The classic ringworm is a red, scaly, itchy ring with a raised, expanding edge and a clearing center. On the scalp it causes scaly bald patches; in the groin, a half-moon rash; on the feet, peeling between the toes.
It is a fungus, not a worm, and it spreads by skin contact, shared items, and pets. The lookalikes to not confuse it with: eczema (no central clearing), psoriasis (silvery, symmetrical plaques), pityriasis rosea (herald patch then a trunk-wide rash), and granuloma annulare (rings without scale or itch). A clinician can confirm with a skin scraping in minutes. The treatment split follows the location: body ringworm clears with OTC terbinafine or clotrimazole cream used the full 2 to 4 weeks, while scalp and nail ringworm need prescription oral medication, so scalp involvement or spread despite proper cream use is the see-a-doctor line. And while treating: cover it, share nothing, wash hands after touching it, because it stays contagious until treatment takes hold.
What to do
Common questions
What does ringworm look like?
The textbook ringworm lesion is a ring: a red, scaly, itchy patch whose raised, active border expands outward while the center clears back toward normal skin, giving the bullseye or annular shape that names it. Size ranges from a dime to several inches, and multiple rings can overlap. It is a fungus (the CDC confirms, no worm involved), and it is contagious by skin contact, shared items, and pets. How the look shifts by location: on the body (tinea corporis), the classic ring as described; on the scalp (tinea capitis, mostly kids), scaly patches with broken hairs and hair loss, sometimes a boggy, inflamed lump (kerion) that can scar if untreated; in the groin (jock itch), a red-brown, itchy half-moon on the inner thighs, usually sparing the scrotum; on the feet (athlete's foot), peeling, itching, and cracking between the toes rather than rings; on the nails, thick, discolored, crumbling nails. The common lookalikes it gets confused with: eczema (more uniform, no central clearing), psoriasis (silvery, thick, symmetrical plaques), pityriasis rosea (a herald patch followed by a Christmas-tree rash on the trunk), and granuloma annulare (rings, but not scaly or itchy). The practical confirmation: a clinician can scrape the edge and see fungus under a microscope in minutes, and the treatment split follows the look: skin ringworm clears with over-the-counter antifungal cream (terbinafine or clotrimazole) used for the full 2 to 4 weeks, while scalp and nail ringworm always need prescription oral medication, so do not cream the scalp for a month before calling. Spreading despite proper cream use, or any scalp involvement, is the see-a-doctor line.