Ringworm (tinea corporis): recognize and treat the fungus

What it is

Dermatophyte fungi feed on keratin in the outer skin, hair and nails. “Tinea corporis” refers to infection on the body; athlete's foot and jock itch are related infections at other sites. The circular shape can be classic, incomplete or absent, especially after steroid use.

Steroid cream can temporarily reduce redness while allowing fungus to spread, producing “tinea incognito.” When ringworm is possible, avoid using a steroid alone unless a clinician has excluded fungal infection.

What it looks and feels like

• An itchy scaly patch that gradually enlarges outward.
• A raised or more inflamed edge, sometimes with small bumps or blisters.
• Partial central clearing that creates a ring, although not every case is circular.
• One lesion or multiple overlapping rings.
• Scalp infection may cause scale, broken hairs or patches of hair loss.

Causes, triggers and risk factors

• Skin contact with an infected person during sports, sex or household contact.
• Contact with infected cats, dogs or other animals.
• Shared towels, clothing, bedding, mats, combs or sports equipment.
• Warm humid environments, sweating, tight clothing and damp skin.
• Immune suppression or repeated exposure can increase severity.

Treatment and self-care

For small body lesions, a pharmacist may recommend an antifungal such as terbinafine, clotrimazole or miconazole. Follow the specific label for application frequency and duration, extend slightly beyond the visible edge and complete the course even if the rash improves early.

Keep the area clean and dry, wash hands after touching it, change clothing and towels daily, and do not share personal items. Wash bedding and sports clothing. Pets with hair loss or scaling should be evaluated by a veterinarian. Scalp and nail ringworm generally require prescription oral treatment.

Conditions that can look similar

• Nummular eczema: coin-shaped itchy patches without a consistently advancing fungal edge.
• Pityriasis rosea: one herald patch followed by many trunk lesions.
• Granuloma annulare: smooth ring of bumps with little or no scale.
• Psoriasis: thicker scale and often symmetric or recurrent sites.
• Lyme erythema migrans: expanding rash after tick exposure, often not scaly; requires medical care.

How long is ringworm contagious?

Transmission risk falls after effective treatment begins, but it does not disappear instantly. Follow school, sports or workplace guidance and keep lesions covered when practical. Continue the full treatment and hygiene measures to reduce recurrence.

Antifungal-resistant ringworm is an emerging concern. Do not repeatedly self-treat a spreading infection for months; clinical testing can confirm fungus and guide treatment.

When to see a healthcare professional

• The scalp, beard, nails, face or a large body area is involved.
• The rash is painful, draining, infected-looking or accompanied by fever.
• You are immunocompromised, pregnant or treating a very young child.
• Correct antifungal treatment has not produced clear improvement within the expected label period.
• The rash worsened after steroid cream or follows sexual contact.

Sources and further reading

We use established public-health and dermatology references and link them directly so you can verify the guidance and read further.

• Ringworm — CDC
• Ringworm prevention — CDC

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