Kill them with arrows and/or spells before they can touch you.
Later you'll meet monsters who can inflict nasty statuses from afar.

I thought they can affect you afar--screamers at least.

Screamers are those floating heads, right? For some reason I thought of the mushroom monsters.
For those floating head screamers initiative is important. They don't have much HP so usually you can kill them before they can act if you get the initiative.