential Diagnosis==		==Differential Diagnosis==
	*[[Carbon Monoxide]] Toxicity
	*[[Cyanide]] Toxicity		*[[Cyanide]] Toxicity
	*[[Hydrocarbons]] Toxicity		*[[Hydrocarbons]] Toxicity
	*[[Smoke Inhalation Injury]]

	{{Toxic gas exposure DDX}}		{{Toxic gas exposure DDX}}

Rossdonaldson1: /* Differential Diagnosis */

2021-09-25T11:05:49Z

Differential Diagnosis

← Revisión anterior		Revisión del 11:05 25 sep 2021
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	*[[Hydrocarbons]] Toxicity		*[[Hydrocarbons]] Toxicity
	*[[Smoke Inhalation Injury]]		*[[Smoke Inhalation Injury]]

			{{Toxic gas exposure DDX}}

	==Evaluation==		==Evaluation==

Rossdonaldson1: Rossdonaldson1 moved page Hydrogen Sulfide to Hydrogen sulfide toxicity

2020-08-12T17:46:14Z

Rossdonaldson1 moved page Hydrogen Sulfide to Hydrogen sulfide toxicity

← Revisión anterior	Revisión del 17:46 12 ago 2020
(Sin diferencias)

Mholtz: Text replacement - "prn" to "PRN"

2017-07-07T07:28:51Z

Text replacement - "prn" to "PRN"

← Revisión anterior		Revisión del 07:28 7 jul 2017
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	*100% oxygen		*100% oxygen
	*[[Hydroxocobalamin]] (Cyanokit)		*[[Hydroxocobalamin]] (Cyanokit)
	**5 g over 15 min to start, followed by a second dose ~~prn~~		**5 g over 15 min to start, followed by a second dose PRN
	**If given as early as possible, has been shown in animal models to prevent PEA<ref>Haouzi P et al. High-dose hydroxocobalamin administered after H2S exposure counteracts sulfide-poisoning-induced cardiac depression in sheep. Clin Toxicol (Phila). 2015 Jan;53(1):28-36.</ref>		**If given as early as possible, has been shown in animal models to prevent PEA<ref>Haouzi P et al. High-dose hydroxocobalamin administered after H2S exposure counteracts sulfide-poisoning-induced cardiac depression in sheep. Clin Toxicol (Phila). 2015 Jan;53(1):28-36.</ref>
	**[[Cobinamide]], a vitamin B12 analog, shows promise as first line for H2S toxicity<ref>Jiang J et al. Hydrogen Sulfide—Mechanisms of Toxicity and Development of an Antidote. Nature. Scientific Reports 6, Article number: 20831 (2016).</ref><ref>Brenner M et al. The vitamin B12 analog cobinamide is an effective hydrogen sulfide antidote in a lethal rabbit model. Clin Toxicol (Phila). 2014 Jun;52(5):490-7.</ref>		**[[Cobinamide]], a vitamin B12 analog, shows promise as first line for H2S toxicity<ref>Jiang J et al. Hydrogen Sulfide—Mechanisms of Toxicity and Development of an Antidote. Nature. Scientific Reports 6, Article number: 20831 (2016).</ref><ref>Brenner M et al. The vitamin B12 analog cobinamide is an effective hydrogen sulfide antidote in a lethal rabbit model. Clin Toxicol (Phila). 2014 Jun;52(5):490-7.</ref>

ClaireLewis: /* Management */

2017-05-17T17:24:57Z

Management

← Revisión anterior		Revisión del 17:24 17 may 2017
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	*Can give nitrite component of cyanide antidote kit (do NOT give the thiosulfate portion):		*Can give nitrite component of cyanide antidote kit (do NOT give the thiosulfate portion):
	**Theoretically increasing methemoglobin formation in blood will cause conversion of sulfide to sulfmethemoglonin (less toxic)		**Theoretically increasing methemoglobin formation in blood will cause conversion of sulfide to sulfmethemoglonin (less toxic)
	**Amyl nitrite		**[[Amyl nitrite]]
	**Sodium nitrite (3% NaNO2) IV over 2-4 minutes; adult dose 10 mL		**[[Sodium nitrite]] (3% NaNO2) IV over 2-4 minutes; adult dose 10 mL
	**Obtain methemoglobin level 30 minutes after dose (desired level < 30%)		**Obtain methemoglobin level 30 minutes after dose (desired level < 30%)
	*Hyperbaric oxygen therapy (though not proven to have any benefit)<ref>Goldfrank et. al. Hydrogen Sulfide Poisoning. In: Goldfrank et. al. Goldfrank’s Toxicologic Emergencies. New York, NY: McGraw Hill. 2002. 1504-1507. </ref>		*Hyperbaric oxygen therapy (though not proven to have any benefit)<ref>Goldfrank et. al. Hydrogen Sulfide Poisoning. In: Goldfrank et. al. Goldfrank’s Toxicologic Emergencies. New York, NY: McGraw Hill. 2002. 1504-1507. </ref>