Dimercaprol
2,3-dimercapto-1-propanol
Also known as: BAL in Oil · Sulfactin Homburg · British anti-lewisite · dimercaptopropanol · dithioglycerol dimercaprolum · Dicaptol
Reviewed by the VetSheet Veterinary TeamUpdated Apr 5, 2026Evidence-based veterinary reference
Doses are a clinical reference for licensed veterinary professionals. Always confirm against the current label and the individual patient.
Dosing by species
🌎 NA — North America🌍 EU — Europe
Dogs
| Indication | Dose | Route | Frequency | Duration | Region |
|---|---|---|---|---|---|
| Arsenic toxicity | 2.5-5 mg/kg IM | IM | q4h for first 2 days; q8h on 3rd day; BID for next 10 days | Until recovery | 🌎 NA |
| Arsenic toxicity | 4 mg/kg IM | IM | q4-6h | Max 4 continuous days | 🌎 NA |
| Arsenic toxicity | 5 mg/kg IM loading dose, then 2.5 mg/kg IM | IM | q3-4h for two days, then progressively lengthen to q12h | Until recovery | 🌎 NA |
- Arsenic toxicity: Intensive supportive care required. 5 mg/kg dose only for acute cases and only for the first day. Give with sodium thiosulfate: 40-50 mg/kg IV as a 20% solution 2-3 times daily.
- Arsenic toxicity: Do not give for more than 4 continuous days.
- Arsenic toxicity: Loading dose of 5 mg/kg for acute cases only.
Cats
| Indication | Dose | Route | Frequency | Duration | Region |
|---|---|---|---|---|---|
| Arsenic toxicity | 2.5-5 mg/kg IM | IM | q4h for first 2 days; q8h on 3rd day; BID for next 10 days | Until recovery | 🌎 NA |
| Arsenic toxicity | 2.5-5 mg/kg IM | IM | q4h for first 2 days, then q12h | Until recovery | 🌎 NA |
| Arsenic toxicity | 4 mg/kg IM | IM | q4-6h | Max 4 continuous days | 🌎 NA |
| Arsenic toxicity | 5 mg/kg IM loading dose, then 2.5 mg/kg IM | IM | q3-4h for two days, then progressively lengthen to q12h | Until recovery | 🌎 NA |
- Arsenic toxicity: Intensive supportive care required. 5 mg/kg dose only for acute cases and only for the first day. Give with sodium thiosulfate.
- Arsenic toxicity: If ingestion was within 36 hours. Use emetics/gastric lavage if recent. Institute fluid therapy.
- Arsenic toxicity: Do not give for more than 4 continuous days.
- Arsenic toxicity: Loading dose of 5 mg/kg for acute cases only.
Horses
| Indication | Dose | Route | Frequency | Duration | Region |
|---|---|---|---|---|---|
| Arsenic toxicity | 5 mg/kg IM initially, followed by 3 mg/kg IM q6h for remainder of first day, then 1 mg/kg IM q6h | IM | q6h | 2 or more additional days | 🌎 NA |
| Arsenic toxicity | 5 mg/kg IM initially, followed by 3 mg/kg IM q6h for remainder of first day, then 1 mg/kg IM q6h | IM | q6h | Next 48 hours | 🌎 NA |
- Arsenic toxicity: Therapy is difficult due to large volumes required and painful IM route. Must be used acutely; delays significantly decrease effectiveness.
- Arsenic toxicity: Effective if administered within hours of ingestion. Wash off topical arsenic, empty digestive tract. Administer sodium thiosulfate PO and IV.
Cattle
| Indication | Dose | Route | Frequency | Duration | Region |
|---|---|---|---|---|---|
| Arsenic toxicity (no clinical signs) | 3 mg/kg IM | IM | q8h | — | 🌎 NA |
| Arsenic toxicity (clinical signs) | 6 mg/kg IM | IM | q8h | 3-5 days | 🌎 NA |
| Arsenic, lead or mercury poisoning | 2.5-5 mg/kg IM | IM | q4h | 2 days | 🌎 NA |
| Mercury toxicity | 3 mg/kg IM | IM | four times daily for 3 days, then twice daily | 13 days total | 🌎 NA |
- Arsenic, lead or mercury poisoning: Efficacy questionable unless given before signs appear or very early. Withdrawal info not available.
- Mercury toxicity: Treatment is often unsuccessful.
Swine
| Indication | Dose | Route | Frequency | Duration | Region |
|---|---|---|---|---|---|
| Mercury toxicity | 3 mg/kg IM | IM | four times daily for 3 days, then twice daily | 13 days total | 🌎 NA |
- Mercury toxicity: Treatment is often unsuccessful.
Doses are a clinical reference for licensed veterinary professionals. Always confirm against the current label and the individual patient.
Overview
Dimercaprol (also known as British Anti-Lewisite or BAL) is a heavy metal chelating agent primarily used in veterinary medicine to treat arsenic toxicity. It is also occasionally utilized for lead, mercury, and gold intoxications.
Originally developed during World War II as an antidote for Lewisite (an arsenic-based chemical warfare agent), it contains sulfhydryl groups that bind to heavy metals, preventing them from interfering with essential cellular enzymes.
Clinical Pearl: Dimercaprol is formulated in peanut oil and must be given via deep intramuscular injection, which can be quite painful. It is relatively ineffective for certain metals like selenium and is strictly contraindicated in iron, cadmium, and selenium poisoning because the resulting dimercaprol-metal complex is more toxic than the metal alone.
Mechanism of action
Heavy metals exert their toxic effects by binding to sulfhydryl (-SH) groups on essential cellular enzymes, leading to enzyme inactivation. Dimercaprol contains two sulfhydryl groups that act as "decoys."
- Dimercaprol + Heavy Metal → Heterocyclic Ring Complex
- This complex is more stable than the metal-enzyme bond, allowing the metal to be pulled away from the tissues and excreted via the kidneys and feces.
Mechanistic Note: The chelation is not irreversible. The complex can dissociate as dimercaprol concentrations decrease, if oxidized, or in an acidic environment. Therefore, alkalinizing the urine is crucial to prevent the complex from dissociating in the kidneys and causing nephrotoxicity.
Safety & warnings
Contraindications
- Impaired hepatic function (unless secondary to acute arsenic toxicity)
- Iron poisoning
- Cadmium poisoning
- Selenium poisoning
Adverse effects
- Pain at injection site
- Vomiting
- Seizures (at higher dosages)
- Transient increases in blood pressure
- Tachycardia
- Nephrotoxicity
Precautions
Dimercaprol is potentially nephrotoxic; use cautiously in patients with impaired renal function. To protect the kidneys, the urine should be alkalinized to prevent the chelated drug from dissociating in the urine. Animals with diminished renal function or who develop renal dysfunction while on therapy should have the dosage adjusted or therapy discontinued. IM injections must be administered deeply to minimize pain. May decrease Iodine I 131 thyroidal uptake values.
Drug interactions
Forms a highly toxic complex. Do not administer with iron salts; wait at least 24 hours after the last dimercaprol dose before starting iron therapy.
Forms a highly toxic complex. Do not administer with selenium salts; wait at least 24 hours after the last dimercaprol dose before starting selenium therapy.
Forms a highly toxic complex.
Forms a highly toxic complex.
Forms highly toxic complexes
Monitoring
- Liver function
- Renal function
- Hemogram
- Hydration and perfusion status
- Electrolytes and acid/base status
- Urinary pH (maintain alkaline pH)
Pharmacokinetics
Absorption
Peak blood levels occur in 30-60 minutes after IM injection. Slowly absorbed through the skin after topical administration.
Distribution
Distributed throughout the body, including the brain. Highest tissue levels are found in the liver and kidneys.
Metabolism
Non-metal bound drug is rapidly metabolized to inactive compounds.
Elimination
Excreted in the urine, bile, and feces. In humans, completely eliminated within 6-24 hours.
Overdose
Clinical signs of dimercaprol overdosage in animals include vomiting, seizures, tremors, coma, and death. No specific doses were located to correspond with these clinical signs. Treatment should be supportive and symptomatic.
Available products
Formulations
- Injection: 100 mg/mL (10%) in peanut oil and benzyl benzoate
Human-labeled
- Dimercaprol Injection: 100 mg/mL (10%) (for IM use only) in 3 mL ampules (BAL in Oil)
Regulatory status
POM status.
POM (Prescription Only Medicine).
No regulatory data for: 🇺🇸 US · 🇭🇰 HK · 🇹🇼 TW · 🇯🇵 JP · 🇰🇷 KR · 🇦🇺 AU
Storage & stability
Store below 40°C; preferably at room temperature (15-30°C). Unstable in aqueous solutions. The commercially available injection is a peanut oil and benzyl benzoate solution. Turbidity or small amounts of flocculent material/sediment do not indicate deterioration.
Client information
- Strict Supervision Required: Because of the potential toxicity of this agent and the life-threatening nature of heavy metal intoxications, this drug must be used with close professional veterinary supervision, typically in a hospital setting.
- Unusual Odor: Dimercaprol can impart a strong, unpleasant mercaptan-like (garlic or skunk-like) odor to your animal's breath. This is a normal effect of the medication.
- Injection Pain: The medication is given as a deep muscle injection and can be quite painful for your pet.
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.