Pharmacology · Specific antidotes
Sodium thiosulfate !
A sulfur donor that lets the enzyme rhodanese turn cyanide into thiocyanate, which the kidneys excrete. Given after sodium nitrite.
Updated 2026-11-01
Mechanism of action
The body's main route for removing cyanide is to attach a sulfur atom to it, making thiocyanate, which is far less toxic and leaves in urine. Rhodanese and related sulfurtransferases do this, but the sulfur supply runs out in poisoning. Sodium thiosulfate supplies the sulfur, speeding detoxification. It is given in sequence with sodium nitrite, or alongside hydroxocobalamin through another line.
- Cyanide is in the cells and blood
- Thiosulfate gives sulfur to rhodanese
- Cyanide becomes thiocyanate
- Kidneys excrete thiocyanate
Pharmacokinetics
- Metabolism
- Mostly used in sulfur reactions; part is excreted unchanged
- Elimination
- Kidneys, as thiosulfate and as thiocyanate; elimination is slower in kidney failure
- Half-life
- Short, in the range of minutes to a few hours depending on the amount
Indications
- Serious or life-threatening acute cyanide poisoning, after sodium nitrite (or with hydroxocobalamin, through a separate line) Cyanide poisoning →
Adverse effects
Common
- Hypotension
- Headache and disorientation
- Nausea and vomiting
- Salty taste and a warm sensation
Contraindications
- No absolute contraindications; trace sulfites should not stop its use in an emergency
Key interactions
- Hydroxocobalamin
- Chemically incompatible: they are not given through the same intravenous line
What is monitored
- Blood pressure
- Lactate and acid-base status
- Kidney function
Administration and safety
- Slow intravenous infusion right after sodium nitrite
- A separate line from hydroxocobalamin
- Compatible with 5% dextrose and normal saline
Nursing care
- Check that nitrite was given and record the times of both antidotes
- Monitor blood pressure during the infusion
- Watch for nausea and vomiting and protect the airway
Pregnancy and breastfeeding
There are no adequate data in pregnancy, but untreated cyanide poisoning endangers mother and fetus, so it is used.
Test yourself
Think of the answer, then tap the question to see it.
Which enzyme uses thiosulfate to detoxify cyanide?
Rhodanese (thiosulfate sulfurtransferase), producing thiocyanate.
Into what is cyanide converted with thiosulfate, and how is it removed?
Into thiocyanate, which is much less toxic and is excreted by the kidneys.
What precaution applies when it is used with hydroxocobalamin?
They are chemically incompatible and need separate intravenous lines.
Related drugs
Related conditions
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Educational content on how drugs work; not a prescribing guide and no substitute for a health professional's advice. No doses are given.
Sources: DailyMed - SODIUM THIOSULFATE injection, solution (DailyMed (U.S. National Library of Medicine), 2026); DailyMed - SODIUM NITRITE injection, solution (DailyMed (U.S. National Library of Medicine), 2026); Guía para el Manejo de Emergencias Toxicológicas (Ministerio de Salud y Protección Social; Organización Panamericana de la Salud, 2017); eEML - Electronic Essential Medicines List (World Health Organization, 2025).
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