What should you know about Wood's lamp and human ringworm?

The examination uses ultraviolet light over a suspected patch, usually after the area has been inspected in ordinary light. Some fungal species produce a characteristic fluorescence, while others do not. A human ringworm infection may therefore look ordinary under the lamp. The clinician assesses the border, scale, itch, location, spread, and possible exposure to infected people, animals, or shared items.

A sample from the affected surface can be more useful when the diagnosis is uncertain or treatment has not worked. Skin tone, cosmetics, topical medicines, and room conditions can also change the view. The lamp supports clinical reasoning; it is not a home diagnostic tool.

Avoid sharing towels, hats, brushes, clothing, or sports equipment until the rash has been assessed. Keep the area dry and follow the clinician's instructions about stopping products before the appointment. If ringworm is confirmed, [Topical Antifungal Treatment](/treatments/medical-dermatology/topical-antifungal-therapy/) may suit skin lesions, while [Oral Antifungal Treatment](/treatments/medical-dermatology/oral-antifungal-therapy/) may be considered for sites or patterns that need medicine throughout the body. Do not scratch or cover the area with an unprescribed steroid.

Arrange review if the rash is spreading, returning, or affecting hair, nails, or the scalp. Seek prompt help for facial or eye swelling, pus, fever, severe pain, or rapidly worsening inflammation. People with reduced immunity and young children should receive tailored advice rather than relying on a lamp result.

Ask whether the findings fit [Ringworm](/conditions/ringworm/), whether a scraping is needed, how to prevent transmission, and what improvement should look like during treatment.