What should you know about Wood's lamp in dermatology?

The room is darkened and the clinician holds the lamp above clean, dry skin without touching it. Some areas may look brighter, darker, or fluorescent because of pigment changes, surface organisms, or products on the skin. The observation can help define the edge of a patch and compare nearby skin, but it is not a general health scan and does not identify every skin disorder.

Results depend on the skin tone, the condition being considered, the body site, and whether creams, deodorant, makeup, fibres, or soap residue remain on the surface. A clinician interprets the colour in context and may combine the examination with a dermatoscope, scraping, culture, or biopsy when the diagnosis remains unclear.

Follow the clinic's instructions about washing the area and avoiding products before the visit. Do not apply a new cream solely because a patch looks different under the light. Keep a note of when the change began, whether it itches or scales, and any treatments already used. The examination is generally quick and does not involve contact with the skin. Ask what the observed colour means for your particular symptoms and whether another test is needed.

Arrange medical review for a new or changing patch, persistent itching, unexplained pigment loss, bleeding, crusting, pain, or a sore that does not heal. Seek prompt attention for rapidly spreading redness, swelling with fever, or eye involvement. An unusual Wood's lamp appearance should lead to appropriate assessment, not self-diagnosis.

Ask what the lamp showed, which diagnoses are being considered, whether products could have affected the view, and whether you need a scraping, culture, or follow-up examination.