General guidance — not a diagnosis. When in doubt, call your vet.
Ringworm in cats is not a worm — it is a fungal skin infection caused by dermatophytes, most commonly Microsporum canis. Despite the misleading name, it spreads easily to other pets and to people, making treatment a household matter, not just a cat matter. Most cats respond well to antifungal therapy within 4–8 weeks, but untreated cases can persist for months and seed the entire home environment.
Last reviewed: June 2026
What Ringworm Looks Like in Cats
Feline dermatophytosis most often presents as circular patches of hair loss (alopecia) with a scaly, crusty edge — hence the "ring" in ringworm. The lesions are typically found on the face, ears, forelimbs, and tail. Some cats, particularly long-haired breeds and kittens, carry the fungus without showing obvious skin changes (asymptomatic carriers), making silent spread within multi-cat households especially common.
Classic signs include:
- Circular, well-defined bald patches, 1–4 cm in diameter
- Broken, stubby hairs around lesion edges
- Scaling, crusting, or mild redness at the lesion border
- Itching is variable — many cats show little to no scratch response
- Facial folliculitis or chin acne in some cases
Microsporum canis fluoresces apple-green under a Wood's lamp in about 50% of infections — a useful screening test but not definitive. Confirmatory diagnosis requires fungal culture (dermatophyte test medium, or DTM) or PCR. Culture is the current diagnostic standard, though results take 10–14 days.
According to Moriello et al., 2017, JFMS, a systematic review of feline dermatophytosis management, combination therapy — topical antifungal (lime sulfur dip or miconazole/chlorhexidine shampoo) plus systemic itraconazole or terbinafine — is significantly more effective than either approach alone and shortens treatment time.
Treating Ringworm in Cats and Decontaminating Your Home
Effective management requires treating the cat AND the environment simultaneously. Fungal spores can survive in carpet, bedding, and upholstery for up to 18 months.
For the cat:
- Systemic antifungals: Itraconazole (dose determined by your veterinarian) or terbinafine are first-line options in cats. Course length is typically 6–12 weeks.
- Topical therapy: Twice-weekly lime sulfur dips or miconazole/chlorhexidine shampoo significantly reduce environmental spore shedding and accelerate cure.
- Clip long fur around lesions to improve topical penetration and reduce shedding.
For the home:
- Wash all bedding, cat trees, and soft toys in hot water.
- Vacuum carpets and hard floors daily during treatment, discarding vacuum bags.
- Disinfect hard surfaces with diluted bleach (1:10) or an accelerated hydrogen peroxide product.
- Isolate infected cats from other pets and from immunocompromised people.
Treatment costs typically run $150–400 for diagnostics and a 6–8 week antifungal course. Extensive household decontamination for multi-cat homes may add significant time and materials cost.
When to See a Vet
Call your vet today if:
- You notice circular hair-loss patches, especially on the face or forelimbs, that are spreading
- Any person in the household (especially a child, elderly person, or immunocompromised individual) develops a ring-shaped rash on their skin
- Your cat has been exposed to a newly adopted kitten or a cat from a shelter
- Lesions are not improving after 2 weeks of over-the-counter antifungal attempts
Go to the ER immediately if:
- Skin lesions are rapidly spreading and your cat appears systemically unwell (fever, not eating) — this is rare with ringworm but can indicate a secondary bacterial infection requiring urgent care
- A household member with a compromised immune system develops rapidly spreading skin lesions after cat contact
For cat owners
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Describe what you're seeing. You'll get a few follow-up questions about your cat, then where it lands — vet today, watch closely, or no visit needed — and what to do at home meanwhile.
Frequently Asked Questions
How much does treating cat ringworm cost? Diagnostics (Wood's lamp, fungal culture, or PCR) run $80–200. Systemic itraconazole for 6–12 weeks costs $50–150 depending on the cat's weight. Add topical dip supplies and the total per-cat treatment usually runs $200–450. Multi-cat households multiply those costs.
Can I catch ringworm from my cat? Yes. Microsporum canis is a zoonotic pathogen, meaning it infects humans. Children, elderly individuals, and people with weakened immune systems are at highest risk. Contact your physician if you develop a circular scaly rash after handling an infected cat.
How long is a cat with ringworm contagious? A cat remains contagious until two consecutive negative fungal cultures — typically taken 2–4 weeks apart — confirm elimination. This often means 8–12 weeks of treatment before the all-clear.
Will ringworm go away on its own in cats? In immunocompetent adult cats, spontaneous resolution can occur over 3–4 months. However, treatment is strongly recommended to shorten the contagious period, protect household members, and prevent environmental contamination. The AAFP-AAHA Feline Life Stage Guidelines, 2021 emphasize treating all culture-positive cats, including asymptomatic carriers.
Does my other cat need to be treated too? Yes. All cats sharing the same household should be cultured and treated if positive. Asymptomatic cats can shed spores and reinfect treated cats, so treating only the visibly affected animal while ignoring others is a common reason for treatment failure.
Still Not Sure if Your Cat Needs a Vet?
When you're not sure if this is wait-and-see or call-tonight, Voyage AI Vet triages in under 2 minutes. Describe what you're seeing in chat, share photos of the bald patches, scaly borders, or skin changes on your cat, or hop on a live video call if you want a second pair of eyes. Every answer comes with citations to the actual veterinary literature it's pulling from — so you see exactly where the guidance comes from, not just a chatbot's word.