Is ringworm caused by a worm?

No, despite its name, ringworm is caused by fungi called dermatophytes, not by a worm. The name comes from the characteristic ring-shaped rash it produces on the skin.

How long is ringworm contagious?

Ringworm is contagious as long as the infection is active. Once appropriate antifungal treatment begins, contagiousness significantly decreases within 48 hours, but the full course of treatment should be completed to prevent recurrence.

Can pets spread ringworm to humans?

Yes, ringworm is a zoonotic infection that commonly spreads from cats, dogs, and other animals to humans. Infected animals may show patchy hair loss and scaling, or they may be asymptomatic carriers. Infected pets should be treated by a veterinarian.

InfectiousICD-10: B35One of the most common fungal infections worldwide; affects approximately 20–25% of the global population at any given time

Ringworm

Also known as: Dermatophytosis, Tinea Corporis, Tinea

Ringworm is a common fungal skin infection caused by dermatophytes — not an actual worm. It appears as a circular, red, scaly, itchy rash with a raised border and clearer center, giving the appearance of a ring. Ringworm can affect various body areas including the body (tinea corporis), scalp (tinea capitis), feet (athlete's foot), and groin (jock itch). It is highly contagious and spread through direct contact with infected people, animals, or contaminated surfaces.

Symptoms

Red, circular, scaly rash with raised edges and a clearer center

Itching, stinging, or burning

Overlapping rings of rash

Cracking, peeling, or flaking skin

On the scalp: patchy hair loss with scaling

Discolored, thick, or crumbly nails (tinea unguium/onychomycosis)

Causes

Dermatophyte fungi (Trichophyton, Microsporum, and Epidermophyton species)
Spread through direct contact with infected humans, animals (cats, dogs), or contaminated fomites
Thrives in warm, moist environments

Risk Factors

Living in warm, humid climates
Close contact sports (wrestling, martial arts)
Sharing personal items (towels, clothing, combs)
Contact with infected animals (cats, dogs, cattle)
Weakened immune system
Walking barefoot in communal showers or locker rooms

Diagnosis

Clinical examination of characteristic ring-shaped rash
KOH preparation (skin scraping with potassium hydroxide microscopy)
Fungal culture of skin scrapings
Wood's lamp examination (fluoresces for certain Microsporum species)

Treatment

Topical antifungal medications: clotrimazole, terbinafine, miconazole (for mild skin infections)
Oral antifungal medications: terbinafine or griseofulvin (for scalp ringworm or extensive disease)
Keep the affected area clean and dry
Continue treatment for 1–2 weeks after the rash has cleared to prevent recurrence

Prevention

Keep skin clean and dry, especially in skin folds
Avoid sharing personal items (towels, clothing, brushes)
Wear flip-flops in communal showers and pool areas
Wash hands after handling animals
Treat infected pets promptly

When to See a Doctor

Rash not improving after 2 weeks of OTC antifungal treatment
Ringworm on the scalp (requires oral antifungal therapy)
Widespread or multiple areas of infection
Signs of secondary bacterial infection (increasing redness, warmth, pus)

Frequently Asked Questions

Related Conditions

Eczema

Dermatological

Psoriasis

Dermatological

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