Diagnose My Skin Rash

The "Diagnose My Skin Rash" page gives a guide to the different types of rash that you may have and makes it easy to identify your rash. There are photos of many rashes to help you.

The information on this page gives information for all ages. However, if you have a newborn baby with a rash, first look at the Infant Skin Rash page.

To identify a skin rash you need to know about its:

  • color
  • is it flat or raised?
  • is it scaly or not?
  • is it filled with fluid or not

You don't need to know what the rash is to use this page, you just need to know what it looks like!

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The links on the "Diagnose My Skin Rash" page are for pages specifically written on those topics with children in mind.

First, decide if your rash is:

To know when to seek medical help, click here

Once you have decided what type of rash it is, you can see what types of rashes cause that type of rash and for many rashes, you can view a photo. It makes it easy to diagnose my skin rash once you can describe it.

For childhood rashes, you can click directly on the link to go to the page on this site that has more information on that rash.

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Red and Non-Scaly Rash with Rounded Top

To diagnose my skin rash if it is red and raised with a rounded top:

insect bites rashInsect bites
strawberry nevus baby skin rashStrawberry Nevus
basal-cell-carcinomaBasal cell carcinoma
erythema nodosum rashErythema nodosum
  • insect bite - usually on exposed skin and itchy. You may see a red central "bite" mark
  • strawberry nevus (hemangioma) - bright red present at or shortly after birth. Read more
  • inflamed epidermoid cyst - an epidermoid cyst is a smooth round lump just below the surface of the skin. Often small (pea-sized) and occurs on face, neck, chest and back. When inflamed it looks red
  • erythema nodosum - painful red tender lumps most often on the shins. Can be associated with other conditions (including infection) and medications
  • nodular basal cell carcinoma (BCC) - slow growing locally invasive tumors of the skin that may be a few millimetres to a few centimetres in diameter. They can occasionally bleed or ulcerate. They occur on skin exposed to the sun. BCC is rarely a threat to life

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Red and Non-Scaly Rash that is Flat

To "diagnose my skin rash" if it is red and non-scaly, consider:

  • toxic erythema - common harmless red rash in newborn babies. Read more
  • measles and other erythematous rashes - see the main child skin rash page if your child has a red rash. The most common cause will be a virus
  • urticaria - an allergic rash with wheals (hives). It is very itchy. Read more
  • erythema multiforme - self-limiting red rash with multiple forms, including red spots, welts and occasionally blisters. There is often what is called a target lesion - this looks a bit like a bulls eye on a dart board. This rash is usually caused by infection, particularly with herpes or Mycoplasma. It may involve mucus membranes, such as mouth and lips, eyes and genital areas
  • cellulitis - inflammation of the skin making it warm and tender to touch - requires antibiotics for treatment. Often as a result of a laceration or other break in the skin - like the photo
  • purpura or petechiae - purple or red rash that doesn't blanch on pressure. This can be as a result of a serious infection or illness so needs attention. Read more
  • lupus - characteristic butterfly rash across the cheeks and upper nose. Very sensitive to sunlight
  • reaction to medication - can look like any of the above red rashes
  • Stevens Johnson Syndrome - this serious skin problem can start with a red / purple rash that then blisters or peels. It is usually associated with involvement of the mouth and/or eyes. It can be a reaction to medication. See your doctor for any rash that causes large blisters or peeling of the skin leaving it looking raw
measlesTrunk skin rashMeasles
erythema toxicum skin rashToxic Erythema
urticaria close up rashUrticaria
cellulitis skin rashCellulitis
petechiae purpura skin rashPetechiae and purpura
erythema multiforme skinErythema multiforme

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Red and Scaly

If you are asking "diagnose my skin rash" and the rash is red and scaly, the answer may be:

eczema baby leg skinEczema
Tinea capitis rashRingworm head
Tinea corporis rashRingworm body
  • eczema - a dry itchy rash. Read more
  • candidiasis - caused by a yeast infection and also known as thrush. Often seen in babies in the diaper (nappy) area or the mouth. Read more
  • ringworm - tinea - fungal infection usually with a circular area with scales in the middle. On the head, you get bald patches with hair that breaks easily. Head infections (tinea capitis) require oral treatment whereas body infections (tinea corporis) can be treated with creams
  • seborrheic dermatitis - greasy rash especially in infants and after puberty affecting face and scalp (where it is known as cradle cap). Read more
  • psoriasis - red scaly patches on skin (can look silvery). Can also affect the joints and nails
  • scabies - an intensely itchy rash that usually starts in the finger webs caused by a parasite. This is a very contagious rash and usually the whole family need treatment
  • pityriasis rosacea - seen in 10-35 year olds. Starts with a large pink patch on chest or back and then within a week or two there are more pink patches on arms, legs, chest and back (often in a Christmas tree pattern). Worse after exercise or bathing. Can be itchy
  • lichen planus - shiny flat-topped bumps anywhere on the body. Characteristically, purple lumps of various shapes that itch. Usually in 30-70 year olds. Cause is unknown
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Psoriasis skin rashPsoriasis
scabies skin rashScabies
seborrheic dermatitis rashSeborrheic Dermatitis

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Fluid Filled

impetigo skin rashImpetigo
chicken pox rashChickenPox
cold sore lip rashHerpes

If you want to diagnose my skin rash and it is fluid filled with clear fluid, it might be:

  • herpes simplex - blisters usually on corner of mouth or lips. Read more
  • varicella zoster (chickenpox) - A common childhood infection with spots that become little vesicles (blisters) and then crust over. Read more
  • dermatitis herpetiformis - very itchy chronic rash (usually in adults) with bumps and blisters on elbows, knees, back and buttocks in a symmetrical distribution. Linked with gluten intolerance
  • pompholyx - a type of eczema that affects the hands and occasionally the feet. First the skin blisters (these are very itchy) and then the skin peels off and is very dry
  • impetigo - commonly called school sores, these occur on the face and have golden crusts. Read more
  • contact dermatitis - irritation of the skin due to contact with foreign substances. It often causes a red itchy rash which may blister
  • erythema multiforme - self-limiting red rash with multiple forms, including red spots, welts and occasionally blisters. Usually secondary to infection particularly herpes and Mycoplasma. May involve the mouth, lips, eyes and genital region in more severe forms
  • pemphigoid and pemphigus - Usually occurs in older people. These are tense blisters. There is an underlying problem in the immune system (usually autoimmune)
  • Stevens Johnson Syndrome - this serious skin problem can start with a red / purple rash that then blisters or peels. It is usually associated with involvement of the mouth and/or eyes. It is usually a reaction to medication. See your doctor for any rash that causes large blisters or peeling of the skin leaving it looking raw

To diagnose my skin rash if the fluid filled rash has non-clear fluid (like pus), the rash might be:

folliculitis back rashBacterial folliculitis
  • acne - includes white heads, black heads and pimples and is associated with blocked sweat glands
  • bacterial folliculitis - inflammation of the hair follicles causing pus-filled pimples at the base of the hair shaft. Can be a complication of too many hot tubs - if so, wipe with vinegar and this may help is the cause is Pseudomonas. Otherwise Staphylococcus is the likely organism and an antibiotic cream is needed
  • bacterial infection - often associated with a yellow crust or pus

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Raised and Solid and Non-red

To diagnose my skin rash if it is raised but not red, it might be:

seborrheic keratosis rashSeborrheic keratosis
milia skin rashMilia
molluscum contagiosum leg rashMolluscum contagiosum
  • wart - small growth with rough surface, usually on hands or feet
  • corn - thickened skin on foot in an area of pressure
  • actinic keratosis - occurs usually on the face in elderly people after sun exposure. Is flat and scaly. It is also known as solar keratosis
  • seborrheic keratosis - wart-like growths which can be a variety of colors. Usually painless and in people over 40 years of age. No treatment is required unless there are symptoms - if so, cryotherapy may be useful
  • epidermoid cyst - smooth round lump just below the surface of the skin. Often small (pea-sized) and occurs on face, neck, chest and back
  • skin cancer - basal and squamous cell carcinoma - in adults. Bump or red scaly patch in skin exposed to the sun that bleeds easily and doesn't heal well
  • lipoma - benign growth made up of fatty tissue which is soft, mobile under the skin and painless. It is usually skin colored
  • molluscum contagiosum - infection causing pearl like lumps with a central dimple caused by the pox virus. Read more
  • milia - tiny white bumps on forehead, nose and cheeks of newborn babies caused by blocked sweat ducts. Read more
  • sebaceous gland hyperplasia - harmless small cream or white colored solid lumps usually on the face

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White and Flat

Want to diagnose my skin rash that is white and flat - here are some causes:

hypopigmentation chicken pox skin rashHypopigmentation
  • pityriasis alba - usually seen in children is seen in areas of inflammation where the skin loses its pigment and becomes dry and flaky. Usually has disappeared by adulthood
  • pityriasis versicolor (tinea versicolor) - flaky discolored patches mainly on chest and back. Can be a variety of colors including white, pink or light brown. More common in hot climates
  • vitiligo - loss of pigment in the skin so it looks completely white usually with an irregular border. Flat and non-painful. More noticeable in darker skinned people
  • hypopigmentation after an inflammatory response - temporary loss of skin pigment after an inflammatory condition such as eczema

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Brown and Flat

Want to diagnose my skin rash when it is brown and flat, here are some causes:

freckle rashFreckle
mole rashMole

freckle - small spots of melanin pigment (brown)

  • mole - colored spot on skin that can be flat or raised, round or oval. Can initially look like a freckle but it generally darker in color
  • cafe-au-lait patch - benign colored patches that look a light brown (like coffee with milk) and can be associated with other diseases (eg. in neurofibromatosis there are more than 5 large cafe-au-lait patches). More frequent in African-American or Afro-Caribbean populations
  • hyperpigmentation - darker areas of skin often seen after inflammation, with some diseases or medication
  • melanoma - most have a black-blue area with irregular border. They increase in size or change color or shape. They are the most serious form of skin cancer
  • giant nevus (birthmark) - large moles usually present from birth and hairy. Usually removed surgically as there is a risk of them developing cancer especially if they are large (more than 20 cm in diameter)

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Broken Blisters

If you are asking "diagnose my skin rash" and the rash started as blisters that have now broken, it could be serious as the skin is an important barrier to infection, so anytime there is widespread loss of skin, there can be complications.

scalded skin syndrome child skin rashScalded Skin Syndrome
burns face rashBurns to face
SJS skin rashStevens Johnson Syndrome
  • scalds and burns - it is usually obvious what has caused these because of the history
  • scalded skin syndrome - caused by a blood infection with Staphylococcal aureaus infection. The rash looks like scalded skin from boiling water or steam but there have been no burns or scalds and your child or you will be sick. This condition requires urgent medical attention and antibiotics
  • Stevens-Johnson Syndrome - this is a medical emergency. The usual cause is a reaction to drugs. The usual course is that you feel unwell with fever and aches, then develop a rash. The rash starts off as red rash that is tender to touch and painful. Blisters may develop that then break often leaving large areas of uncovered skin. There is also involvement of the mucous membranes, so the mouth and lips, eyes and genital areas.

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Remember the links on the "Diagnose My Skin Rash" page give more detailed information on those rashes in children.


When to Seek Medical Attention

See your doctor urgently for any rash that causes:

  • large blisters or peeling of the skin leaving it looking raw
  • fevers and general unwellness
  • serious involvement of the mouth, eyes or genital region
  • when you very unwell or you are very worried about your rash

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References for "Diagnose My Skin Rash"

  • Lynch P, Edminster SC. Dermatology for the Nondermatologist: A Problem-Oriented System. Ann Emerg Med. 1984; 13(8):603-606
  • DermNet NZ

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To go to the main Skin Rash page, click here

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Diagnose my skin rash last reviewed 15 October 2011

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Dr Maud MD

Dr Maud MD (MBChB, FRACP, FRCPCH), a specialist pediatrician, provides health information and medical advice for parents of babies and toddlers. Read more about Dr Maud.



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