How do Streets of Arkham Elixirs and Flasks work, and do they cost an action?

Question

Accepted Answer

Elixirs can be used at the start of your turn without spending an action; only component actions marked 'Action' cost one. A Flask's Willpower effect improves the skill by one under the expansion's Improvement rules. Elixirs can show up in older scenarios if the expansion is enabled in the app.

Mansions of Madness: Second Edition

How do Streets of Arkham Elixirs and Flasks work, and do they cost an action?