What should you know about Wood's lamp for ringworm detection?

A clinician examines the suspected skin in a darkened room with ultraviolet light. Certain organisms can create a bright or coloured fluorescence, which may help draw attention to an affected area. Ringworm itself can look like an expanding, scaly patch or ring, but its appearance changes with skin tone, body site, and previous treatment. Some genuine infections remain non-fluorescent.

The lamp cannot tell whether every rash is fungal, and a visible glow can have more than one explanation. If confirmation matters, the clinician may collect surface scale, hair, or nail material for testing. The result is then combined with symptoms and examination findings to choose an appropriate plan.

Before assessment, follow instructions about washing and product use so residue does not obscure the skin. Record any creams or antifungal medicines you have applied. If ringworm is diagnosed, use [Topical Antifungal Treatment](/treatments/medical-dermatology/topical-antifungal-therapy/) as directed; scalp, nail, hair, or extensive disease may need [Oral Antifungal Treatment](/treatments/medical-dermatology/oral-antifungal-therapy/). Describe any [Skin Rash](/symptoms/skin-rash/) or [Scaly Skin](/symptoms/skin-scaling/) to the clinician rather than relying on the lamp alone.

Book an assessment for a spreading lesion, recurrent rash, scalp hair loss, nail thickening, or symptoms that do not improve with an appropriate plan. Seek prompt care for fever, marked swelling, pus, severe tenderness, or involvement near the eye. A child, pregnant person, or person with reduced immunity may need individualized treatment advice.

Ask what the lamp finding means, whether a sample should be tested, which body sites need checking, and when you should expect the rash or scale to improve.