How Long Is Ringworm Contagious In Cats After Starting Treatment (And Why)?

Exact Answer: 3 Weeks

Ringworm is not a worm but fungi that infect the skin, hair and nails. Ringworm infection can occur in all domestic animals, cats or dogs, and in humans. 

It gets its name from the round, red raised ring marking the boundary of the infection. 

Ringworm is highly contagious, and transmission occurs by direct contact with the fungus. It may be passed by contact with an infected animal, touching contaminated objects or surfaces. 

Once diagnosed, a ringworm infection remains contagious for at least three weeks, depending on the intensity of the treatment. 

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How Long Is Ringworm Contagious In Cats After Starting Treatment?

The duration for which the infection is contagious depends on the type of treatment used. Generally, the more aggressive the treatment, the lesser time it remains contagious as the cat heals faster. Hence, the fungi are infectious for three weeks with aggressive treatment and an extended period with minimal measures. 

A cat is declared free of infection only after two negative fungal cultures indicating successful treatment. 

There are two types of treatments prescribed by the doctor. They are topical or oral medications. 

Topical treatment includes the use of sulfur baths, topical shampoos and lotions. One must give the affected cat a sulfur dip or sulphur bath twice a week. A sulphur bath prepared by dissolving 8 ounces of lime in one gallon of water shows its effect in 30 to 60 days until the cat tests negative. Miconazole with chlorhexidine is an effective treatment available as a rinse and shampoo. However, the rise alone takes 48 days to cure ringworm. Hence, one must use both together for faster treatment.

Cats also receive oral fungal medications to speed up treatment. These drugs include itraconazole, ketoconazole and griseofulvin. With this treatment, one will notice an improvement in 14 to 21 days. 

Environmental clean-up is also essential. Cleaning and sanitizing all surfaces the cat can touch is required to not transmit the disease to other pets and humans in the house. 

In summary,

Type Of Treatment UsedTime Taken For The Infection to Heal
Lime sulphur bath30 days
Miconazole and chlorhexidine rinse48 days
Topical and Oral medications together14 to 21 days

Why Is The Ringworm Contagious For So Long In Cats After Starting Treatment?

Generally, kittens, old cats and cats with long matted hair are susceptible to the infection and require treatment.

A lime-sulfur solution is effective as it sterilizes the fur to prevent the further growth of ringworm. Medicated topical treatments help remove infective crusts, scales, and spores from the coat. Without topical therapy, treatment would take time and would be more expensive.

Oral medication like Itrafungol binds to fungal proteins, thereby causing irreversible damage to its structure. This degradation of fungi coupled with sulphur baths and topical shampoos help cure ringworm in two to 4 weeks.

While topical and oral treatments do the trick, one can further speed up the process with a few physical changes. Firstly, chopping the cat’s hair is essential. It allows for easy and direct application of topical medicines, thus, speeding up the healing procedure. 

Environmental clean-up is essential to prevent the reinfection of indoor cats. The ringworm fungus uses keratin protein as its nutritional source. It digests the skin and hair, allowing it to penetrate the hair and continue growing. Therefore, hair shafts become weak, brittle, and easily broken. These fragments spread in the environment with thousands of pores, which further infect other pets or people. Hence, one must shave short hair kittens if more than five infected spots appear on the skin. If lesser than five is present, then only the areas surrounding the infection are shaved. One must shave long hair kittens regardless of spots present on the skin.


Treating ringworm infections can be tedious and frustrating for cat owners and veterinarians. However, to prevent the further spread of the disease, it is required. Aggressive topical and oral therapy combined with diligent environmental decontamination is the way to go. 



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Hi! I'm Nidhi.

Here at the EHL, it's all about delicious, easy recipes for casual entertaining. So come and join me at the beach, relax and enjoy the food.

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