Adrenalin

Adrenaline was a substance produced by the adrenal gland during times of stress. (COMIC: Ripper's Curse)

It was poisonous to Blood Bugs. (COMIC: City of the Damned)

Leechers fed by draining the minerals, pheromones, and stimulants including adrenaline from their prey's kidneys and adrenal gland. (COMIC: Ripper's Curse)

The Mire fed on adrenaline and testosterone. (TV: The Girl Who Died)