Ringworm (Tinea Corporis)
Ringworm (tinea corporis) is a superficial fungal infection of the skin, managed per the American Academy of Pediatrics Red Book and a 2024 dermatology expert panel.
Symptoms
An itchy, ring-shaped, scaly patch with a raised, red, well-defined border and often central clearing -- the classic "ring" appearance that gives the condition its name.
Causes and risk
Dermatophyte fungi, spread by direct contact with an infected person, animal, or contaminated surface (gyms, locker rooms); warm, humid conditions and close-contact sports favor spread.
How it is evaluated
Diagnosis is often clinical from the classic ring pattern; a KOH prep or culture confirms the diagnosis when it's uncertain, recurrent, or resistant to initial treatment.
Treatment
Topical antifungals (terbinafine, clotrimazole) applied 1-2 cm beyond the visible border are first-line and supported by a Cochrane review of over 18,000 participants; oral terbinafine is reserved for widespread or refractory infection. Combination antifungal-steroid products are specifically discouraged, per AAP Red Book guidance.
When to seek care
A rapidly spreading rash, signs of bacterial superinfection, or ringworm that worsens despite treatment (which can signal a resistant strain) warrants prompt evaluation.