Nov132025
Vitamin K’ written in chalk on slate, surrounded by various food sources of the vitamin.

Can anyone take vitamin K?

Vitamins are often thought of as universally safe additions to the diet, but that doesn’t mean all vitamins are the right choice for all people at all times. 

Vitamin K is a good example of this. While it plays an essential role in blood clotting and bone health, there are circumstances where extra care is needed before starting supplementation.1 For this reason, it’s always best to seek professional advice if you’re considering adding vitamin K – or any other supplement – to your daily routine.

Below, we’ll explore some specific situations where taking vitamin K may require more thought.

Can I take vitamin K during my period?

For most people, menstruation does not affect whether vitamin K supplements can be taken. Vitamin K supports normal blood clotting, which might sound concerning during a period, but having healthy clotting function is part of the body’s normal balance.2 

If your periods are particularly heavy, it may be worth discussing with a healthcare professional whether vitamin K or other nutrients could play a role in your overall health.3 However, in general, taking vitamin K during menstruation does not pose additional risks.

Can I take vitamin K while breastfeeding?

Breastfeeding is a time when many parents consider supplements to help ensure both their own health and that of their baby. 

Vitamin K can usually be taken while breastfeeding, but it’s important to note that newborns themselves are typically given a vitamin K injection shortly after birth.4 This is because babies are born with naturally low vitamin K levels, and supplementation helps reduce the risk of bleeding issues in early life.5

For breastfeeding parents, the decision to take vitamin K should always be guided by a doctor or midwife. While it’s generally safe, the right approach may depend on your diet, medical history and whether your baby has already received their vitamin K shot.

Can I take vitamin K while pregnant?

During pregnancy, every supplement should be chosen carefully. 

Vitamin K is essential for blood clotting and bone development, but in most cases, people can meet their needs through a balanced diet rather than supplementation.6 If you are pregnant and thinking about taking vitamin K, it’s especially important to seek medical guidance first.

Doctors may recommend additional vitamin K in rare situations, such as if there is a diagnosed deficiency, but routine supplementation during pregnancy is not typically necessary for everyone.7 Professional advice ensures both you and your baby get what you need without unnecessary risks.

Can I take vitamin K with blood thinners?

This is perhaps the most important situation to highlight. Vitamin K plays a key role in the blood clotting process, which means it can interact with blood-thinning medications such as warfarin.⁸ Taking vitamin K supplements while using these medications can make them less effective, as vitamin K may work against their purpose of preventing clots.9

For people who are prescribed blood thinners to manage or prevent conditions such as deep vein thrombosis or pulmonary embolism, this interaction can have significant consequences. If vitamin K levels increase unexpectedly, it could reduce the effectiveness of these medications and raise the risk of developing unwanted blood clots. These clots can sometimes cause symptoms such as swelling, pain, or shortness of breath, which may require urgent medical attention. This does not mean that vitamin K should be completely avoided, but it does highlight how important it is to manage intake carefully.

If you are prescribed blood thinners, you should not start vitamin K supplements without medical supervision. In some cases, doctors will ask patients to keep their vitamin K intake consistent from diet and supplements, but the exact balance must be monitored closely. This is why professional advice is critical in this scenario.

 

Vitamin K is a vital nutrient that helps support clotting and bone health, but supplementation isn’t a one-size-fits-all solution. For most healthy adults, moderate intake from food sources is usually enough. However, if you are pregnant, breastfeeding, experiencing heavy periods or taking blood-thinning medication, speaking to a healthcare professional is strongly advised before starting supplements.

 

References

  1. National Institutes of Health. (2022). Vitamin K Fact Sheet for Health Professionals. https://ods.od.nih.gov/factsheets/VitaminK-HealthProfessional/
  2. Shearer, M. J., & Newman, P. (2014). Metabolism and cell biology of vitamin K. Thrombosis and Haemostasis, 111(4), 539–547. https://doi.org/10.1160/TH13-08-0639
  3. Pavlovic, M., & Danilovic, D. (2019). The role of vitamin K in women’s health. Journal of Women’s Health Care, 8(5). https://doi.org/10.35248/2167-0420.19.8.489
  4. Institute of Medicine. (2001). Dietary Reference Intakes for Vitamin A, Vitamin K, Arsenic, Boron, Chromium, Copper, Iodine, Iron, Manganese, Molybdenum, Nickel, Silicon, Vanadium, and Zinc. Washington, DC: The National Academies Press.
  5. McNinch, A., & Tripp, J. H. (1991). Haemorrhagic disease of the newborn in the British Isles: Two year prospective study. BMJ, 303(6810), 1105–1109. https://doi.org/10.1136/bmj.303.6810.1105
  6. Booth, S. L. (2012). Vitamin K: Food composition and dietary intakes. Food & Nutrition Research, 56(1), 5505. https://doi.org/10.3402/fnr.v56i0.5505
  7. Greer, F. R. (1999). Vitamin K status of lactating mothers and their infants. Acta Paediatrica, 88(s430), 95–103. https://doi.org/10.1111/j.1651-2227.1999.tb01305.x
  8. Stafford, D. W. (2005). The vitamin K cycle. Journal of Thrombosis and Haemostasis, 3(8), 1873–1878. https://doi.org/10.1111/j.1538-7836.2005.01419.x
  9. Hirsh, J., Fuster, V., Ansell, J., & Halperin, J. L. (2003). American Heart Association/American College of Cardiology Foundation guide to warfarin therapy. Circulation, 107(12), 1692–1711. https://doi.org/10.1161/01.CIR.0000063575.17904.4E