Major Uses

Phytonadione is another name for Vitamin K1. This vitamin is primarily used in the treatment of animals poisoned with rat poison. It is sometimes used for other conditions.

Phytonadione is a coagulant that prevents excessive internal bleeding caused by the anticoagulant in rat and mouse poisons. Vitamin K1 is needed by the body to produce certain blood clotting factors in the liver, and rat poisons work by preventing the body from using its own stores of vitamin K1 so that the poisoned animal bleeds to death. Phytonadione provides additional K1 to correct the deficiency and stop the bleeding.

Common Precautions

The most common side effects of phytonadione are pain, swelling, and tenderness at the site of injection. Overall, side effects are very rare with proper use of this medication.

Intravenous administration of phytonadione may cause death and should never be used. Intramuscular injections may cause bleeding during early treatment.

Dehydrated animals may have difficulty absorbing subcutaneous and oral doses. Rehydration is necessary. This medication is not for use in nursing or pregnant animals. Bleeding disorders caused by liver damage or heparin administration are not correctable with phytonadione. Pets undergoing treatment with phytonadione should be monitored for bleeding and bruising during and after use. Pets should be kept quiet during and for at least one week after treatment.

Some drugs may decrease the action of phytonadione and increase the action of the poison's anticoagulant properties, including anabolic steroids, aspirin, phenylbutazone, sulfonamides, cimetidine, chloramphenicol, diazoxide, erythromycin, metronidazole, ketoconazole, thyroid drugs, and propanolol. Phytonadione absorption may be decreased by mineral oil, and the effects of coumarin are decreased with phytonadione use.

Phytonadione should not be used in animals with a known allergy or hypersensitivity to the drug. Overdose of phytonadione is not likely to cause symptoms. Still, any known or suspected overdose of phytonadione should be reported to a veterinarian right away.


Phytonadione should be stored at room temperature, in a tightly sealed and light-resistant container. It should be kept out of the reach of children and animals. It should not be stored in the bathroom or above the kitchen sink, and it should be kept away from direct sunlight and heat sources.


Phytonadione is available as a tablet, capsule, and injectable solution.

Phytonadione is typically given by injection for the first dose, and then given orally for several weeks thereafter. The initial loading dose of the medication is generally 1.15 to 2.25 mg/lb by subcutaneous injection, divided over several sites. Oral doses are typically 2.5 mg/lb daily, divided into several doses over the course of a day. This medication should be given just before or with foods high in fat content.

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 phytonadione is missed, it should be given as soon as possible. If it is almost time for the next dose, the missed dose should be skipped and the regular schedule resumed. Two doses of this medication should not be given at the same time.

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.