When a Komodo dragon bites a human or it's prey the Komodo dragon secretes proteins in their mouths which is then injected into the humans or other preys skin.
This protein venom is poisonous to humans and many other animals and it will slowly kill whomever the Komodo dragon has bitten.
So if you get bitten by a Komodo dragon you need to seek medical attention right away because you could die within a few hours to a day of getting bitten.
The bite of a Komodo dragon is also very bad and painful so you'll also be in pain when the Komodo dragon bites down on you.
This is one reason why it's not good to have a Komodo Dragon as a pet as they are a large Lizard and can be very deadly if they bite you.