What is phytonadione?
Phytonadione, also called vitamin K1 (brand names: Mephyton®, Phytomenadione®, Aqua-Mephyton®, K-Caps®, Konakion®, Hemophyt®) is a vitamin supplement that is used as an antidote to anticoagulant rodenticide, sweet clover, dicumarol, or sulfaquinoxaline toxicities. It is also used to treat bleeding disorders caused by conditions such as liver failure. It is used in cats, dogs, horses, birds, and rabbits.
The U.S. Food and Drug Administration (FDA) does not review non-drug health products (e.g., herbals, nutraceuticals, shampoos, and other supplements) for safety or effectiveness before they are sold to the public. Manufacturers of non-drug health products must ensure their products are safe and labeled accurately.
The FDA requires that these non-pharmaceuticals contain a disclaimer that says, “This product is not intended to diagnose, treat, cure or prevent any disease.” Health Canada licenses “veterinary health products” after reviewing safety, efficacy, and manufacturing information provided by the manufacturer. These products are not tested by Health Canada.
Your veterinarian is the best source of information about the safety of non-drug health products in pets. Just because a product is natural does not mean it is safe. All medicines and medicinal plants are potentially toxic if used inappropriately or given at high doses.
Supplements can also have side effects, like pharmaceuticals. Few supplements and herbs have been subjected to rigorous scientific trials to determine their efficacy.
Although the information in this handout may be helpful, it also may be incomplete and may not represent the full range of effects the supplement could have on your pet.
How is phytonadione given?
- Phytonadione comes in capsule, liquid, powder, or chewable tablet forms. An injectable form is available that your veterinarian can give in hospital.
- All non-injectable forms are given orally (by mouth).
- Give with food, ideally a fatty meal.
- Measure liquid forms carefully.
- Follow your veterinarian’s instructions on administering this supplement and give for the entire time prescribed by your veterinarian, even if your pet is feeling better.
This supplement should take effect within 1 to 2 hours; however, effects may not be noted outwardly, and laboratory tests may be required to evaluate this supplement’s effectiveness.
What if I miss giving my pet the supplement?
If you miss a dose, give it when you remember. However, if it is almost time for the next scheduled dose, give both doses at the same time, and then return to the regular dosing schedule. Do not skip doses.
Are there any potential side effects?
Side effects are uncommon and this vitamin is generally well tolerated when given by mouth.
Serious adverse reactions may occur. If any of the following signs develop, stop giving phytonadione and contact your veterinarian immediately:
- An allergic reaction such as irregular breathing, rash, fever, puffiness and swelling around the face
Sensitivities can develop over time with repeated exposure. Your pet may have no reaction after the first few doses, but may develop a sensitivity later. It is important to watch for signs of an allergic reaction over the entire course of treatment and notify your veterinarian if you have any concerns.
Other side effects may occur. If you notice anything unusual, contact your veterinarian immediately. This short-acting supplement should stop working within 24 hours, although effects can be longer in pets with liver or kidney disease.
Are there any risk factors for this supplement?
DO NOT USE in:
- Pets that are allergic to any component
USE WITH CAUTION in:
- Pets that are pregnant or nursing
Are there any drug interactions I should be aware of?
Several medications should be used with caution when given with phytonadione:
- Mineral oil
- Oral antibiotics
- Warfarin and other blood thinners
Is any monitoring needed with this supplement?
- Clotting tests should be monitored in cases of anticoagulant poisoning, as this is how to evaluate when your pet can discontinue supplementation.
- Your veterinarian will let you know when and how they want to reassess your pet to ensure the supplement is working and not causing side effects.
- At home, monitor for abnormal changes. If any occur, discontinue the supplement and contact your veterinarian.
How do I store phytonadione?
- Store the product at room temperature between 59°F and 86°F (15°C and 30°C).
- Protect from light.
- Follow manufacturer’s instructions for liquid products.
- Keep the container out of reach of children and pets.
What should I do in case of emergency?
If you suspect an overdose or an adverse reaction to the supplement, call your veterinary office immediately. If they are not available, follow their directions in contacting an emergency facility. Be prepared to provide information about the product and your pet's weight and symptoms. Report any adverse effects to the FDA or Health Canada.
