Anodyne

Something that reduces pain or ailment, especially as an analogy

Examples:

It excites in him the gratifying reflection that his country has been the first to prove to the world two truths, the most salutary to human society, that man can govern himself, and that religious freedom is the most effectual anodyne against religious dissension
— Thomas Jefferson, letter to Jacob De La Motta (1820)

The heart asks pleasure first,
And then, excuse from pain;
And then, those little anodynes
That deaden suffering;
— Emily Dickinson, Poems (1891)

Novels so often provide an anodyne and not an antidote, glide one into torpid slumbers instead of rousing one with a burning brand.
— Virginia Woolf, A Room of One’s Own (1929)

Etymology:

From the Greek anodynos, an = without, dyne = pain. May come from the same word as a root that means “to eat”. Like dining on your pain.