Where does ringworm come from?

Ringworm comes from contagious fungi that spread through contact with an infected person, animal, surface, or shared item. The name is misleading: ringworm is not caused by a worm. The infection may begin when fungal particles reach irritated, damp, or broken skin and multiply in the outer skin layer. People and pets can sometimes carry and spread the fungus even when the signs are easy to miss.

Spread can happen during close skin-to-skin contact, from handling an infected pet, or by touching items such as towels, clothing, bedding, sports equipment, hairbrushes, and grooming tools. Shared floors and damp communal areas may also transfer the fungus. Scratching can move it from one body area to another.

Ringworm often causes an itchy, scaly patch that gradually expands, sometimes with a clearer centre and a more active edge. It can affect the body, scalp, feet, groin, hands, or nails, and its appearance is not always a neat ring. A rash or scaling has other possible causes, so a clinician may examine the skin and, when needed, test a small sample before confirming the diagnosis.

Keep the affected area clean and dry, wash your hands after touching it, and avoid sharing towels, clothing, bedding, or personal grooming items. Launder fabrics that have contacted the area and clean commonly handled equipment. Try not to scratch, because broken skin can become infected and the fungus can spread.

Arrange a dermatology assessment if a new scaly or expanding patch is not settling, if several household members have similar symptoms, or if a pet has a suspicious bald or scaly area. Treatment may involve a topical antifungal treatment for limited skin infection; infection involving the scalp, nails, extensive skin, or treatment-resistant areas may need an oral antifungal treatment. Use the recommended medicine for the advised duration, even if the skin starts looking better sooner.

Seek prompt medical advice when the area is rapidly spreading, very painful, warm, swollen, draining, or associated with fever. Arrange an early review for ringworm on the scalp, around the eyes, or over a large area, and for a person with reduced immunity, diabetes, or a medicine that affects immune function. Scalp infection can cause tender swelling and hair loss and needs clinician-guided treatment.

If the diagnosis is uncertain or the rash worsens after using a steroid cream, stop self-treating and ask for an examination. Steroids can temporarily reduce redness while allowing a fungal infection to extend, which can make its pattern harder to recognise.

Ask whether the appearance fits ringworm or another cause of a rash, whether a skin scraping or other test is useful, which body sites need checking, and how to prevent spread to household members or pets. Tell the clinician about recent contact with animals, shared sports equipment, similar symptoms at home, and any creams or medicines already used.