Do nurses have to be certified in critical care to work in the icu?

No: Training in critical care is a must for rns who work there, but a special certification can be obtained (ccrn) which denotes advanced training and expertise. Rn's have to pass a special test to get this qualification and only a minority of critical care rn's have it.

Certification: Each state and each hospital has its' own set of requirements for nurses to work in an intensive care unit. To find out more about this you can contact your state board of nursing or the hospital in question.