Torturous describes anything that involves terrible suffering. Visiting a veal farm and witnessing the torturous conditions the calves are kept in might convince you to become a vegetarian.
The adjective torturous is good for describing physically painful situations, especially if the pain is truly agonizing. You might read about the torturous experiences of Somalis in refugee camps, or the torturous pain of being trapped in a car after a bad accident. The basis of the word torturous is torture so be sure to save it for truly excruciating events. The Latin root is torquere, or to twist, turn, or distort.