Phytonadione is a synthetic vitamin K1. Green leafy vegetables contain the same form naturally. It gives the liver a direct building block to make proteins that help blood clot normally.
You absorb this fat-soluble vitamin best when you take it with a meal that includes fat. Tablets and liquid drops are common oral forms.
Most people tolerate phytonadione fine. Still, avoid high or unnecessary doses. Talk to a doctor before starting any new supplement.