That popular Christmas plant, the poinsettia (Euphorbia pulcherrima), is the canary in the coal mine of the houseplant world when it comes to the toxic gas called carbon monoxide (CO).
It reacts reacting negatively to its presence even when humans show no symptoms. If your plant starts losing its leaves and bracts as soon as you bring it home and there seems to br no other reason for this reaction (for other things that can cause poinsettias leaf loss, read Why is My Poinsettia Losing Its Leaves), the level of carbon monoxide in your home may be dangerously high.
If this happens, use a commercially available carbon monoxide detector to check the level of carbon monoxide in your home. If it goes off, leave the house without delay and call 9-1-1!