Thioridazine & mesoridazine are the only anti-psychotics associated with single-drug fatal overdoses as these have quinidine-like actions & thus can induce ventricular arrhythmias, management of these should be as for tricyclic antidepressants. Other anti-psychotics are rarely fatal on OD.
Symptoms of overdose with other antipsychotics include:
drowsiness, agitation, coma
NM excitability which may lead to convulsions (may be Mx with diazepam or phenytoin)