Thirsty vampires. Vampires generally feed every few days, on either fresh blood from a human or another vampire, blood infused in their wine (or other drink of choice), or in the modern world, from a blood bag kept in cold storage. When a vampire becomes thirsty, veins start to spread visibly until their thirst is sated. If the vampire doesn't drink, they may suffer from hallucinations, or black outs. If they don't drink within the month, they'll go into a coma like sleep.