A round, itchy patch of skin with a raised, scaly edge and a paler centre is very likely ringworm — a fungal skin infection. The single most important thing: do not buy a cream that stops the itch within a day or two. According to CDC, a cream containing a corticosteroid makes a fungal infection worse.
Recognising ringworm
The clearest sign is the edge: the fungus spreads outwards from the rim, so the rim is red, raised and scaly while the centre is paler — forming a ring, sometimes several overlapping rings.
- On light skin it looks red; on dark brown skin it can look purple, brown, grey or black — do not wait for it to be “red” before you suspect it
- Moderate, persistent itching; the patch widens over days to weeks, rather than erupting overnight
- According to CDC, signs appear roughly 4 to 14 days after the skin comes into contact with the fungus
It does not form a neat ring everywhere. Between the toes: red, puffy, peeling, itchy, often starting between the smallest toe and the one beside it. Groin: scaling in the fold, spreading to the inner thigh. Scalp: scaling with hair loss in patches. Nails: discoloured, thickened, brittle, and they may lift away from the nail bed.
What it is mistaken for
What is distinctive about ringworm is the ring-shaped edge spreading gradually outwards. Here is what the conditions it is confused with look like instead:
| Mistaken for | What is distinctive about that condition |
|---|---|
| Scabies | Intense itching that worsens at night, between the fingers and in skin folds, with fine burrows like a pencil mark; people in the household start itching one after another |
| Rove beetle dermatitis (kiến ba khoang, common in Vietnam) | A long streak following the direction a hand swept, burning rather than itching, with the burning becoming obvious hours later |
| Chickenpox | Blisters appearing in several waves all over the body, usually with a fever |
| Eczema, psoriasis | Often symmetrical on both sides, with no ring-shaped edge spreading outwards. According to CDC, ringworm is hard to tell apart from these two |
The most expensive mistake: the cream that stops the itch overnight
A great many over-the-counter tubes are combination products containing a corticosteroid. Applied to ringworm, the itch settles very quickly, so the patient believes it is the right medicine and keeps applying it. But according to CDC, a corticosteroid makes the fungus worse in two ways: it reduces the skin's local ability to fight the fungus, and it distorts the lesion so it loses its characteristic ring-shaped edge. The result is a double loss — the fungus spreads further, while the sign the doctor needs in order to recognise it has been blurred.
Checking a tube you have at home: corticosteroid ingredient names usually end in “-sone” or “-solone”. If you are not sure, ask a pharmacist rather than trying it. If you have already used it, stop and take the tube with you to the appointment.
What to do now
- Keep that area of skin clean and DRY — fungus thrives where it is damp. Dry between the toes and the groin fold last, so you do not carry the fungus elsewhere
- Photograph the lesion and note the date you first saw it, so the doctor can tell whether it is widening or shrinking
- Do not share towels, clothes, bed sheets, combs, hats or sports kit; change socks and underwear daily; do not put sweat-damp clothes back on
- Wear sandals in shared bathrooms and changing rooms — CDC names the floors of these places as a route of spread
- Look again at the pets: a cat or dog losing hair in patches with scaling is a sign of fungus. Have a vet look; wash your hands after touching them
What not to do
- Do not apply a tube containing a corticosteroid, a tube prescribed for someone else, or a tube left over from a previous episode
- Do not apply crushed leaves, alcohol, vinegar, lime or toothpaste, do not apply warming balms; do not scrub with a stone or a brush — broken skin is how bacteria get in
- Do not bandage it tightly or cover it in plastic “to help the cream soak in” — trapped moisture makes things easier for the fungus
- Do not shave and do not pull out hair around a patch of scalp ringworm
- Do not stop the medicine as soon as it improves — CDC states plainly: use it for as long as you were told
Commonly used medicines: topical clotrimazole, miconazole, terbinafine, ketoconazole; prescription oral medicines include griseofulvin, terbinafine, itraconazole and fluconazole. The names are given so you recognise what you have been prescribed — which one, cream or tablet, and for how long is for the doctor or pharmacist to decide.
Scalp ringworm in children: a cream is not enough
This is where parents often lose weeks for nothing. According to CDC, creams, lotions and powders do NOT work on ringworm of the scalp, because the fungus sits inside the hair root where a cream cannot reach. This group needs oral medicine prescribed by a doctor, with a course measured in months — stopping early because it looks better means going back to the beginning.
When you must be seen
Be seen TODAY, do not wait, if: the affected area is swollen, hot and painful, oozing pus, with red streaks spreading outwards, or there is a fever as well — that is a bacterial infection on top of the fungus; the patch has spread quickly after you applied a tube whose ingredients you do not know; or the patient has diabetes with a lesion on the foot, is taking medicines that suppress the immune system, or is a newborn. Call 115 (the emergency number in Vietnam) if there is a high fever with drowsiness, or the infected skin is spreading rapidly over a few hours.
People with diabetes and anyone with a weakened immune system should be seen sooner: according to CDC, a bacterial infection on top of a fungal one can cause serious illness in this group. Be seen by a doctor within 24–72 hours, and stop applying things yourself, if:
- The lesion is on the scalp, with hair loss in patches, or on the nails
- The patch is on the face, around the eye, in the genital area, or over a large area of skin
- You have applied something and the patch is no better, or is widening
- You are not sure whether this is ringworm or eczema, psoriasis or scabies — the treatments pull in opposite directions
- The patient is pregnant, or an older person confined to bed
What can be done at home, and when a medical facility is needed
Ringworm is not an emergency, but most cases should be looked at in person once. At home, Y Te Xanh (GreenCare) doctors and nurses can: review the tube you have been using, assess the lesion, and care for broken skin as prescribed. Ringworm of the scalp and of the nails has to go to a medical facility for testing.
Source: CDC — keep skin clean and dry, and see a healthcare professional if you suspect ringworm of the scalp or nails. Citing CDC here does not imply that CDC endorses Y Te Xanh or our services.
Need personalised advice for your loved one? Call our hotline 094 368 81 15 (24/7) — calling to ask a question or to book costs nothing. GreenCare has doctors who come to examine, nurses who carry out doctor's orders (injections, infusions, dressing changes), remote consultation by video call, and a review of the medicines you are taking; an in-depth remote consultation, or any one after the first, is a paid service. For children we take examination and acute care only — not long-term care at home, and not newborns or expectant mothers. We confirm we have staff in your area and provide transparent pricing before we begin.
Sources
- CDC — Ringworm Basics
