Ringworm of the Skin

Topic Overview

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This topic is about ringworm of the skin, groin, or hands. For information about other fungal infections, see the topics:

What is ringworm of the skin?

Ringworm of the skin is an infection caused by a fungus.

Jock itch is a form of ringworm that causes an itchy rash on the skin of your groin area. It is much more common in men than in women. Jock itch may be caused by the spread of athlete's foot fungus to the groin.

What causes ringworm?

Ringworm is not caused by a worm. It is caused by a fungus. The kinds of fungi (plural of fungus) that cause ringworm live and spread on the top layer of the skin and on the hair. They grow best in warm, moist areas, such as locker rooms and swimming pools, and in skin folds.

Ringworm is contagious. It spreads when you have skin-to-skin contact with a person or animal that has it. It can also spread when you share things like towels, clothing, or sports gear.

You can also get ringworm by touching an infected dog or cat, although this form of ringworm is not common.

What are the symptoms?

Ringworm of the skin usually causes a very itchy rash. It often makes a pattern in the shape of a ring, but not always. Sometimes it is just a red, itchy rash.

Jock itch is a rash in the skin folds of the groin. It may also spread to the inner thighs or buttocks.

Ringworm of the hand looks like athlete's foot. The skin on the palm of the hand gets thick, dry, and scaly. And skin between the fingers may be moist and have open sores.

How is ringworm of the skin diagnosed?

If you have a ring-shaped rash, you very likely have ringworm. Your doctor will be able to tell for sure. He or she will probably look at a scraping from the rash under a microscope to check for the ringworm fungus.

How is it treated?

Most ringworm of the skin can be treated at home with creams you can buy without a prescription. Your rash may clear up soon after you start treatment, but it's important to keep using the cream for as long as the label or your doctor says. This will help keep the infection from coming back. If the cream doesn't work, your doctor can prescribe pills that will kill the fungus.

If ringworm is not treated, your skin could blister, and the cracks could become infected with bacteria. If this happens, you will need antibiotics.

If your child is being treated for ringworm, you don't have to keep him or her out of school or daycare.

Can you prevent ringworm?

To prevent ringworm:

Don't share clothing, sports gear, towels, or sheets. If you think you have been exposed to ringworm, wash your clothes in hot water with special anti-fungus soap.
Wear slippers or sandals in locker rooms and public bathing areas.
Shower and shampoo well after any sport that includes skin-to-skin contact.
Wear loose-fitting cotton clothing. Change your socks and underwear at least once a day.
Keep your skin clean and dry. Always dry yourself completely after showers or baths, drying your feet last.
If you have athlete's foot, put your socks on before your underwear so that fungi do not spread from your feet to your groin.
Take your pet to the vet if it has patches of missing hair, which could be a sign of a fungal infection.

If you or someone in your family has symptoms, it is important to treat ringworm right away to keep other family members from getting it.

Cause

Ringworm infection is caused by a fungus. Fungi (plural of fungus) that cause ringworm live and spread on the outer layer of skin. Ringworm is not caused by a worm or other parasite.

Fungi are present everywhere in our environment, including on the human body. They thrive in warm, moist areas, such as locker rooms and swimming pools, and in skin folds. You can get ringworm of the skin by sharing contaminated towels, clothing, and sports equipment, and by direct contact with an infected person.

Ringworm of the skin (tinea corporis) is most commonly caused by the fungus Trichophyton rubrum, which spreads from one person to another. It can also be caused by Microsporum canis, which is spread by cats and dogs. This type is less common but causes a more severe infection.

People often get ringworm of the groin ("jock itch") by accidentally spreading athlete's foot fungus to their own groin area. People who have athlete's foot also commonly spread it to their hands (tinea manuum).

Some people are more likely to get fungal infections than others. The tendency to get fungal skin infections or to have them return after treatment seems to run in families.

Symptoms

Most ringworm infections cause a rash that may be peeling, cracking, scaling, itching, and red. Sometimes the rash forms blisters, especially on the feet.

Symptoms of ringworm of the body include a rash:

On the chest, stomach, arms, legs, or back.
With edges that are red and scaly or moist and crusted. The rash also may have small bumps that look like blisters. The centre of the rash may be clear, giving it a ring-shaped appearance, or there may be a cluster of red bumps.
That may form large, round patches.

Symptoms of ringworm of the face include a rash:

On the face, the ears, or both.
With a border that may not be very distinct.
That may get worse after being in the sun.

Symptoms of ringworm of the groin (jock itch) include a rash:

On the groin, skin folds, inner thighs, or buttocks. The rash usually does not occur on the scrotum or penis.
With edges that are very distinct and may be scaly or have bumps that look like blisters.
That may have a red-brown centre.

Jock itch and athlete's foot frequently occur at the same time.

Symptoms of ringworm on the hand include a rash:

On the palm that may be mistaken for eczema.
On the palm that is thickened, dry, and scaly, similar to athlete's foot, while skin between the fingers may be moist and have open sores.
On the back of the hand that is red and scaly, with edges that have bumps that look like blisters.

Fingernails can also be infected. For more information, see the topic Fungal Nail Infections.

Ringworm of the skin may be confused with other conditions with similar symptoms, such as eczema or psoriasis.

What Happens

Ringworm of the skin can start as a small patch of itchy, red, or scaling skin. The rash can spread and cover a large area.

Clothing that rubs the skin can irritate the rash. Sweat, heat, or moisture in the air (humidity) can make the itching and infection worse.

As the infection becomes worse, the ring-shaped pattern and red-brown colour may become more visible. If not treated, the skin can become irritated and painful. Skin blisters and cracks can become infected with bacteria and require antibiotics.

Ringworm can also spread to other parts of the body, including the feet, nails, scalp, or beard.

After treatment, the rash will go away. But ringworm can return unless you follow steps to prevent it. The tendency to get fungal skin infections or to have them return after treatment seems to run in families.

What Increases Your Risk

Your risk of getting ringworm is higher if:

You come in contact with a person who has a fungal infection or with a carrier, a person who has the fungi but does not have symptoms.
You are susceptible to fungal infections or you have had a previous fungal infection.
You have an impaired immune system due to a disease such as diabetes or cancer.
You live in a warm, damp climate.
You wear tight-fitting clothes or you let your skin stay damp for long periods, such as by staying in a wet bathing suit or sweaty workout clothes.
You are a wrestler.

When should you call your doctor?

If you suspect you have ringworm of the skin, call your doctor if:

You have patches of skin that are itchy, red, or scaly with bumps that look like blisters, and they have not improved after 2 weeks of treatment with a non-prescription antifungal product.
Signs of bacterial infection develop. Signs may include:
- Increased pain, swelling, redness, tenderness, or heat.
- Red streaks extending from the area.
- Discharge of pus.
- Fever of 38°C (100.4°F) or higher with no other cause.
The rash appears to be spreading even after treatment.

Watchful waiting

Watchful waiting is a wait-and-see approach. If you get better on your own, you won't need treatment. If you get worse, you and your doctor will decide what to do next.

You can treat ringworm at home with medicines you can buy without a prescription. If symptoms do not improve after 2 weeks of treatment with this medicine, call your doctor.

Any persistent, severe, or recurring infection should be checked by your doctor.

Who to see

Your family doctor or general practitioner can diagnose and treat ringworm of the skin. You may be referred to a specialist, such as a dermatologist.

Examinations and Tests

Doctors often can easily recognize ringworm by its ring-shaped rash. Your doctor will probably also look at a skin sample (KOH preparation) under a microscope to confirm that fungus is present.

Tests for ringworm of the skin include:

A KOH (potassium hydroxide) preparation. This test can help your doctor find out whether a fungus is causing your rash. The doctor will take a sample of your skin by lightly scraping the infected area. The sample is placed on a slide with potassium hydroxide (KOH) solution and gently heated. If fungus cells are present, the doctor can then see them with a microscope.
A Wood's light examination. This test may be used to see if the rash is caused by a fungus. Your doctor will shine a special light on your skin where you have the rash. Certain kinds of fungi glow under this light.
A fungal culture (skin culture). This test can identify the type of fungus that is causing your infection. Usually a culture is only done if the diagnosis is difficult or the skin condition is not responding to treatment. This test may take up to 4 weeks, because it takes time for the fungus to grow.

Treatment Overview

Most cases of ringworm of the skin, including jock itch and ringworm of the hand, can be treated with creams or ointments that you put on your skin to kill fungi. These are called topical antifungals. You can get many topical antifungals without a prescription. Brand names include Canesten, Micatin, Monistat, and Tinactin.

You may need to take antifungal pills (oral treatment) if the ringworm does not go away after you have tried different topical antifungals or if the infection is widespread. Oral treatments include azoles such as fluconazole (Diflucan) and allylamines such as terbinafine (Lamisil).

Your rash may start to clear up soon after you begin treatment, but it is important to use the medicine exactly as the label or your doctor says. This will help keep the infection from coming back. You will probably need to continue treatment for 2 to 4 weeks.

If not treated, ringworm can spread and the skin can become irritated and painful. Skin blisters and cracks can become infected with bacteria. If this happens, you may need to take antibiotics.

What to think about

You should treat a fungal infection right away. Severe and widespread infections can be hard to treat.

Prevention

To prevent ringworm of the skin:

Keep your skin clean and dry. Change your socks and underwear at least once a day.
Wear loose-fitting cotton clothing. Avoid tight underwear, pants, and panty hose.
Always dry yourself completely after showers or baths. After drying your skin with a towel, allow your skin to air-dry before putting your clothes on. You can also use a hair dryer, set on a cool setting, to dry your skin.
Do not share clothing, sports equipment, towels, or sheets. If you think you have been exposed to ringworm, wash your clothes in hot water with fungus-killing (fungicidal) soap.
Wear slippers or sandals in locker rooms, showers, and public bathing areas.
Shower and shampoo thoroughly after any sport that requires skin-to-skin contact.
If you have athlete's foot, put your socks on before your underwear so that fungi do not spread from your feet to your groin. Also, when towelling off after a shower or bath, dry your feet last.
Take your pet to a veterinarian if it has patches of missing hair, which may be a sign of a fungal infection. Household pets can spread fungi that cause ringworm in people.

Home Treatment

In most cases, you can treat ringworm of the skin with antifungal creams or ointments. Many are available without a prescription. Use a non-prescription antifungal cream with miconazole or clotrimazole in it. Brand names include Canesten, Micatin, and Monistat.

Wash the rash with soap and water, and dry thoroughly. For large areas of blistered sores, use compresses such as those made with Burow's solution (available without a prescription) to soothe and dry out the blisters.
Apply antifungal cream beyond the edge or border of the rash.
Follow the directions on the package. Don't stop using the medicine just because your symptoms go away. You will probably need to continue treatment for 2 to 4 weeks.
If symptoms do not improve after 2 weeks, call your doctor.

If your rash does not clear after you have tried different topical antifungals, or if the infection is widespread, you may need prescription antifungal pills.

If you have both athlete's foot and ringworm of your groin or legs, you should treat both infections. This will prevent you from re-infecting your legs or groin with the athlete's foot fungus, when you put on your underwear.

Medications

Most ringworm infections of the skin can be treated at home with non-prescription antifungal creams. The rash will usually improve within 2 weeks.

If the rash does not improve after you have used an antifungal cream and it is severe and widespread or returns frequently, you may need antifungal pills that your doctor prescribes. When you are treating ringworm, it is important to finish the full course of medicine prescribed, even if the symptoms have gone away, so that the infection does not return.

Medicine choices

The most common antifungals used to treat ringworm of the skin are:

Allylamines, such as terbinafine (Lamisil). Allylamines come as creams, pills, and spray forms.
Azoles. Oral prescription forms include fluconazole (Diflucan) and itraconazole (Sporanox). Some of these medicines are available without a prescription. Brand names include Canesten and Micatin.
Other antifungals such as tolnaftate (Tinactin). Tinactin is available without a prescription and comes in lotion, cream, gel, and spray forms.

Clotrimazole/betamethasone (Lotriderm), a combination antifungal and corticosteroid, is sometimes used to treat ringworm that is burning, itchy, and inflamed. This prescription medicine should be used with caution and for no longer than 2 weeks, because complications can occur with long-term use of corticosteroids.

What to think about

People who are taking antifungal pills should have a doctor monitor their blood counts and liver and kidney function during treatment to watch for any harmful side effects.

Credits

Current as of:
July 2, 2020

Author: Healthwise Staff
Medical Review:
Kathleen Romito MD - Family Medicine
Brian D. O'Brien MD - Internal Medicine
Adam Husney MD - Family Medicine
Martin J. Gabica MD - Family Medicine
John Pope MD - Pediatrics