Nikolsky's sign is a skin finding in which the top layers of the skin slip away from the lower layers when slightly rubbed.

Your doctor or nurse can use a pencil eraser to test for Nikolsky's sign. The result may be positive or negative.

A pencil eraser is placed on your skin and  gently twisted back and forth.

If the test result is positive, a blister will form in the area, usually within minutes.

A positive result is usually a sign of a blistering skin condition. People with a positive sign have loose skin that slips free from the underlying layers when rubbed. The area beneath is pink and moist and usually very tender.

• Autoimmune condition (Pemphigus vulgaris)
• Bacterial infection ( Scalded skin syndrome)
• Toxic drug reaction (Toxic epidermal necrolysis)

Call your health care provider if you or your child develop painful loosening, redness, and blistering of the skin without an obvious cause.

The conditions associated with Nikolsky's sign are serious, and most people are sent to the hospital. You will be asked for your medical history and given a physical examination. You may be given fluid and antibiotics through a vein (intravenously).

Your doctor may ask the following questions:

• When did you first notice that the skin was red or blistered?
• What other symptoms occur at the same time?

Pasternack MS, Swartz MN. Cellulitis, necrotizing fasciitis, and subcutaneous tissue infections. In: Mandell GL, Bennett JE, Dolin R, eds. Principles and Practice of Infectious Diseases. 7th ed. Philadelphia, Pa: Elsevier Churchill Livingstone; 2009:chap 90.

Schumann-Gable N. Dermatology. In: Custer JW, Rau RE, eds. The Harriet Lane Handbook. 18th ed. Philadelphia, Pa: Elsevier Mosby; 2009:chap 8.