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Mephyton Side Effects

Generic Name: phytonadione

Note: This page contains information about the side effects of phytonadione. Some of the dosage forms included on this document may not apply to the brand name Mephyton.

For the Consumer

Applies to phytonadione: capsule, tablet

In addition to its needed effects, some unwanted effects may be caused by phytonadione (the active ingredient contained in Mephyton). In the event that any of these side effects do occur, they may require medical attention.

Severity: Moderate

If any of the following side effects occur while taking phytonadione, check with your doctor or nurse as soon as possible:

Less common: - With menadiol or high doses of phytonadione in newborns
  • Decreased appetite
  • decreased movement or activity
  • difficulty in breathing
  • enlarged liver
  • general body swelling
  • irritability
  • muscle stiffness
  • paleness
  • yellow eyes or skin
Rare - With injection only
  • Difficulty in swallowing
  • fast or irregular breathing
  • lightheadedness or fainting
  • shortness of breath
  • skin rash, hives and/or itching
  • swelling of eyelids, face, or lips
  • tightness in chest
  • troubled breathing and/or wheezing
  • Blue color or flushing or redness of skin
  • dizziness
  • fast and/or weak heartbeat
  • increased sweating
  • low blood pressure (temporary)

Minor Side Effects

Some of the side effects that can occur with phytonadione may not need medical attention. As your body adjusts to the medicine during treatment these side effects may go away. Your health care professional may also be able to tell you about ways to reduce or prevent some of these side effects. If any of the following side effects continue, are bothersome or if you have any questions about them, check with your health care professional:

Less common:
  • Flushing of face
  • redness, pain, or swelling at place of injection
  • skin lesions at place of injection (rare)
  • unusual taste

For Healthcare Professionals

Applies to phytonadione: compounding powder, injectable solution, oral tablet


Rare (less than 0.1%): Injection site reactions (inflammation, atrophy, necrosis)
Very rare (less than 0.01%): Venous irritation or phlebitis (IV route)
Frequency not reported: Pain, swelling, and tenderness at the injection site[Ref]


Rare (less than 0.1%): Rapid and weak pulse, brief hypotension, cyanosis
Very rare (less than 0.01%): Facial flushing[Ref]


Very rare (less than 0.01%): Anaphylactoid reactions (IV route)
Frequency not reported: Allergic sensitivity, anaphylaxis[Ref]

Fatalities and other severe reactions have occurred during or immediately after the parenteral administration of phytonadione. The majority of these reactions have occurred with intravenous administration. These reactions resemble hypersensitivity or anaphylaxis and include shock and cardiac or respiratory arrest. Feelings of uneasiness, flushing, diaphoresis, chest pain, tachycardia, cyanosis, weakness, and dyspnea may precede the cardiopulmonary event. These severe reactions are more likely with, but are not limited to, rapid infusions of undiluted drug.[Ref]


Gastrointestinal side effects have rarely included 'peculiar' sensations of taste.


Rare (less than 0.1%): Dyspnea[Ref]


Frequency not reported: Death (IV and IM routes)[Ref]


Uncommon (0.1% to 1%): Erythematous, indurated, pruritic plaques
Rare (less than 0.1%): Profuse sweating, scleroderma-like lesions,
Very rare (less than 0.01%): Sweating
Frequency not reported: Erythema perstans-like lesions[Ref]

Nervous system

Rare (less than 0.1%): Dizziness
Very rare (less than 0.01%): Unusual taste[Ref]


Hyperbilirubinemia occurred primarily with doses above those recommended.[Ref]

Rare (less than 0.1%): Hyperbilirubinemia in newborns
Frequency not reported: Jaundice in newborns[Ref]


Frequency not reported: Hemolysis in newborns[Ref]


The most common adverse events were dermatologic and injection site reactions.[Ref]


1. Cerner Multum, Inc. "Australian Product Information." O 0

2. Cerner Multum, Inc. "UK Summary of Product Characteristics." O 0

3. "Product Information. Vitamin K Injection (phytonadione)." Abbott Pharmaceutical, Abbott Park, IL.

4. "Product Information. Mephyton (phytonadione)." Merck & Co, Inc, West Point, PA.

Not all side effects for Mephyton may be reported. You should always consult a doctor or healthcare professional for medical advice. Side effects can be reported to the FDA here.

Disclaimer: Every effort has been made to ensure that the information provided is accurate, up-to-date and complete, but no guarantee is made to that effect. In addition, the drug information contained herein may be time sensitive and should not be utilized as a reference resource beyond the date hereof. This material does not endorse drugs, diagnose patients, or recommend therapy. This information is a reference resource designed as supplement to, and not a substitute for, the expertise, skill , knowledge, and judgement of healthcare practitioners in patient care. The absence of a warning for a given drug or combination thereof in no way should be construed to indicate safety, effectiveness, or appropriateness for any given patient. does not assume any responsibility for any aspect of healthcare administered with the aid of materials provided. The information contained herein is not intended to cover all possible uses, directions, precautions, warnings, drug interactions, allergic reactions, or adverse effects. If you have questions about the substances you are taking, check with your doctor, nurse, or pharmacist.