Most of us have dealt with some kind of skin rash at one point or another. Maybe it was a patch of eczema, an allergic reaction to a new skincare product, heat rash after a hot day, or an itchy bite that disappeared almost as quickly as it arrived.
But every now and then, a rash looks completely different from anything we’ve seen before.
Some form perfect circles. Others look like lace, tree branches, targets, bruises or even toasted skin. And while many unusual-looking rashes are harmless, others can occasionally be an outward sign that something else is happening inside the body.
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That’s why I think it’s useful to know what some of the more distinctive skin rashes can look like.
See also: Simple and Effective Skin Rash Treatment Options >
One important point before we get started: a rash can’t reliably be diagnosed from appearance alone. Many different conditions can look remarkably similar, and skin colour can also affect how redness, inflammation and discoloration appear.
This article is intended as a general guide rather than a way to diagnose yourself.
1. Pityriasis Rosea – The “Christmas Tree” Rash
Pityriasis rosea is one of those skin conditions that can look rather alarming when you first see it, even though it’s generally harmless.
It often begins with a single larger oval patch known as a herald patch. Several days or weeks later, lots of smaller patches may appear over the torso.
On the back, these patches sometimes follow the natural lines of the skin, creating a pattern that has traditionally been described as resembling the branches of a Christmas tree.
The American Academy of Dermatology says pityriasis rosea commonly lasts around six to eight weeks, although individual cases vary. It isn’t considered contagious.
What it can look like
You may notice:
One larger oval patch appearing first
Multiple smaller oval or round patches later
Fine scaling around the edges
Patches concentrated on the chest, stomach or back
Mild to significant itching in some people
One reason it’s worth getting checked is that pityriasis rosea can resemble fungal infections, eczema and psoriasis.
In most cases it clears without specific treatment.
2. Erythema Multiforme – The Target Rash
This is probably one of the most visually distinctive rashes on the list.
Erythema multiforme can cause circular spots with rings of colour around them, giving the lesions a bull’s-eye or target-like appearance.
The rash frequently begins on the hands or feet before spreading further across the body. Some people experience itching or burning.
Infections are a common trigger, although certain medicines can also be associated with the condition. Mild erythema multiforme frequently improves within two to four weeks.
What it can look like
Look for:
Round, raised spots
Concentric rings
A darker centre
Blistering in some lesions
Spots appearing symmetrically on hands, arms, feet or legs
More severe cases can involve painful sores inside the mouth, around the lips, eyes or genital area and require medical evaluation.
A bull’s-eye rash isn’t automatically erythema multiforme either. Other conditions, including Lyme disease, can produce expanding or ring-like rashes, so this is definitely one I’d want professionally assessed rather than trying to identify from photographs online.
3. Livedo Reticularis – The Lace-Like Rash
Have you ever looked down at your legs and noticed a purple, red or blue network running across your skin?
This type of pattern may be livedo reticularis.
Rather than looking like ordinary spots, it produces a mottled, web-like or lace-like pattern. It commonly affects the legs and can become more obvious in cold temperatures.
The pattern develops because of changes in blood flow through small blood vessels close to the skin.
What it can look like
Typical characteristics include:
Purple-red or blue mottling
A lace or fishing-net pattern
Pale skin inside the coloured network
Greater visibility when you’re cold
Most commonly appearing on the legs
Sometimes the pattern disappears once the skin warms again.
Persistent livedo, however, can occasionally occur alongside vascular, autoimmune or other systemic conditions, which is why an unexplained pattern that doesn’t disappear deserves medical attention.
4. Toasted Skin Syndrome
This one has one of the stranger names in dermatology.
Toasted skin syndrome, medically known as erythema ab igne, develops after repeated exposure to relatively low levels of heat.
We’re not talking about a burn from touching something extremely hot. Instead, the skin is repeatedly warmed over a long period.
Possible culprits include:
Heating pads
Heated blankets
Hot-water bottles
Space heaters
Car-seat heaters
A hot laptop repeatedly resting on the same area
Over time, a reddish or brown net-like pattern can develop.
Cleveland Clinic notes that removing the heat source generally allows early cases to improve, although darker pigmentation can persist.
The important clue here is usually where the rash appears. If a mysterious patterned patch has developed exactly where your heating pad sits every evening, the connection may suddenly become much more obvious.
5. Shingles – The One-Sided Blistering Rash
Shingles isn’t especially rare, but its distinctive appearance is worth knowing because early treatment can be important.
It happens when the virus responsible for chickenpox becomes active again later in life.
Before the rash appears, you may experience:
Tingling
Burning
Pain
Itching
Unusual skin sensitivity
Then clusters of small fluid-filled blisters develop.
One of the biggest clues is that shingles typically affects one side of the body and follows the path of a nerve.
The CDC says it often forms a stripe around one side of the torso or appears on one side of the face and usually doesn’t cross the body’s midline.
Why shingles deserves prompt attention
Shingles can occasionally cause complications, especially when it affects the face or eyes. Persistent nerve pain known as postherpetic neuralgia is its most common complication.
If you suspect shingles, particularly around your eye or face, contact a healthcare professional promptly.
6. Fixed Drug Eruption – The Rash That Keeps Returning to Exactly the Same Spot
This is a fascinating one.
A fixed drug eruption is a reaction to medication that repeatedly appears in the same location whenever the triggering medicine is taken.
You might notice a circular or oval red, purple or dark patch that fades but leaves discoloration behind.
Then months later you take the same medication — and the rash appears again in precisely the same spot.
That repeating pattern can provide a major clue.
The CDC includes fixed drug reactions among conditions that may resemble other circular rashes.
If you notice a recurring rash after starting or taking medication, don’t simply stop prescribed medication without advice. Contact your doctor, pharmacist or prescribing clinician so they can assess the possible reaction.
7. Granuloma Annulare – A Ring That Isn’t Ringworm
Circular rashes often immediately make people think of ringworm.
But not every ring-shaped rash is fungal.
Granuloma annulare causes small bumps arranged in rings or circles. Unlike classic ringworm, the affected area often isn’t particularly scaly.
It commonly develops on areas including:
Hands
Feet
Elbows
Ankles
Because the lesions can be circular, it’s easy to mistake granuloma annulare for fungal ringworm, particularly when you’re relying on online photographs.
The CDC specifically includes granuloma annulare among rashes that can resemble the expanding rash associated with Lyme disease.
Again, the lesson here is that shape alone doesn’t provide a diagnosis.
8. Necrobiosis Lipoidica – Shiny Patches on the Lower Legs
Necrobiosis lipoidica is much less familiar to most people.
It generally appears on the lower legs and can gradually develop into yellowish, reddish-brown or purplish patches.
Over time the centre may become thin and shiny, sometimes making the blood vessels beneath the skin particularly visible.
Occasionally the skin can break down and form ulcers.
Cleveland Clinic lists necrobiosis lipoidica among uncommon skin conditions and notes that the rash typically affects the lower legs and may develop sores.
Because persistent shin lesions can have many causes, an unexplained patch that changes, becomes painful or develops an ulcer should be examined professionally.
9. Cold-Induced Mottling
Not every dramatic-looking skin change means you have a disease.
Sometimes cold temperatures cause blood vessels near the skin to narrow temporarily, producing a purple or blue marbled pattern.
You might notice it particularly on your legs after:
Sitting in a cold room
Getting out of a swimming pool
Spending time outdoors in winter
This temporary mottling is sometimes called cutis marmorata.
DermNet explains that cold-related mottling normally improves as the body warms up.
The important distinction is whether the colour disappears when you warm up.
If you’re regularly seeing a strong net-like pattern that doesn’t improve with warmth — particularly alongside pain, ulcers or other symptoms — mention it to your doctor.
10. Heat or Sun-Induced Hives
We normally think of allergies as reactions to food, pollen, cosmetics or medication.
But some people develop hives in response to physical triggers.
These can include:
Cold
Heat
Sunlight
Pressure
Exercise
Even water in extremely rare cases
The resulting rash can consist of itchy raised welts that appear quickly after exposure.
Cleveland Clinic notes that unusual physical triggers including sunlight, cold and water can provoke allergic-type reactions in some people.
If hives repeatedly appear under very specific circumstances, keeping a diary of what happened immediately beforehand can be surprisingly useful when discussing the problem with a doctor or allergist.
11. COVID-Associated Skin Changes
COVID-19 became associated with some rather unexpected skin changes, particularly earlier in the pandemic.
One of the best-known was the development of swollen or discoloured toes sometimes nicknamed “COVID toes.”
Research over subsequent years has shown that chilblain-like lesions aren’t exclusive to COVID and can occur with other viral infections as well.
Cleveland Clinic’s updated 2026 guidance describes chilblain-like skin lesions and other rashes as uncommon complications that may occur alongside viral illnesses.
This is a good reminder that infections don’t always announce themselves with the symptoms we expect.
Sometimes the skin provides one of the first clues that the immune system is responding to something elsewhere in the body.
12. Orf – The Rash You Can Pick Up From Sheep or Goats
This is definitely one of the more unusual possibilities.
Orf is a viral skin infection that humans can catch through contact with infected sheep or goats.
It usually causes a distinctive blister or lesion, commonly on the hands or arms after handling an infected animal.
The NHS says the lesion generally clears by itself in approximately six weeks.
People who work with livestock are much more likely to encounter it.
Interestingly, orf can occasionally trigger another rash — including the target-shaped lesions of erythema multiforme.
So if you’ve been handling sheep or goats and suddenly develop an unusual hand lesion, that bit of background information could be extremely useful to your doctor.
Why Skin Rashes Can Be So Difficult to Identify
One of the biggest problems with rashes is that very different conditions can look remarkably similar.
For example, a circular rash might potentially be associated with:
Ringworm
Granuloma annulare
Pityriasis rosea
Lyme disease
A medication reaction
Similarly, a blistering rash might potentially be caused by shingles, dermatitis, infection, an allergic reaction or something else entirely.
Even medical professionals sometimes need additional information before reaching a diagnosis.
They may consider:
Where did the rash start?
Location can provide important clues.
Does it itch, burn or hurt?
Painful and itchy rashes often have different causes.
How quickly did it appear?
A rash that appears within minutes is very different from one gradually developing over several weeks.
Have you started any new medication?
Medication reactions are an important possibility.
Have you been ill recently?
Viruses and other infections frequently trigger skin reactions.
Have you travelled or been bitten by an insect or tick?
Exposure history matters.
Has anything repeatedly touched or heated that area?
Think jewellery, skincare products, laundry detergent, heating pads and work equipment.
The pattern is only one piece of the puzzle.
How Rashes Can Look Different on Different Skin Tones
Descriptions such as “red rash” can sometimes be misleading.
Inflammation doesn’t necessarily look bright red on everyone.
Depending on your natural skin tone, an inflammatory rash may appear:
Red
Pink
Purple
Grey
Brown
Darker than the surrounding skin
Texture, swelling, warmth, pain and itching may therefore be just as useful as colour when noticing changes.
If you’re comparing your skin to pictures online, try to look for medical resources that show conditions across several skin tones rather than relying on a single photograph.
When Should You Worry About a Rash?
Most rashes aren’t medical emergencies.
But there are situations where I wouldn’t wait around to see what happens.
The American Academy of Dermatology recommends medical attention when a rash:
Covers much of the body
Spreads rapidly
Is painful
Produces blisters or open sores
Occurs alongside fever or illness
Involves the eyes, mouth, lips or genital area
Possible signs of infection include increasing pain, swelling, warmth, pus, crusting, an unpleasant smell or fever.
Seek emergency medical help if:
A rash is accompanied by difficulty breathing or swallowing, or swelling of the lips or eyes.
Those symptoms may indicate a severe allergic reaction or another serious medical problem.
What to Do When a Mysterious Rash Appears
If something unusual suddenly appears on my skin, I’d resist the temptation to immediately try five different creams.
Instead, I’d start by documenting it.
Take a clear photograph in natural light.
Then photograph it again over the next few days.
Make a note of:
When it appeared
Whether it’s spreading
Whether it itches or hurts
Any recent illness
New medications
New supplements
Skincare products
Laundry products
Foods
Travel
Insect or tick bites
Animal contact
Heat exposure
These details can be enormously helpful if you eventually see a doctor or dermatologist.
And avoid endlessly comparing your rash with photographs online. Dermatology pictures can point you towards possibilities, but they can also convince you that one condition is ten different things within about five minutes.
Frequently Asked Questions
1. Can stress cause unusual skin rashes?
Stress can worsen several skin conditions and may contribute to hives or flare-ups in people who already have inflammatory skin conditions. However, don’t automatically assume that an unexplained rash is caused by stress.
Persistent or unusual changes should still be assessed.
2. Why has my rash appeared suddenly?
Possible triggers include infection, medication, allergies, irritants, insect bites, heat, cold, immune reactions and numerous skin conditions.
The timing of recent changes can provide useful clues.
3. Why does my rash look like a net?
Net-like or lace-like skin changes can occur with conditions including livedo reticularis and prolonged heat exposure.
Cold-related mottling often improves when your skin warms, whereas persistent changes warrant medical advice.
4. Why does my rash look like a bull’s-eye?
Target-like lesions are characteristic of erythema multiforme, but circular or expanding lesions can have several causes.
A bull’s-eye appearance shouldn’t be used to diagnose a condition from appearance alone.
5. Is every circular rash ringworm?
No.
Ringworm is only one possible cause of a circular rash. Granuloma annulare, pityriasis rosea, medication reactions and several other conditions can also produce circular lesions.
6. Should I put steroid cream on an unexplained rash?
Not necessarily.
Using the wrong treatment can disguise symptoms or sometimes make certain infections worse. If you don’t know what’s causing a persistent rash, getting advice from a pharmacist, doctor or dermatologist is usually a better first step.
7. Can medication cause a rash even if I’ve taken it before?
Yes. Drug reactions don’t necessarily happen the first time you take a medication.
If you think a prescription medicine may be causing a reaction, contact a healthcare professional rather than stopping important medication without medical guidance.
8. When should I see a dermatologist?
Arrange an appointment if your rash is unexplained, persistent, repeatedly returning, changing significantly or interfering with everyday life.
You should seek more urgent medical attention when the rash is painful, rapidly spreading, blistering, associated with fever or affecting sensitive areas such as your eyes or mouth.
The Bottom Line
Our skin can produce some incredibly strange patterns.
A rash might resemble lace, targets, rings, bruises or tree branches. Sometimes those patterns provide a useful clue about what’s happening — but they’re rarely enough to provide a diagnosis on their own.
Conditions such as pityriasis rosea and cold-related mottling may disappear without treatment, whereas shingles, medication reactions and certain vascular or inflammatory rashes deserve medical evaluation.
So instead of asking only “What does this rash look like?”, I think the more useful questions are:
When did it appear?
What was happening beforehand?
Is it spreading?
Does it hurt?
And do I have any other symptoms?
The skin is surprisingly good at telling us when something has changed. We just shouldn’t rely on appearance alone to decide exactly what it’s trying to tell us.
This article is for general informational purposes only and isn’t intended to diagnose or treat a medical condition. Seek professional medical advice for a new, unexplained, persistent or concerning rash.
Resources
American Academy of Dermatology (AAD) – Rash 101: When to Seek Medical Treatment
https://www.aad.org/public/everyday-care/itchy-skin/rash/rash-101
Useful for warning signs such as rapidly spreading, painful, blistering or widespread rashes.
Centers for Disease Control and Prevention (CDC) – Lyme Disease Rashes
https://www.cdc.gov/lyme/signs-symptoms/lyme-disease-rashes.html
Includes photographs and information about Lyme disease rashes, fixed drug eruptions, granuloma annulare, ringworm and other lookalike conditions.
Centers for Disease Control and Prevention (CDC) – Clinical Features of Shingles
https://www.cdc.gov/shingles/hcp/clinical-signs/index.html
Explains the characteristic one-sided, blistering shingles rash and its typical progression.
Mayo Clinic – Pityriasis Rosea: Symptoms and Causes
https://www.mayoclinic.org/diseases-conditions/pityriasis-rosea/symptoms-causes/syc-20376405
Covers the herald patch, pine-tree or “Christmas tree” pattern, itching and typical duration of pityriasis rosea.
Cleveland Clinic – Toasted Skin Syndrome (Erythema Ab Igne)
https://my.clevelandclinic.org/health/diseases/toasted-skin-syndrome
Explains the unusual net-like rash caused by repeated exposure to heating pads, laptops, heated blankets and other heat sources.
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