| Subject | Contents |
| Definition | Wood's lamp is a test that is performed in a dark room where ultraviolet light is shined on the area of interest. |
| Alternative Names | Black light test; Ultraviolet light test |
| How the test is performed | You will be seated and the lights will be turned off. After your eyes adjust to the darkness, your physician will turn on the Wood's lamp and hold it 4 to 5 inches from the area being studied. Your physician will then look at your skin for any color changes. (Take care not to look directly into the light.) |
| How to prepare for the test | No special preparation is needed. If you are treating the area in question with any topical medications, you may wish to skip an application before visiting the doctor. |
| How the test will feel | You will feel nothing during this test. Likewise, there should be no adverse side effects. |
| Why the test is performed | Your health care provider may perform this test to detect several conditions, including: Bacterial infections Fungal infections Porphyria Pigmentary alterations |
| Normal Values | Normally your skin will not fluoresce, or shine, under the ultraviolet light. |
| What abnormal results mean | Using the light, your doctor may be able to confirm a diagnosis of fungal infection or bacterial infection. Your doctor may also be able to gain insight into the cause of light or dark colored spots on your skin. |
| What the risks are | There are no risks, but avoid looking directly into the ultraviolet light, as you avoid looking into the sun. |
| Special considerations | Washing before the test may cause a false negative result. A room that is not dark enough may also alter results. Other materials may also glow. For example, some deodorants , make-ups, soaps, and even lint may be visible with the Wood's lamp. Not all infections can be detected with the light; some species of fungi and bacteria do not contain fluorescent chemicals. |
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