Blood is something that keeps people alive. Lady Macbeth is like blood to Macbeth and vice versa. Blood is also a symbol of power and strength. Macbeth and Lady Macbeth were the power couple of the play. When LMB was sleep walking, she was trying to wash KD’s blood off her hands; which shows that she was feeling some type of stress or remorse for killing him.
The most significant reference to blood is when Macbeth says washing his hands with water will not clean them, rather it will turn the water red. Blood symbolizes guilt and that is why they want to wash it away so quickly.