Major Uses

Penicillamine is a chelating agent. It treats illness or injury resulting from heavy metal poisoning by removing the copper, iron, lead, or other metal from the body. Penicillamine is a byproduct of penicillin, which is a common antibiotic; however, this drug does not have antibiotic properties.

Penicillamine is most commonly used in dogs and cats to treat liver disease caused by copper accumulation. It is also often used to treat lead poisoning and bladder and kidney stones. It is not approved by the Food and Drug Administration for use in animals, but it is prescribed legally as an extra-label drug by veterinarians.

Common Precautions

Nausea and vomiting are the two most common side effects associated with proper use of penicillamine. Kidney impairment, fever, blood disorders, and skin reactions have also been reported.

Penicillamine is not for use during pregnancy. Birth defects can occur when this drug is administered to pregnant animals. Penicillamine is known to interact with a number of other supplements and medications, including azathoprine, certain antacids, and cyclophosphamide.

Penicillamine should not be used in animals with a known allergy or hypersensitivity to the drug. Any known or suspected overdose should be reported to a veterinarian right away.


Penicillamine should be stored in a tightly-sealed container, at room temperature, and out of the reach of children and pets. This drug should not be used after its expiration date.


Penicillamine is available as tablets or capsules in various strengths. Animals undergoing treatment for lead poisoning are typically given a dose of 15 to 50 mg/lb (30 to 110 mg/kg) per day. The total amount is divided into several doses over the course of the day. Treatment may last weeks to months.

This drug should be given on an empty stomach, when possible. Doses may vary in different species, when the drug is given by a different route or concurrently with other medications, and with regards to a patient's age, breed, and health status. A veterinarian's dosing instructions and/or those printed on the medication label should be followed closely.

If a dose of this medication is missed, it should be taken as soon as possible. If it is almost time for the next dose, the missed dose should be skipped and the normal schedule should be resumed. Dosing should be closely monitored by a veterinarian.

This information is for general reference only and should not be used for the diagnosis or treatment of any condition of your pet. It's intended as a general reference, this information may not include all possible uses, precautions, directions, reactions (including allergic), drug interactions, or withdrawal times. Always consult your local veterinarian and have your pet examined for any advice concerning the diagnosis and treatment of your pet, including which products and doses are most appropriate. Any trademarks are the property of their respective owners. VetDepot is not a pharmacy. All prescription products are dispensed by our Pharmacy Partner. Article last updated 2/2014.