mad, insane, out of one's mind, deranged, demented, not in one's right mind, certifiable, of unsound mind, crazed, lunatic, unbalanced, unhinged, unstable, disturbed, frenzied, raving, distraught, mad as a hatter, mad as a March hare;

Latin non compos mentis

informal crazy, mental, off one's head, out of one's head, off one's nut, nuts, nutty, nutty as a fruitcake, off one's rocker, not (quite) right in the head, raving mad, bats, batty, bonkers, cuckoo, loopy, loony, bananas, loco, dippy, screwy, touched, gaga, doolally, up the pole, not all there, out to lunch, not right upstairs, away with the fairies

British informal barmy, crackers, barking, barking mad, round the twist, off one's trolley, as daft as a brush, not the full shilling, two sandwiches short of a picnic

North American informal buggy, off the wall, nutsy, nutso, out of one's tree, meshuga, squirrelly, wacko, gonzo

Canadian & Australian/New Zealand informal bushed

New Zealand informal porangi