nettlesome

Causing irritation, annoyance, or discomfort; bothersome, irksome.

My old car is very nettlesome.

Mackenzie made himself a nettlesome burr under Crook's saddle, irritating the commanding general.

Thorny; difficult to deal with, especially due to being complex or tricky.

The task of proving Fermat’s “last” theorem remains nettlesome.

Be careful what you say to him; he's a nettlesome fellow.