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Generic Name: phytonadione (fye toe na DYE own)
Brand Name: Mephyton, Vitamin K1

Medically reviewed: July 28, 2017

What is Mephyton?

Mephyton is a man-made form of vitamin K, which occurs naturally in the body.

Mephyton is used to treat vitamin K deficiency and to treat certain bleeding or blood clotting problems.

Mephyton may also be used for purposes not listed in this medication guide.

Important Information

Before using Mephyton tell your doctor about all your medical conditions or allergies, all medicines you use, and if you are pregnant or breast-feeding.

Never take Mephyton in larger amounts, or for longer than recommended by your doctor.

Before taking this medicine

You should not be treated with Mephyton if you are allergic to it.

Before you receive Mephyton, tell your doctor about all your medical conditions or allergies.

To make sure you can safely take Mephyton, tell your doctor if you have liver disease.

It is not known whether this medicine will harm an unborn baby. Tell your doctor if you are pregnant or plan to become pregnant.

It is not known whether Mephyton passes into breast milk or if it could affect the nursing baby. Tell your doctor if you are breast-feeding.

How should I use Mephyton?

Follow all directions on your prescription label. Your doctor may occasionally change your dose. Never take this medicine in larger amounts, or for longer than prescribed.

Do not give a injection to a child without medical advice. Injectable Mephyton contains an ingredient that can cause serious side effects or death in very young infants or premature babies. Do not allow an older child to use this medicine without supervision of an adult.

While using Mephyton, you may need frequent blood tests.

If you need surgery or dental work, tell the surgeon or dentist ahead of time that you are using Mephyton.

Store at room temperature away from moisture and heat. Protect from light. Keep the medicine in the original container and tightly closed when not in use.

What happens if I miss a dose?

Call your doctor for instructions if you miss a dose of Mephyton.

What happens if I overdose?

Seek emergency medical attention or call the Poison Help line at 1-800-222-1222.

What should I avoid while taking Mephyton?

Follow your doctor's instructions about any restrictions on food, beverages, or activity.

Mephyton side effects

Get emergency medical help if you have signs of an allergic reaction: hives; difficult breathing; swelling of your face, lips, tongue, or throat.

Call your doctor at once if you have:

  • a light-headed feeling, like you might pass out;

  • blue colored lips;

  • trouble breathing;

  • weak but rapid pulse; or

  • skin redness, itching, or a hard lump where an injection was given.

Common side effects may include:

  • dizziness;

  • flushing (warmth, redness, or tingly feeling);

  • changes in your sense of taste;

  • sweating; or

  • pain or swelling where the medicine was injected.

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.

See also: Side effects (in more detail)

What other drugs will affect Mephyton?

Tell your doctor about all your current medicines and any you start or stop using, especially:

This list is not complete. Other drugs may interact with phytonadione, including prescription and over-the-counter medicines, vitamins, and herbal products. Not all possible interactions are listed in this medication guide.

Further information

Remember, keep this and all other medicines out of the reach of children, never share your medicines with others, and use this medication only for the indication prescribed.

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.

Medical Disclaimer