The Baneberry Potion is a potion and strongly suspected poison.
Behind the scenes
This potion is strongly believed to be a poison not only because its main ingredient is highly toxic but also because the TCG card that it debuts on is very damaging. Its also blood red, which doesn't bode well.
Interestingly, the TCG card that this potion debuts on can do damage to beasts and beings alike, implying that is poisonous to both.