Is ringworm dangerous for cats?

In healthy adult cats, ringworm is rarely dangerous — it is superficial and self-limiting, though without treatment it spreads and persists for months. In kittens, immunocompromised cats, or cats with concurrent skin conditions, it can become extensive and cause significant discomfort. The primary concern is zoonotic spread to humans — see our note on transmission below. If you notice circular hairless patches on your cat, consult your vet rather than waiting. See our when to call the vet guide for urgency context.

How is ringworm treated in cats?

Treatment typically involves antifungal medication (oral griseofulvin, itraconazole, or terbinafine), antifungal shampoo or lime sulphur dips, and environmental decontamination. Treatment duration is usually 6–12 weeks — stopping early when lesions appear resolved is a common cause of relapse, as the fungus can still be present. The Merck Veterinary Manual dermatophytosis entry covers the full treatment protocol.

Can I catch ringworm from my cat?

Yes — ringworm is one of the most common zoonotic infections transmitted from cats to humans. Microsporum canis from cats can cause circular, itchy lesions on human skin, scalp, or nails. Immunocompromised individuals and young children are most vulnerable. During treatment, wash hands after handling the cat, avoid letting the cat sleep on beds, and vacuum regularly to reduce environmental spore load. Human ringworm is treated with antifungal cream available from a pharmacist.

How do I clean my home to prevent ringworm spread?

Ringworm spores are remarkably persistent — they can survive in the environment for up to 18 months. Thorough cleaning is essential during treatment: vacuum all soft furnishings and discard the bag immediately, wash bedding at 60°C, and wipe hard surfaces with a dilute bleach solution (1:10). Restrict the cat to rooms that are easier to clean until treatment is complete. Your vet can advise on environmental antifungal sprays licensed for household use.

Ringworm — Cat Glossary

What it is

Ringworm (dermatophytosis) is a superficial infection of the skin, hair, and occasionally nails caused by fungi called dermatophytes. In cats, Microsporum canis accounts for the vast majority of cases. These fungi digest keratin — the structural protein of hair and the outer skin layer — causing localised hair loss and skin changes.

The "ring" in the name refers to the circular shape of lesions on human skin; in cats, the appearance is variable and does not always present as a perfect ring.

How cats become infected

Ringworm spreads through direct contact with an infected animal, contaminated bedding, grooming equipment, or environmental surfaces. Spores shed from infected animals can remain viable on surfaces for up to 18 months — making environmental decontamination a critical part of any treatment programme.

Kittens, long-haired cats, and cats from multi-cat environments (rescue centres, catteries) are at higher risk. Some cats — particularly Persians — appear genetically predisposed to more severe or recurrent infection.

Signs in cats

Circular areas of hair loss

The classic presentation: roughly circular patches of patchy to complete hair loss, most commonly on the head, ears, and forelimbs. The skin within the lesion may appear scaly or crusty.

Broken hair shafts

Hair in affected areas is brittle and breaks at the follicle rather than shedding cleanly. Under a Wood's lamp (UV light), M. canis-infected hairs fluoresce apple-green — though only around 50% of strains fluoresce, so a negative result does not rule out ringworm.

Skin scaling and crusting

The affected skin may develop a dry, flaky appearance. In more severe cases, crusty plaques form. Pruritus (itchiness) is variable — some cats scratch affected areas; others show no apparent discomfort.

Carrier cats (no signs)

Some cats — particularly longhairs — carry dermatophytes without showing clinical signs. These asymptomatic carriers are a significant source of environmental contamination and transmission to other animals and people.

Diagnosis

Definitive diagnosis requires laboratory testing. A Wood's lamp examination is a useful screening tool but has limited sensitivity. Fungal culture (dermatophyte test medium, DTM) is the gold standard — results take 2–3 weeks. PCR testing is faster and increasingly available through veterinary diagnostic labs. Your vet will advise on the appropriate test based on clinical presentation.

Treatment

Treatment has three components that must all be addressed simultaneously:

Systemic antifungal: oral itraconazole or terbinafine — continued for a minimum of 4 weeks beyond apparent clinical resolution, confirmed by a negative culture
Topical treatment: antifungal shampoo (miconazole/chlorhexidine) or lime sulphur dips — reduces environmental spore shedding during treatment
Environmental decontamination: vacuuming (disposing of the bag), hot washing of soft furnishings, and dilute bleach or antifungal spray on hard surfaces

In multi-cat households, all cats should be tested and treated where indicated. Isolating the affected cat during treatment reduces cross-contamination.

Zoonotic risk

Ringworm is among the most common zoonotic infections in the UK. Infected cats can transmit M. canis to humans, causing itchy, ring-shaped lesions on skin or scalp. Children and immunocompromised adults are most susceptible. If family members develop unexplained skin lesions while your cat is being treated, they should see a GP or pharmacist. Human ringworm is typically treated with topical antifungal cream (clotrimazole, terbinafine).

What it is

How cats become infected

Signs in cats

Diagnosis

Treatment

Frequently asked questions