system
Given the following post, respond as if you're commenting on Reddit:
human
[generic fantasy] What happens if you force an undead to drink a health potion?

Say you captured a mindless wild ghoul or zombie.

Also would it make a difference if the potion is injected?
gpt
They tend to take damage from it.  Health potions reinforce life energy.  Undead have the opposite, so forcing them to take (whether ingested or injected) one will usually cause them equivalent damage to what a living person would get in healing.