Several vitamins can be dangerous when you take too much of them, but for most people, vitamin K isn't one of them. The only people who could get too much vitamin K are those taking the blood-thinning medication warfarin.

If you decide you want to increase or decrease your vitamin K intake, it's important to discuss with your doctor the best way to do that, as your dosage may need adjusting either up or down.

If you're taking warfarin, you likely get regular blood tests to determine its efficacy. Your lab results will provide your prothrombin time (PT) and international normalized ratio (INR) values. Your INR values should stay in a safe range; if they are too high or too low, it may be because of the interaction between warfarin and vitamin K.

Vitamin K functions to lower your INR values, which means that warfarin may not be effective for preventing a blood clot. Warfarin increases your INR values, which slows blood clotting. If warfarin is too effective, you will bleed more easily and quickly, which can be dangerous.