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No tolerable upper intake level (UL) has been set for vitamin K. The National Academies found too little data to set one for vitamin K. Health Canada, which uses the same values, adds that this "does not mean that there is no potential for adverse effects resulting from high intakes." That doesn’t make any amount safe for everyone: talk to your doctor about high doses.
Take several supplements? Add them all up in the Supplement Checker: it shows your vitamin K total next to the nutrients that do have a limit.
How much Vitamin K you need
| Age | Males | Females | Pregnancy | Breastfeeding |
|---|---|---|---|---|
| Birth to 6 months | 2 mcg* | 2 mcg* | – | – |
| 7-12 months | 2.5 mcg* | 2.5 mcg* | – | – |
| 1-3 years | 30 mcg* | 30 mcg* | – | – |
| 4-8 years | 55 mcg* | 55 mcg* | – | – |
| 9-13 years | 60 mcg* | 60 mcg* | – | – |
| 14-18 years | 75 mcg* | 75 mcg* | 75 mcg* | 75 mcg* |
| 19-30 years | 120 mcg* | 90 mcg* | 90 mcg* | 90 mcg* |
| 31-50 years | 120 mcg* | 90 mcg* | 90 mcg* | 90 mcg* |
| 51-70 years | 120 mcg* | 90 mcg* | – | – |
| 71+ years | 120 mcg* | 90 mcg* | – | – |
* Adequate Intake (AI): the amount set when there isn’t enough evidence for an RDA.
What counts toward the Vitamin K limit
No upper limit (UL) has been set for vitamin K.
What happens with too much Vitamin K
No UL exists. The National Academies (IOM 2001) say no adverse effects from vitamin K in food or supplements have been reported in humans or animals, but that "alterations in vitamin K intake can, therefore, influence warfarin efficacy." Health Canada says the missing UL "does not mean that there is no potential for adverse effects resulting from high intakes", and its warfarin page says vitamin K "is known to decrease the effects of warfarin."
Sources: National Academies, Dietary Reference Intakes for Calcium and Vitamin D (2011); Health Canada, Dietary Reference Intakes tables (the joint U.S.-Canada values); National Academies, Dietary Reference Intakes for Vitamin A, Vitamin K, Arsenic, Boron, Chromium, Copper, Iodine, Iron, Manganese, Molybdenum, Nickel, Silicon, Vanadium, and Zinc (2001). Limits checked November 8, 2026. More from the NIH: Office of Dietary Supplements Vitamin K fact sheet.
If you think you or a child took too much of a supplement, call Poison Control at 1-800-222-1222 (U.S., free, 24 hours) or use poison.org. In an emergency, call 911.
General information, not medical advice. Your doctor may recommend a different amount, for example to treat a deficiency. Talk to your doctor or pharmacist before you start, stop or change a supplement, especially if you are pregnant, nursing, take medication or have a medical condition.