tasmin stanam durjara-viryam ulbanam
ghorankam adaya sisor dadav atha
gadham karabhyam bhagavan prapidya tat-
pranaih samam rosa-samanvito ’pibat
Translation by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada:
On that very spot, the fiercely dangerous Raksasi took Krsna on her lap and pushed her breast into His mouth. The nipple of her breast was smeared with a dangerous, immediately effective poison, but the Supreme Personality of Godhead, Krsna, becoming very angry at her, took hold of her breast, squeezed it very hard with both hands, and sucked out both the poison and her life.
Purport by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada:
Lord Krsna was not angry at Putana for His own sake. Rather, He was angry because the Raksasi had killed so many small children in Vrajabhumi. Therefore He decided that she should be punished by having to forfeit her life.