Since garlic does not contain any vitamin K whatsoever, it should not be a problem for those who are already on Warfarin or Coumadin as it is also known. Many people worry about they will experience an adverse reaction from their medication by eating a certain type of food, though garlic can be eaten while on this particular medication.
Since parsley for example in very high in vitamin K, it can potentially cause adverse interactions with Warfarin and should therefore not be ingested while on this medication. It is very important for those who are on powerful medications like Warfarin to know which foods are acceptable to eat and which to stay away from.