Yes, URTICARIAS is a Scrabble word!

Letter values in Scrabble US: U 1, R 1, T 1, I 1, C 3, A 1, R 1, I 1, A 1, S 1.

Is it a valid word?

URTICARIAS is a valid word in the official Scrabble dictionary (US), the UK Scrabble Dictionary and Words with Friends (ENABLE).

an itchy skin eruption characterized by weals with pale interiors and well-defined red margins; usually the result of an allergic response to insect bites or food or drugs

Also: nettle rash.