Ringworm is a fungal infection that causes ring-shaped lesions on the outer layers of the skin. These lesions are typically red and itchy, and they can appear on the scalp, outer extremities, or torso.

Ringworm is highly contagious and can spread through contact with other areas of the body and other people. Ringworm remains contagious for some time, even when a person is undergoing treatment for the infection.

Read on to find out about the treatment options for ringworm and how long the infection remains contagious after starting treatment. We also provide tips on how to prevent ringworm from spreading.

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Contact with a person that has ringworm can spread the condition.

Ringworm is highly contagious. A person may contract ringworm from an infected pet or another person.

Several different types of fungi can cause ringworm. These fungi are contagious for as long as any of their spores remain alive.

Fungal spores can live for 12 to 20 months, so it is important that a person disinfects anything that has come into contact with an infected person or animal. These objects include bedding, couch cushions, clothing, and other fabrics.

According to the Seattle Children's Hospital, ringworm stops being contagious after 48 hours of treatment.

While undergoing treatment, a person can cover the lesion to help prevent it from coming into contact with other people or objects in the environment.

A dog or cat that receives aggressive treatment for ringworm will remain contagious for about 3 weeks. If the treatment is milder or inconsistent, the ringworm is likely to remain contagious for longer. People should discuss the treatment options with their pet's veterinarian.

Ringworm spreads through direct contact with infected skin or fungal spores. The spores can live on fabrics, including clothing, couch cushions, bedding, and other porous surfaces. They also thrive in damp environments, such as public showers and locker rooms.

Ringworm is the same fungus that causes athlete's foot and jock itch. As a result, if a person has ringworm, they should avoid touching their groin area or feet. Doing so could cause the ringworm to spread to these parts of the body.

A person who contracts ringworm from a pet cannot pass it on to another human. In this case, the fungus can only pass from animal to human.

While anyone can get ringworm, certain factors can increase a person's risk of developing the infection. These include:

  • living in a hot, humid environment
  • sweating heavily
  • participating in contact sports, such as wrestling or football
  • using locker rooms or public showers
  • wearing tight shoes
  • living or working in close contact with animals
  • having a weakened immune system

In many cases, it is possible to prevent ringworm. Some steps that a person can take to prevent this infection include:

  • wearing looser fitting shoes
  • changing underwear and socks at least once each day
  • keeping the skin clean and dry
  • avoiding walking barefoot in showers and other outdoor areas
  • showering immediately after playing a contact sport and keeping all kit clean
  • washing the hands with soap and water after playing with a pet
  • seeking veterinary treatment for an infected pet

Once a person or pet has ringworm, it is important to prevent the infection from spreading.

Preventing contagion between humans

A person who has ringworm can spread the infection both to other parts of their body and to other people. To prevent this, people should take the following precautions:

  • avoid scratching or touching the ringworm lesion
  • wash the hands thoroughly after touching or treating the ringworm lesion
  • wash clothes, bedding, and towels in hot, soapy water

People who have athlete's foot should also take the following precautions:

  • avoid leaving worn socks lying around
  • use an ultraviolet shoe sanitizer or ozone cabinet to disinfect shoes
  • avoid walking barefoot in the home

People who have ringworm should avoid sharing their personal items. Some items to avoid sharing include:

  • bedding
  • towels
  • clothing and accessories
  • hairbrushes
  • makeup

Preventing contagion from pets to humans

If a pet has ringworm, a person should help prevent the infection from spreading by:

  • seeking veterinary treatment for the pet
  • having the veterinarian check other household pets for ringworm
  • cleaning, vacuuming, and disinfecting areas of the home that the pet spends time in
  • wearing gloves and long sleeves when handling the pet
  • washing the hands with soap and water after touching the pet

Treatment typically involves the direct application of an antifungal cream to the ringworm lesion. These creams are available over the counter.

When applying the cream, people should cover the visible lesion and spread the cream out to 2.5 cm beyond the lesion's borders. People should continue to use the cream for at least 7 days after the lesion has completely cleared.

According to one study, ointments or creams could take about 4 weeks to clear a ringworm infection. However, the exact duration of the infection depends on the location and severity of the lesion.

A lesion that forms on an area of the body with little to no hair may resolve in 2–4 weeks with treatment. If the infection is severe or in an area with a lot of hair, it can take longer to heal.

Ringworm that occurs on the scalp requires prescription medicine, such as oral antifungals. The doctor may also prescribe a medicated shampoo.

Without treatment, ringworm can disappear within a few months. However, the person is contagious to themselves and others during this time.

Ringworm is a highly contagious fungal skin infection. It can occur anywhere on the body but is particularly common in the groin area and on the feet.

A person can use medicated ointments and creams to treat ringworm topically. For more severe infections, a person may need to take oral antifungal medications.

Ringworm remains contagious during the first 48 hours of treatment in people and for about 3 weeks from the start of aggressive treatment in pets. In both cases, untreated ringworm remains contagious for much longer.

The fungal spores themselves can live for up to 20 months. During this time, people should take the necessary precautions to prevent reinfection.