Healthdirect Free Australian health advice you can count on.

Medical problem? Call 1800 022 222. If you need urgent medical help, call triple zero immediately

healthdirect Australia is a free service where you can talk to a nurse or doctor who can help you know what to do.

beginning of content

Vitamin K deficiency

5-minute read

Key facts

  • Vitamin K is important because it helps the liver make proteins that allow blood to clot.
  • Vitamin K deficiency is rare — adults usually have enough vitamin K because normal bacteria in the gut produce it, and it is also in the fat of many commonly available foods.
  • Not having enough vitamin K in the body can make you bruise or bleed more easily than usual.
  • A blood test can confirm vitamin K deficiency.
  • If you are deficient in vitamin K, your doctor will prescribe vitamin K supplements.

Why is vitamin K important?

Vitamin K is important because it helps the liver make proteins that allow your blood to clot normally, to prevent excessive bleeding. It is also important for healthy bones.

Adults usually have enough vitamin K, because normal bacteria in the gut produce it. It is also in the fat of much of the food that we eat. Vitamin K gets stored in the liver, so you don’t need to eat it every day, unlike some other vitamins.

See this article for important information on babies and vitamin K.

What are the symptoms of vitamin K deficiency?

Not having enough vitamin K in the body makes you more likely to bleed. You may bruise more easily than usual, or it may be more difficult to stop bleeding after an injury or surgery.

It can also make your periods heavier.

What causes vitamin K deficiency?

Vitamin K deficiency in healthy adults is rare. Most adults with vitamin K deficiency have a serious health problem such as:

People taking antibiotics for long periods of time are also more likely to develop vitamin K deficiency.

How is vitamin K deficiency diagnosed?

If your doctor suspects you have vitamin K deficiency, they will refer you for a blood test to confirm it.

  • Some pathology services and hospitals measure vitamin K levels directly.
  • If that is not possible, you can have a blood test to check how well your blood clots. Your clotting can be checked again after an injection of vitamin K. If your clotting improves after the injection, this is evidence that you have vitamin K deficiency.

How is vitamin K deficiency treated?

If you have vitamin K deficiency, your doctor will prescribe vitamin K supplements. They can help your blood clot normally, and they might help increase bone strength. Only take vitamin K supplements after talking to your doctor first, since they can interfere with some other medicines. Only take the amount of vitamin K that your doctor recommends — larger doses might be harmful.

If you do not have enough vitamin K, it can also help to eat more of the foods listed below. It may be useful for you to see a dietitian.

How is vitamin K deficiency prevented?

While bacteria in your gut produce some of the vitamin K your body needs, you also consume vitamin K from commonly available foods. The best dietary sources of vitamin K are dark green leafy vegetables like spinach, parsley, broccoli, kale, cabbage, brussel sprouts and salad greens.

Green beans, avocados, kiwifruit, vegetable oils (especially soybean and canola oils), yoghurt, fermented food and drinks and some cheeses are also good sources. Eating these foods can help you prevent vitamin K deficiency.

When should I see my doctor?

You should see your doctor if you bruise easily or have bleeding sores or scabs that don’t heal. This could be a sign of vitamin K deficiency.

FIND A HEALTH SERVICE — The Service Finder can help you find doctors, pharmacies, hospitals and other health services.

ASK YOUR DOCTOR — Preparing for an appointment? Use the Question Builder for general tips on what to ask your GP or specialist.

Learn more here about the development and quality assurance of healthdirect content.

Last reviewed: October 2022


Back To Top

Need more information?

These trusted information partners have more on this topic.

Top results

Vitamin K for newborns | NHMRC

Vitamin K helps blood to clot and is essential in preventing serious bleeding in infants. Vitamin K deficiency bleeding can be prevented by the administration of vitamin K soon after birth. By the age of approximately six months, infants have built up their own supply of vitamin K.

Read more on NHMRC – National Health and Medical Research Council website

Vitamin K at birth

Parents of all newborn babies are offered a vitamin K injection for their baby soon after birth. Find out why vitamin K is important for your baby.

Read more on Pregnancy, Birth & Baby website

Vitamin K and newborn babies - Better Health Channel

With low levels of vitamin K, some babies can have severe bleeding into the brain, causing significant brain damage.

Read more on Better Health Channel website

Factor II deficiency - Haemophilia Foundation Australia

Brief introductory information about factor II (2) deficiency, also known as prothrombin deficiency, and links to more detailed high quality information.

Read more on Haemophilia Foundation Australia website

Protein C and S | Pathology Tests Explained

Proteins C and S help adjust the rate of blood clot formation. When a blood vessel or tissue is injured, the body initiates the coagulation cascade - a step

Read more on Pathology Tests Explained website

Coagulation factors | Pathology Tests Explained

Coagulation factors are proteins that are essential for blood clot formation. Produced by the liver or blood vessels, the coagulation factors are continuousl

Read more on Pathology Tests Explained website

International normalised ratio (INR) | Pathology Tests Explained

The test measures how long it takes for your blood to begin to form clots. Prothrombin is a plasma protein produced by the liver. Clotting is caused by a ser

Read more on Pathology Tests Explained website

Hepatitis B | Sharing Knowledge About Immunisation | SKAI

Hepatitis B Key facts Your baby is most at risk of catching hepatitis B infection at birth

Read more on National Centre for Immunisation Research and Surveillance (NCIRS) website

Baby's first 24 hours

There is a lot going on in the first 24 hours of your baby's life. Find out what you can expect and how to help them adjust to life outside the womb.

Read more on Pregnancy, Birth & Baby website

Activated partial thromboplastin time | Pathology Tests Explained

The activated partial thromboplastin time (APTT or PTT) is a functional measure of the intrinsic and common pathways of the coagulation cascade. When blood v

Read more on Pathology Tests Explained website

Healthdirect 24hr 7 days a week hotline

24 hour health advice you can count on

1800 022 222

Government Accredited with over 140 information partners

We are a government-funded service, providing quality, approved health information and advice

Australian Government, health department logo ACT Government logo New South Wales government, health department logo Northen Territory Government logo Queensland Government logo Government of South Australia, health department logo Tasmanian government logo Victorian government logo Government of Western Australia, health department logo

Healthdirect Australia acknowledges the Traditional Owners of Country throughout Australia and their continuing connection to land, sea and community. We pay our respects to the Traditional Owners and to Elders both past and present.