Stainless-Steel Crown (SSC) placement is a common treatment in children, usually without significant adverse consequences. The present case series reports six healthy children were admitted to emergency rooms in two medical centers with delayed excessive bleeding from their gingiva, adjacent to newly placed SSCs. The bleeding, in some cases, was so extensive, that it induced vomiting and anxiety, among the children and their parents, and in two cases required surgical suturing. In all six cases, the most probable etiology was a toxic reaction to the released nickel or chromium ions from the SSCs, exacerbated by contact with wounded and bleeding gingiva. Expression of this cytotoxic mode of action, due to metal ions released from SSCs, is not well documented in children. Our aims are to raise awareness of this unique complication and to suggest an approach to minimize and prevent its occurrence. Recommended immediate treatment includes frequent rinsing of the gingiva to wash out released metal ions and decrease their toxic effect. Furthermore, in the following appointments, we recommend using only SSCs previously soaked in water for several weeks, using zirconia crowns, or using Hall’s technique when appropriate.