When are shingles not infectious?

Shingles are not infectious before the fluid-filled blisters appear or after the blisters crust over. The shingles virus is only contagious when an infected person is in the active blister phase, according to the Centers for Disease Control and Prevention.

A person with shingles should take precautions to prevent the spread of the virus, advises the CDC. The shingles rash should be kept covered at all times. Washing the hands frequently and avoiding contact with the rash is also advised. An infected person should stay away from pregnant women, premature babies and people with weakened immune systems until their blisters develop crusts.