Which fungus causes ringworm?

Dermatophytes remain mainly in keratin-containing tissues and can produce an expanding, scaly edge. Ringworm is also called tinea, with names that reflect location, such as body, scalp or foot infection. A [Skin Rash](/symptoms/skin-rash/) or [Scaly Skin](/symptoms/skin-scaling/) is not enough to identify the fungus because eczema and other infections can look similar.

The species may come from people, animals or soil. Moisture, skin friction and shared personal items can help transmission. A clinician may examine the skin and, when needed, test scale or hair to clarify the diagnosis.

Keep affected skin clean and dry, avoid sharing towels or clothing, and wash hands after applying treatment. For limited skin infection, a clinician or pharmacist may recommend [Topical Antifungal Treatment](/treatments/medical-dermatology/topical-antifungal-therapy/). Scalp, nail, extensive or persistent infection may need [Oral Antifungal Treatment](/treatments/medical-dermatology/oral-antifungal-therapy/), chosen for the site and person.

Arrange assessment when a rash continues to expand, returns after treatment, affects hair or nails, or fails to improve as expected. Seek prompt care for painful swelling, pus, fever, facial or eye involvement, or rapid spread. Early review is sensible for children and people with reduced immunity.

Does the appearance fit a dermatophyte infection? Is testing needed to identify the cause? Which treatment reaches this body site, and how can I prevent passing it to others?