Ringworm isn’t a worm at all. It’s a fungal skin infection that gets its name from the distinctive ring-shaped rash it creates: a pink-to-red circular patch with raised, scaly borders that expands outward while the center clears, making it look like a worm curling under the skin. That classic ring pattern appears on the body, but ringworm can also affect the scalp, feet, groin, and nails, and it looks different in each location.
The Classic Ring-Shaped Rash
On the body, ringworm starts as a flat, discolored patch that may feel dry and scaly. Over the next one to three weeks, the patch grows outward. As it expands, the outer edge stays raised and scaly while the center begins to look like normal skin again. This creates the hallmark ring shape. The rings can be as small as a coin or spread to several inches across, and multiple rings can overlap.
On lighter skin, the rash typically looks pink to red. On darker skin tones, it often appears brown, purple, or gray, and the central clearing can be harder to spot because the fungal infection sometimes leaves behind darker pigmentation in the center. There’s also a less common variant that skips the ring shape entirely, instead forming round, scaly patches studded with small bumps or pus-filled spots and no clear center.
Ringworm on the Scalp
Scalp ringworm, most common in children, doesn’t always form an obvious ring. Instead, it tends to show up as swollen, red patches with dry, scaly skin and noticeable hair loss. There are two patterns worth knowing. In “black dot” ringworm, hair shafts break off right at the scalp surface, leaving behind tiny dark dots across the bald patch. In “gray patch” ringworm, hairs break slightly above the surface, leaving short stubs that give the area a dull, grayish look. Both types can be itchy and may develop painful, swollen lumps if the infection triggers a stronger immune response.
Athlete’s Foot: Three Patterns
Ringworm on the feet, commonly called athlete’s foot, rarely looks like a ring. It has three distinct presentations:
- Interdigital: The most common type. The skin between your toes (usually the fourth and fifth) turns red, peels, cracks, and becomes soggy-looking. It’s typically itchy.
- Moccasin: A chronic form that covers the sole and sides of the foot in a moccasin-like pattern. The skin becomes thick, dry, and scaly, sometimes with a pinkish tint. Both feet are usually affected. It can be so mild that people mistake it for dry skin.
- Vesicular: The most painful type. Fluid-filled blisters form on the arch or front of the sole. They itch, burst, and leave behind raw, scaly, red skin.
Jock Itch in the Groin
Ringworm in the groin area starts in the skin crease where the thigh meets the torso and spreads outward down the upper thigh and toward the buttocks. The border of the rash is often lined with small blisters, giving it a bumpy, well-defined edge. The color ranges from red to brown to purple or gray depending on skin tone. It tends to be intensely itchy, especially in warm, sweaty conditions.
Nail Fungus
When the same group of fungi infects a nail, the result looks nothing like a ring. It usually begins as a white or yellowish-brown spot under the tip of a fingernail or toenail. As the infection works deeper, the nail thickens, becomes brittle or ragged at the edges, and may pull away from the nail bed. Severely infected nails can become misshapen and develop a noticeable smell. Toenails are affected far more often than fingernails, and the infection can take months to become obvious because nails grow slowly.
How to Tell It Apart From Eczema
The rash most commonly confused with ringworm is nummular eczema, which also forms coin-shaped patches of itchy, irritated skin. The key difference is the border. Ringworm patches have a distinct raised, scaly outer edge with a clearing center. Nummular eczema patches are uniformly dry and scaly across the entire spot, sometimes oozing or crusting, without that ring-like border. If you’re unsure, a doctor can do a simple skin scraping to check for fungus under a microscope.
Spotting It on Pets
Ringworm is a zoonotic infection, meaning it passes between animals and people through direct contact. In dogs and cats, the signs include patchy hair loss, scaly or crusty skin, redness, and small bumps. Dogs sometimes develop a raised, spongy lump called a kerion at the infection site. Cats, especially Persians, can carry ringworm with very subtle signs or even no visible symptoms at all, which makes them a common source of human infections. If a new rash on your skin coincides with hair loss patches on your pet, both of you likely need treatment.