A Wood's lamp examination is a test that uses ultraviolet (UV) light to look at the skin closely.
Black light test; Ultraviolet light test
You will sit in a dark room for this test. The test usually takes place in a dermatologist's office. The health care provider will turn on the Wood's lamp and hold it 4 - 5 inches from the skin to look for color changes.
You do not need to take any special steps before this test. Ask your doctor if you avoid putting creams or medicines on the area of the skin being studies before the test.
You will feel nothing during this test.
Your health care provider may do this to look for skin problems including:
Normally your skin will not shine under the ultraviolet light.
A Wood's lamp exam may help your doctor confirm a fungal infection or bacterial infection. Your doctor may also be able to learn what is causing any light- or dark-colored spots on your skin.
There are no risks. Avoid looking directly into the ultraviolet light.
The following things can change the results of the test:
Not all types of bacteria and fungi show up under the light.
Harrison S, Piliang M, Bergfeld W. Hair disorders. In: Carey WD, ed. Cleveland Clinic: Current Clinical Medicine 2010. 2nd ed. Philadelphia, Pa: Saunders Elsevier; 2010.
Morelli JG. Evaluation of the patient. In: Kliegman RM, Behrman RE, Jenson HB, Stanton BF, eds. Nelson Textbook of Pediatrics. 19th ed. Philadelphia, Pa: Saunders Elsevier; 2011:chap 637.