How long is chicken pox contagious?

Varies: Patients (usually children) are infectious to others for roughly 2 days before the blisters occur and then until the blisters have formed scabs covering them completely, about 4 to 5 days.

Around 10 days: Generally 1-2 days prior the onset of the rash. Then until there are no new ones and all the old lesions are scabbed over.

School requirements: We acknowledge that these kids are contagious before the spots appear, for 1-2 days. This makes containing spread problematic to start. We try to exclude them from school or public places to prevent spread. The general rule is to exclude them until the last new spot has crusted and dried, or at least 7 days from the first spot.

About a week: Chickenpox tends to emerge in waves of new spots over a period of 2-5 days.The blister grows, pops & crusts usually within a single day. A person is considered contagious for 1-2 days before to 6 days after the emergence of the rash.

14 to 21 days: Chicken pox is contagious even before the rash appears and remain contagious till the last blister has scabbed