Dimercaprol, also called British anti-Lewisite (BAL), is a medication used to treat acute poisoning by arsenic, mercury, gold, and lead. It may also be used for antimony, thallium, or bismuth poisoning, although the evidence for those uses is not very strong. It is given by injection into a muscle.

Common side effects include high blood pressure, pain at the site of the injection, vomiting, and fever. It is not recommended for people with peanut allergies as it is typically formulated as a suspension in peanut oil. It is unclear if use in pregnancy is safe for the baby. Dimercaprol is a chelator and works by binding with heavy metals. It has a very pungent odor.

Dimercaprol was first made during World War II. It is on the World Health Organization's List of Essential Medicines.