Are poinsettia leaves poisonous to the touch?

No, the leaves of poinsettias (Euphorbiapulcherrima) are not poisonous to the touch.

Specifically, the plant contains a milky substance that can be irritating to some people. The severest reaction will be an upset stomach or diarrhea. The notion of poinsettia body parts as being poisonous comes from its membership in the Spurge family (Euphorbiaceae) of plants. Some family members are poisonous, some not.