Ringworm and Jock Itch: Ring-Shaped Rashes, Causes and When to Be Seen

What it involves

MedlinePlus explains that ringworm, also called tinea, is a skin infection caused by fungi and has nothing to do with a worm. Ringworm of the body shows up as a ring-shaped rash, and jock itch is the same kind of infection in the groin.

Who this is for

• Patients with a ring-shaped, scaly, itchy patch on an arm, leg, or the trunk
• Patients with an itchy rash in the groin folds that returns after treatment
• Parents or pet owners wondering whether a rash could have come from a cat or dog
• Patients who already use an over-the-counter cream and are not seeing improvement

What to expect

• Questions about how long the rash has been there, what it looks like at the edge, and whether it itches
• A close look at the skin, since MedlinePlus says a provider can often diagnose ringworm just by looking
• A conversation about sweating, tight clothing, sports, pets, and any foot or nail problems
• A plan that may include an antifungal cream or other medicine, plus advice on keeping it from coming back

Why the fungus takes hold

MedlinePlus says the fungi behind ringworm live on the dead tissue of the hair, nails, and outer skin layers and thrive in warm, moist areas. Wet skin for a long time, small skin or nail injuries, and close contact in sports such as wrestling raise the chance of catching it. Jock itch is triggered by friction from clothing and prolonged moisture in the groin, and a foot infection can spread to the groin on the waistband of pants. The athlete's foot guide covers the foot version of the same family of infections.

What each rash looks like

MedlinePlus describes two different pictures:

• Ringworm of the body starts as small red, raised spots that slowly turn ring-shaped, with a raised, sometimes scaly border and a clearer center
• Jock itch causes red, raised, scaly patches in the creases of the upper thigh that may blister or ooze, with sharply defined edges
• Either rash can itch, and the skin may end up darker or lighter afterward

How it spreads

MedlinePlus says ringworm can spread quickly through direct skin contact, and through clothing, combs, pool surfaces, and shower floors that carry the fungus. Pets can pass it along, and cats are common carriers. Washing clothing, towels, and bedding in hot, soapy water, showering after contact sports, and treating an infected pet are all listed as ways to stop the spread.

Treatment and how long it takes

For ringworm of the body, MedlinePlus lists antifungal creams with ingredients such as miconazole, clotrimazole, ketoconazole, or terbinafine, applied twice a day for 7 to 10 days or as directed, and says not to cover the rash with a bandage. It reports that ringworm often clears within 4 weeks. For jock itch, it describes self-care that usually works within a couple of weeks, including keeping the area clean and dry and wearing loose underwear. Stronger or oral medicines come from a provider.

When home care is not enough

MedlinePlus advises contacting a provider if ringworm does not improve with self-care, and if jock itch lasts longer than 2 weeks, is severe, or keeps returning. Scratching can add a bacterial skin infection, which a provider may treat with antibiotics. Spreading redness, warmth, or pus is a sign of that, and the cellulitis guide explains what to look for.

When it is something else

Several skin problems look like ringworm. MedlinePlus lists a skin scraping examined under a microscope, a fungal culture, and sometimes a biopsy as ways a provider confirms the diagnosis when the look alone is unclear. Scaly patches that keep returning in the same places may be eczema or psoriasis instead, which the eczema guide and the psoriasis guide describe.

Sources

• MedlinePlus — Ringworm of the body
• MedlinePlus — Jock itch