Damage Health is an adverse effect that can occur to both the hero, or any target in the Elder Scrolls series. Damage Health causes a loss of health by a specified amount.
In Skyrim, the Damage Health effect is always instant. However, there is a similar effect known as Lingering Damage Health which does damage over time.
The following alchemical ingredients have the Damage Health (Skyrim) effect, along with where on the effects list it appears for each.