Granuloma annulare is an inflammatory reaction inside the skin, not an infection. It forms a smooth ring of firm bumps that usually does not itch, does not flake, and cannot spread to anyone. Ringworm is a fungal infection. It itches, it spreads, and the edge of the ring is scaly. Run a fingertip around the border: rough and flaky points to ringworm, smooth and firm points to granuloma annulare.
Immune cells gather in a small patch of the deeper skin and push up a ring of bumps. Nothing is growing there. No germ is involved.
A dermatophyte fungus feeds on keratin in the top layer of skin. It spreads outward from where it landed, which is what makes the ring.
Small pink, purple, brown or skin-coloured bumps in a circle. The centre looks normal or slightly sunken. The surface is smooth, and it may look slightly shiny.
Red or brown ring with a flaky, bumpy, advancing border. The centre clears and often looks paler than the rim.
Most people notice it by sight, not by feel. Some rings are mildly itchy, but it is rarely the main complaint.
Itching is common and often the reason people look at the spot in the first place.
Also fingers, elbows, ankles and knees. It tends to avoid the face and the trunk.
Trunk, arms, legs, neck and face. Often near the groin, the feet, or a spot that touched a pet or a gym mat.
You cannot pass it to anyone, and you did not catch it from anyone. Sharing towels and bedding is fine.
It passes by skin contact, and through towels, clothes, bedding, mats and pets. Cats and dogs are a common source. Treated skin stops being contagious within about two days.
A ring can widen over months. Some people get several rings over time. It does not race outward.
The ring widens week by week, and scratching moves it to new areas. Untreated, one patch usually becomes several.
About half of people with a single area are clear within two years, with no mark left behind. New rings can appear years later.
It does not clear on its own. Antifungal cream clears most cases in about two to four weeks.
Many people are told to leave it alone. A strong steroid cream, or a steroid injected into the ring, can speed it up when a spot is bothersome or in an obvious place.
Clotrimazole, terbinafine or miconazole from the drugstore, applied for the full course. Keep going for about two weeks after the skin looks normal, or it comes back.
Watchful waiting costs nothing. Steroid cream is a cheap prescription.
Drugstore antifungal creams are inexpensive and do not need a prescription.
Ringworm has scale on the advancing border: The rim feels dry and slightly rough, and small flakes lift when you rub it. That scale is the fungus itself, growing in the outer layer of skin.
Granuloma annulare has no scale: The bumps sit deeper down, under an intact surface. The ring feels firm and smooth, like a raised cord under normal skin.
Add the itch to the scale and you have your answer most of the time: A smooth, quiet ring on the back of a hand is far more likely to be granuloma annulare. A rough, itchy ring that has grown since last week is far more likely to be ringworm.
Steroid cream on ringworm makes the rash look better and get worse: The steroid calms the redness and the itch, so the ring flattens and loses its scale. The fungus keeps growing underneath. Dermatologists call the result tinea incognito, because the rash no longer looks like ringworm.
Antifungal cream on granuloma annulare simply does nothing: There is no fungus to kill. Weeks of cream with no change is a common reason people finally get the right diagnosis.
This is why the order matters: If you are unsure, an antifungal cream is the safer thing to try first. It cannot make granuloma annulare worse.
A skin scraping settles the ringworm question in minutes: A few flakes are taken from the edge of the ring and looked at under a microscope. Fungal threads are either there or they are not.
A small biopsy settles the granuloma annulare question: A tiny piece of skin is removed and examined. It shows the pattern of immune cells that defines the condition. This is only done when the diagnosis is unclear.
The ring is itchy and scaly and drugstore antifungal cream has not helped in three weeks
It is on the scalp or in a beard area, which needs tablets rather than cream
The rings keep appearing in new places
The patch is painful, weeping, or crusted
You have diabetes or a weakened immune system
The rash covers a large area of the body