[Durgical](https://durgical.com/en/) › [DurgiPedia](https://durgical.com/en/durgipedia/) › [Pharmacology](https://durgical.com/en/pharmacology/) › [Chelating agents](https://durgical.com/en/pharmacology/classes/chelating-agents/) › Dimercaprol

[Pharmacology](https://durgical.com/en/pharmacology/) · [Chelating agents](https://durgical.com/en/pharmacology/classes/chelating-agents/)

# Dimercaprol

An intramuscular chelator with two sulfhydryl groups that binds arsenic, mercury and lead. In lead encephalopathy it is given before edetate.

Updated 2026-11-01

- Class: [Chelating agents](https://durgical.com/en/pharmacology/classes/chelating-agents/)
- Target: Heavy-metal ions (arsenic, mercury, lead)
- ATC code: V03AB09
- WHO Model List of Essential Medicines

Also called: British anti-Lewisite (BAL), 2,3-dimercaptopropanol

## Mechanism of action

Arsenic, mercury and lead poison cells by binding the sulfhydryl (-SH) groups of enzymes. Dimercaprol has two -SH groups that bind these metals more strongly, preventing or reversing their binding to enzymes. The dimercaprol–metal complex is excreted in urine; it breaks apart in acidic urine, so urine is kept alkaline to protect the kidney. With iron the complex is more toxic than the metal.

- Metals block the -SH groups of enzymes
- Dimercaprol's two -SH groups grab the metal
- Enzymes are freed
- The complex leaves in alkaline urine

## Pharmacokinetics

**Absorption**
Given only by deep intramuscular injection

**Elimination**
As metal complexes in urine

## Indications

- Arsenic poisoning [Arsenic poisoning →](https://durgical.com/en/conditions/arsenic-poisoning/)
- Elemental and some inorganic mercury poisoning; not for organic (methyl) mercury [Mercury poisoning →](https://durgical.com/en/conditions/mercury-poisoning/)
- Severe lead poisoning and lead encephalopathy, together with edetate calcium disodium [Lead poisoning →](https://durgical.com/en/conditions/lead-poisoning/)

## Adverse effects

### Common

- Intense pain at the injection site
- Nausea, vomiting and headache
- Burning of the lips, mouth and throat; salivation and tearing
- Muscle aches and tingling of the limbs

### Serious (rare, important)

- Haemolysis in G6PD deficiency
- Kidney injury if the complex dissociates or iron is given at the same time
- Allergic reactions in people allergic to peanuts

## Contraindications

- Peanut allergy
- Liver failure
- Methylmercury (organic mercury) poisoning
- Iron poisoning, and concurrent iron therapy

## Key interactions

**Iron supplements**
The dimercaprol–iron complex is toxic and increases the risk of kidney injury; they are not combined

## What is monitored

- Urine pH and output
- Kidney and liver function
- Blood or urine metal levels
- Haemoglobin if G6PD deficiency is possible

## Administration and safety

- Deep intramuscular injection only; never intravenous
- In lead encephalopathy the first dimercaprol dose comes before edetate is started

## Nursing care

- Ask about peanut allergy before the first injection
- Check urine pH and keep the patient well hydrated
- Assess injection sites and pain
- Look for the source of exposure (work, home, traditional remedies)

## Pregnancy and breastfeeding

Animal and human data are limited (category C in the Colombian guide); it is used when clearly needed, and breastfeeding is avoided.

## Memory aid

Dimercaprol: «two hooks» (-SH) for AML: Arsenic, Mercury (inorganic) and Lead, in the muscle only, and never with iron.

## Test yourself

Think of the answer, then tap the question to see it.

## Why is urine kept alkaline during dimercaprol treatment?

The dimercaprol–metal complex dissociates in acid urine and the freed metal injures the kidney.

## Why is dimercaprol not used for iron poisoning?

The dimercaprol–iron complex is more toxic than iron, especially to the kidney.

## Which allergy must be asked about before giving dimercaprol?

Peanut allergy.

[Add to my cards (3)](https://durgical.app/estudiar/?add=/en/pharmacology/dimercaprol/)

## Related conditions

- [Arsenic poisoning](https://durgical.com/en/conditions/arsenic-poisoning/)
- [Mercury poisoning](https://durgical.com/en/conditions/mercury-poisoning/)
- [Lead poisoning](https://durgical.com/en/conditions/lead-poisoning/)

[← Back to the class: Chelating agents](https://durgical.com/en/pharmacology/classes/chelating-agents/)

Educational content on how drugs work; not a prescribing guide and no substitute for a health professional's advice. No doses are given.

Sources: [Guía para el Manejo de Emergencias Toxicológicas](https://minsalud.gov.co/sites/rid/Lists/BibliotecaDigital/RIDE/DE/GT/guias-manejo-emergencias-toxicologicas-outpout.pdf) (Ministerio de Salud y Protección Social; Organización Panamericana de la Salud, 2017); [eEML - Electronic Essential Medicines List](https://list.essentialmeds.org/) (World Health Organization, 2025); [ATCDDD - ATC/DDD Index](https://atcddd.fhi.no/atc_ddd_index/?code=V03AB09) (WHO Collaborating Centre for Drug Statistics Methodology, 2026).

## **Spotted a mistake?** We are always improving for the community. Tell us what is wrong and our team will review it. Report a mistake

Representative model, for educational purposes only.

---
Source: https://durgical.com/en/pharmacology/dimercaprol/
License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/pharmacology/dimercaprol/