Vitamin K is a group of vitamins essential for blood clotting, bone health, and preventing heart disease. It plays a crucial role in the formation of specific proteins necessary for these functions. Deficiency can lead to excessive bleeding.
Active Ingredient: Phytonadione
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Side Effects

Vitamin K usually has no side effects. If you have any unusual effects, contact your doctor or pharmacist promptly.

If your doctor has directed you to use this product, remember that your doctor has judged that the benefit to you is greater than the risk of side effects. Many people using this product do not have serious side effects.

A very serious allergic reaction to this drug is rare. However, get medical help right away if you notice any symptoms of a serious allergic reaction, including: rash, itching/swelling (especially of the face/tongue/throat), severe dizziness, trouble breathing.

This is not a complete list of possible side effects. If you notice other effects not listed above, contact your doctor or pharmacist.

In the US – Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088 or at

In Canada – Call your doctor for medical advice about side effects. You may report side effects to Health Canada at 1-866-234-2345.

How long does it take for this medicine to take effect?

The onset of action for vitamin K tablets can vary depending on the individual's baseline vitamin K levels, the specific condition being treated, and the form of vitamin K administered. Improvement in vitamin K deficiency symptoms or in conditions related to vitamin K (such as improvement in blood clotting function) can be observed within a few days to a week of supplementation.

How long do the effects of this medicine last?

Vitamin K is stored in small amounts in the liver and has a relatively short half-life, necessitating regular dietary intake or supplementation to maintain adequate levels. The effects of a single dose can last several days, but consistent daily intake is important for long-term health benefits and maintaining normal physiological functions.

Is it safe to consume alcohol while taking this medicine?

Chronic alcohol consumption can interfere with vitamin K metabolism and liver function, potentially leading to a deficiency. Moderate alcohol consumption may not have a significant impact, but individuals with liver disease or those at risk for vitamin K deficiency should be cautious about alcohol intake and consult with a healthcare provider.

Is this a habit forming medicine?

Vitamin K is not habit-forming and does not have the potential for abuse or dependence. It is an essential nutrient needed for health and well-being, not a psychoactive substance.

Can this medicine be taken during pregnancy?

Vitamin K is considered safe and necessary during pregnancy for normal blood clotting and bone development. The American College of Obstetricians and Gynecologists (ACOG) recommends vitamin K supplementation for pregnant individuals at risk of deficiency to prevent complications. However, excessive amounts should be avoided, and supplementation should be under the guidance of a healthcare provider.

Can this medicine be taken while breast-feeding?

Vitamin K is also safe and important during breastfeeding. It is essential for preventing vitamin K deficiency bleeding (VKDB) in newborns, a rare but serious condition. Newborns are routinely given a vitamin K injection at birth to prevent VKDB. Nursing parents should continue to maintain adequate vitamin K intake to support their health and the health of their breastfed infant, following recommended dietary allowances unless advised otherwise by a healthcare provider.


Vitamin K is used to treat and prevent low levels of certain substances (blood clotting factors) that your body naturally produces. These substances help your blood to thicken and stop bleeding normally (such as after an accidental cut or injury). Low levels of blood clotting factors increase the risk for unusual bleeding. Low levels may be caused by certain medications (such as warfarin) or medical conditions (such as obstructive jaundice). Vitamin K helps to treat and prevent unusual bleeding by increasing the body's production of blood clotting factors.

How to use VITAMIN K

If you are taking the over-the-counter product to self-treat, read all directions on the product package before taking this medication. If you have any questions, consult your pharmacist. If your doctor has prescribed this medication, take it as directed.

If you are using the rapidly-dissolving tablets, place under your tongue to dissolve, then swallow with or without water. Some brands may also be swallowed whole.

The dosage is based on your age, medical condition and response to treatment. Do not increase your dose or use this drug more often or for longer than directed. Your condition will not improve any faster, and your risk of side effects will increase.

If you are using a certain “blood thinner” drug (warfarin), vitamin K can decrease the effects of warfarin for up to 2 weeks. Be sure to take your vitamin K and warfarin exactly as directed by your doctor or pharmacist.

If you develop easy bruising or bleeding, or if you think you may have a serious medical problem, get medical help right away. You may need another dose of vitamin K.


Before taking vitamin K, tell your doctor or pharmacist if you are allergic to it; or if you have any other allergies. This product may contain inactive ingredients, which can cause allergic reactions or other problems. Talk to your pharmacist for more details.

Before using this medication, tell your doctor or pharmacist your medical history, especially of: blood disorders, gallbladder disease (such as obstructive jaundice, biliary fistula), liver disease.

Before having surgery, tell your doctor or dentist about all the products you use (including prescription drugs, nonprescription drugs, and herbal products).

During pregnancy, this product should be used only when clearly needed. Discuss the risks and benefits with your doctor.

Vitamin K passes into breast milk, but is unlikely to harm a nursing infant. Consult your doctor before breast-feeding.


If someone has overdosed and has serious symptoms such as passing out or trouble breathing, call 911. Otherwise, call a poison control center right away. US residents can call their local poison control center at 1-800-222-1222. Canada residents can call a provincial poison control center.

Lab tests (such as prothrombin time, INR) may be done while you are taking this product. Keep all medical and lab appointments. Consult your doctor for more details.

Remember that it is best to get your vitamins and minerals from food whenever possible. Eat a well-balanced diet, and follow any dietary guidelines as directed by your doctor. Foods rich in vitamin K include green leafy vegetables such as spinach, collards, and broccoli.

If you are taking this product on a regular schedule and miss a dose, take it as soon as you remember. If it is near the time of the next dose, skip the missed dose. Take your next dose at the regular time. Do not double the dose to catch up.

Store at room temperature away from light and moisture. Do not store in the bathroom. Keep all medications away from children and pets.

Do not flush medications down the toilet or pour them into a drain unless instructed to do so. Properly discard this product when it is expired or no longer needed. Consult your pharmacist or local waste disposal company.


Drug interactions may change how your medications work or increase your risk for serious side effects. This document does not contain all possible drug interactions. Keep a list of all the products you use (including prescription/nonprescription drugs and herbal products) and share it with your doctor and pharmacist. Do not start, stop, or change the dosage of any medicines without your doctor's approval.

Some products that may interact with this drug include: “blood thinners” (such as acenocoumarol, warfarin).

Avoid taking this medication at the same time as orlistat (a weight-management drug). Wait at least 2 hours between taking this medication and orlistat because taking them together may decrease the effect of vitamin K.

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