Collocations for irritated - adj.

be, feel, look, sound
become, get

extremely, fairly, very, etc.
deeply, seriously (esp. AmE)
thoroughly
increasingly
a little, slightly, etc.
mildly
visibly

at
She was deeply irritated at being thwarted.

by
He was slightly irritated by her forgetfulness.

Irritated is used with these nouns:
sigh