Skin
Spreading circular rash
A round or ring-shaped patch on the skin that spreads outwards, which most often comes from a fungal infection or eczema, but can occasionally be the bull's-eye rash of Lyme disease after a tick bite.
Education and reference only. This explains the common causes of spreading circular rash and the warning signs that need urgent help, in plain language — it is not a diagnosis or a substitute for advice from a clinician. If you feel very unwell or are worried, seek medical help.
Quick answer
What is spreading circular rash?
A circular or ring-shaped rash on the skin has several possible causes, and the way it looks and behaves helps tell them apart. A red, scaly, itchy ring with a clearer centre that slowly enlarges is most often a fungal-skin-infection such as ringworm, which despite its name is not a worm.
- Get urgent help: A spreading bull's-eye rash after a tick bite needs prompt treatment — see a doctor promptly, as this can be early Lyme disease. A widespread rash with fever and feeling very unwell, or a rash that does not fade when pressed under a glass — call 999.
- Self-care: If a circular rash is mild, itchy and scaly and you suspect a fungal infection, keep the area clean and dry, avoid scratching, and do not share towels, bedding or clothing, as ringworm is contagious.
About spreading circular rash
A circular or ring-shaped rash on the skin has several possible causes, and the way it looks and behaves helps tell them apart. A red, scaly, itchy ring with a clearer centre that slowly enlarges is most often a fungal-skin-infection such as ringworm, which despite its name is not a worm. A round, dry, itchy patch can also be a form of eczema. The cause that matters most to recognise is a single, expanding circular rash, often with a paler centre giving a bull's-eye appearance, that develops days to weeks after a tick bite — this can be the characteristic early rash of lyme-disease and needs prompt treatment to prevent later problems. A hot, red, tender, spreading area that is not ring-shaped but enlarging may instead be cellulitis, a bacterial skin infection. Noting any tick bite, the speed of spread, and whether you feel unwell guides what to do.
When to get help
Call 999 or go to A&E if spreading circular rash comes with any of these warning signs:
- A spreading bull's-eye rash after a tick bite needs prompt treatment — see a doctor promptly, as this can be early Lyme disease.
- A widespread rash with fever and feeling very unwell, or a rash that does not fade when pressed under a glass — call 999.
- A hot, red, painful area that is spreading quickly, with fever — seek urgent help, as this can be a spreading skin infection.
- A tick bite followed by flu-like illness, joint pains, or facial drooping over the following weeks — see a doctor.
- A circular rash that is rapidly enlarging, blistering, or accompanied by feeling generally unwell.
When to see a doctor
See a doctor promptly if a circular rash develops days to weeks after a tick bite or possible exposure to ticks, especially if it is expanding or has a bull's-eye appearance, as early Lyme disease is best treated quickly. Seek same-day help for a hot, red, painful, rapidly spreading area with fever, which can mean a spreading skin infection. A mild, itchy, scaly ring that is not spreading fast can usually be assessed at a routine appointment, but should be seen if it does not improve, keeps spreading, or recurs. Any widespread rash with fever, or one that does not fade under a glass, is an emergency — call 999.
Not sure how urgent it is? It is always OK to call NHS 111 for advice, day or night.
What can cause it
Common causes of spreading circular rash
Spreading circular rash has many possible causes. Each links to a full, plain-language guide to that condition — what it is, how it's treated and when to seek help.
What helps
Self-care and what you can do
If a circular rash is mild, itchy and scaly and you suspect a fungal infection, keep the area clean and dry, avoid scratching, and do not share towels, bedding or clothing, as ringworm is contagious. Wash your hands after touching the rash and after handling pets, which can carry the infection. For a dry, eczema-type patch, regular moisturising and avoiding irritants help. The key safety point is to watch the rash: a single ring that keeps expanding after a tick bite, or a hot, painful, rapidly spreading red area, is not for self-care and needs to be seen. If you have been bitten by a tick, remove it promptly and cleanly, and keep an eye on the skin for several weeks.
Answers
Spreading circular rash: frequently asked questions
Is a ring-shaped rash always ringworm?
No. Ringworm (a fungal infection) is a common cause, but a round patch can also be eczema, and an expanding ring with a paler centre after a tick bite can be early Lyme disease. The history and how the rash behaves help tell them apart.
What does a Lyme disease rash look like?
It is typically a single, expanding circular rash, often with a paler centre giving a bull's-eye look, appearing days to weeks after a tick bite. It usually does not itch or hurt much. If you see this after a tick bite, see a doctor promptly.
How can I avoid spreading ringworm?
Keep the area clean and dry, avoid scratching, wash your hands after touching it, do not share towels, bedding or clothing, and treat affected pets. Ringworm is contagious but usually clears with treatment.
When is a circular rash an emergency?
A widespread rash with fever and feeling very unwell, or one that does not fade when pressed under a glass, is an emergency — call 999. A hot, rapidly spreading, painful red area with fever also needs urgent help.
Sources
Where this is drawn from
- NICE CKS: Lyme disease.
- Lyme Disease UK
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