Although a 1-week supply of tricyclic antidepressants is generally considered safe, the author shows that this amount can be severely toxic. Six of 12 instances of low-dose (500-1000 mg) amitriptyline overdoses were life threatening. The author suggests that prescription guidelines for tricyclic antidepressants be tightened and that physicians prescribe less than a 1-week supply to potentially suicidal patients.