Dead Man's Blood

Dead Man's Blood A poison to vampires that incapacitates them for a short period of time. When the blood from a dead human is injected into a vampire it induces a blood sickness, causing them to become very weak. – Pad of Definitions (1.20 Dead Man's Blood), Official Website

The method of incapacitating a vampire with blood from a dead person is part of vampiric folklore. Tricking a vampire into drinking blood from a dead person to kill him has also been used quite a few times in vampiric tales, notably Interview with the Vampire, wherein the vampire must stop drinking the blood of her/his victim before she/he dies, as drinking blood after death is harmful to the vampire. In Supernatural, Dead Man's Blood has been used as follows:

• Dead Man's Blood is used by John in 1.20 Dead Man's Blood to restrain Kate, when he uses her as bait to lure out Luthor and get the Colt

• Gordon uses it in 2.03 Bloodlust to torture Lenore.

• Dean injects Lucy with dead man's blood to capture her in 3.07 Fresh Blood.

• Samuel gives Dean a syringe of it when he goes to infiltrate the vampire nest in 6.05 Live Free or Twihard

• The Alpha Vampire is given an intravenous drip of dead man's blood to restrain him in 6.07 Family Matters