Sodium Thiosulfate
Sodium Hyposulfite
Also known as: natrii thiosulfas · natrium thiosulfuricum · sodium hyposulphite · sodium thiosulphate
Reviewed by the VetSheet Veterinary TeamUpdated Apr 5, 2026Evidence-based veterinary reference
Audited v13 dosing evidence
Reviewed non-calculator evidenceReviewed non-calculator evidence (1)
Evidence only — not for automatic calculation
Halogen toxicoses
TABLE 128.6. Agent: Sodium thiosulfate. Dosage: 1% solution as continuous bath to effect52. Species/Comments: Halogen toxicoses.
Doses are a clinical reference for licensed veterinary professionals. Always confirm against the current label and the individual patient.
Overview
Sodium thiosulfate is a versatile antidote primarily used in veterinary medicine for cyanide and arsenic poisoning.
- Cyanide Toxicity: Often used alone or in combination with sodium nitrite.
- Heavy Metal Poisoning: Used for arsenic or copper poisoning (with sodium molybdate), though efficacy for arsenic is debated.
- Chemotherapy Extravasation: Used to mitigate tissue damage from extravasation of cisplatin, carboplatin, dactinomycin, and doxorubicin.
- Topical Use: Occasionally used for fungal infections (Tinea).
Clinical Pearl: Because it is relatively non-toxic and inexpensive, it is a staple in emergency toxicology kits, especially for large animals exposed to cyanogenic plants.
Mechanism of action
Sodium thiosulfate acts primarily as an exogenous sulfur donor.
- Cyanide Antidote: It provides sulfur to the enzyme rhodanese (thiosulfate cyanide sulfurtransferase). Rhodanese catalyzes the conversion of highly toxic cyanide → relatively non-toxic thiocyanate ion, which is then safely excreted in the urine.
- Heavy Metal Chelation: The sulfate moiety is presumed to react with and chelate metals like arsenic, facilitating their removal from the body.
- Topical Antifungal: Activity is likely due to the slow release of colloidal sulfur.
Safety & warnings
Contraindications
- None absolute
Adverse effects
- Profuse diarrhea (with large oral doses)
Precautions
There are no absolute contraindications. Injectable forms should be given slowly IV. Safe use during pregnancy has not been established (FDA Category C); use when benefits outweigh potential risks.
Drug interactions
Not compatible when mixed together
Monitoring
- Clinical efficacy (resolution of toxicity signs)
- Hydration status (if diarrhea occurs from oral dosing)
Pharmacokinetics
Absorption
Relatively poorly absorbed from the GI tract. When substantial doses are given PO, it acts as a saline cathartic.
Distribution
Distributed in the extracellular fluid.
Elimination
Rapidly excreted via the urine.
Overdose
The drug is relatively non-toxic. Large doses by mouth may cause profuse diarrhea. Injectable forms should be given slowly IV.
Available products
Formulations
- Injection
- Crystals/Powder
Human-labeled
- Sodium Thiosulfate for Injection: 10% (100 mg/mL, as pentahydrate) & 25% (250 mg/mL as pentahydrate) preservative-free in 10 mL & 50 mL single-use vials
Regulatory status
No regulatory data for: 🇺🇸 US · 🇪🇺 EU · 🇬🇧 UK · 🇭🇰 HK · 🇹🇼 TW · 🇯🇵 JP · 🇰🇷 KR · 🇦🇺 AU
Storage & stability
Store at room temperature unless otherwise stated by the manufacturer. Crystals should be stored in tight containers. Not compatible mixed with cyanocobalamin.
Client information
Sodium thiosulfate is typically administered in a hospital setting for emergency treatment of poisoning (like cyanide or arsenic) or to treat tissue damage from chemotherapy leaks.
- If your pet receives this medication orally, it may cause profuse diarrhea.
- Ensure your pet has access to plenty of fresh water if diarrhea occurs, and follow your veterinarian's instructions closely.
VetSheet drug reference is intended for licensed veterinary professionals as a clinical decision-support aid, not a substitute for professional judgement or the manufacturer’s current label.