Editing Rash (section)

== Differential diagnosis ==
Common causes of rashes include:
* Food [[allergy]]
* [[Medication]] [[side effects]]<ref name = Davis2017>{{cite web | title = Eszopiclone | publisher = F.A. Davis | date = 2017 | access-date = April 15, 2017 | url = http://davisplus.fadavis.com/3976/meddeck/pdf/eszopiclone.pdf | archive-date = October 8, 2017 | archive-url = https://web.archive.org/web/20171008100344/http://davisplus.fadavis.com/3976/meddeck/pdf/eszopiclone.pdf | url-status = dead }}</ref><ref name =zolDavis2017>{{cite web | title = Zolpidem | publisher = F.A. Davis | url = http://davisplus.fadavis.com/3976/meddeck/pdf/zolpidem.pdf | access-date = April 15, 2017 | archive-date = December 22, 2017 | archive-url = https://web.archive.org/web/20171222105509/https://davisplus.fadavis.com/3976/meddeck/pdf/zolpidem.pdf | url-status = dead }}</ref>
* [[Anxiety]]
* Allergies, for example to food, dyes, medicines, insect stings, metals such as zinc or nickel; such rashes are often called [[hives]].
* Skin contact with an [[Irritation|irritant]]
** [[Fungal infection in animals|Fungal infection]], such as [[ringworm]]
** [[Balsam of Peru]]<ref name="google1">{{cite book|url=https://books.google.com/books?id=dQBAzfyCeQ8C&q=%22balsam+of+peru%22+rash&pg=PA735 |title=Fisher's Contact Dermatitis |first=Alexander A.|last=Fisher |year=2008 |publisher=PMPH-Usa |isbn=9781550093780 |access-date=2014-04-24}}</ref>
* Skin diseases such as [[eczema]] or [[Acne vulgaris|acne]]
* Exposure to [[sun]] ([[sunburn]]) or [[heat]]
* [[Friction]] due to chafing of the skin
* [[Irritation]] such as caused by abrasives impregnated in clothing rubbing the skin. The cloth itself may be abrasive enough for some people
* [[Secondary syphilis]]
* Poor personal hygiene
Uncommon causes:
* [[Autoimmune disorder]]s such as [[psoriasis]]
* [[Lead poisoning]]
* [[Pregnancy]]
* Repeated scratching on a particular spot
* [[Lyme disease]]
* [[Scarlet fever]]
* [[COVID-19]] (see {{section link|Symptoms of COVID-19|Other}})

===Conditions===
{| class="wikitable"
|-
!  Skin disease !! Symptoms !! Usual area of body
|-
| [[Acne vulgaris]]
| Comedones, papules, pustules and nodules.
| Face, chest and back.
|-
| Acne [[rosacea]]
| Flushed appearance or redness.
| Cheeks, chin, forehead or nose.
|-
| [[Boil]]
| Painful red bump or a cluster of painful red bumps
| Anywhere
|-
| [[Cellulitis]]
| Red, tender and swollen areas of skin
| Around a cut, scrape or skin breach
|-
| [[Insect bite]]
| Red and/or [[itch]]y bumps on the skin
| Anywhere and can be sprinkled randomly
|-
| [[Erythema migrans]] / [[Lyme disease]]
| Expands over days or weeks to 5–70&nbsp;cm (median 16&nbsp;cm), circular or oval, red or bluish, may have an elevated or darker center, may have a central or ring-like clearing, may feel warm, not painful or itchy<ref name=CDC_Lyme_rashes>{{cite web |title=Lyme disease rashes and look-alikes |url=https://www.cdc.gov/lyme/signs_symptoms/rashes.html |website=Lyme Disease |publisher=Centers for Disease Control and Prevention |access-date=April 18, 2019 |archive-date=April 2, 2019 |archive-url=https://web.archive.org/web/20190402185303/https://www.cdc.gov/lyme/signs_symptoms/rashes.html |url-status=live }}</ref><ref name=lyme_rashes_uk>{{cite web | title = Lyme disease: erythema migrans | url = https://www.nice.org.uk/guidance/ng95/resources/lyme-disease-rash-images-pdf-4792273597 | website = Lyme disease NICE guideline [NG95] | publisher = National Institute for Health and Care Excellence | access-date = May 8, 2019 | archive-date = May 9, 2019 | archive-url = https://web.archive.org/web/20190509035408/https://www.nice.org.uk/guidance/ng95/resources/lyme-disease-rash-images-pdf-4792273597 | url-status = live }}</ref>
| [[Armpit]], [[groin]], [[Popliteal fossa|back of knee]], on the [[Torso|trunk]], under clothing straps, or in children's hair, ear, or neck<ref name=wright_2012>{{cite journal | vauthors = Wright WF, Riedel DJ, Talwani R, Gilliam BL | title = Diagnosis and management of Lyme disease | journal = American Family Physician | volume = 85 | issue = 11 | pages = 1086–93 | date = June 2012 | pmid = 22962880 | url = http://www.aafp.org/afp/2012/0601/p1086.html | archive-url = https://web.archive.org/web/20130927081243/http://www.aafp.org/afp/2012/0601/p1086.html | df = dmy-all | url-status = live | archive-date = 27 September 2013 }}</ref><ref name=NEJM2014>{{cite journal | vauthors = Shapiro ED | title = Clinical practice. Lyme disease | journal = The New England Journal of Medicine | volume = 370 | issue = 18 | pages = 1724–1731 | date = May 2014 | pmid = 24785207 | pmc = 4487875 | doi = 10.1056/NEJMcp1314325 | url = http://portal.mah.harvard.edu/templatesnew/departments/MTA/Lyme/uploaded_documents/NEJMcp1314325.pdf | archive-url = https://web.archive.org/web/20161019142422/http://portal.mah.harvard.edu/templatesnew/departments/MTA/Lyme/uploaded_documents/NEJMcp1314325.pdf | archive-date = 19 October 2016 }}</ref>
|-
| [[Allergic reaction]]
| Irregular, raised or flat red sores that appeared after taking medicine/drugs or eating certain foods
| Anywhere
|-
| [[Hidradenitis Suppurativa]]
| Deep sebum filled cystic condition of apocrine gland overstimulation, caused by many internal and external factors e.g., stress, toxic environmental overload and immune impairment.
| See Hidradenitis.
|-
| [[Hives]]
| Bumps formed suddenly
| Anywhere but usually first noticed on face
|-
| [[Seborrheic dermatitis]]
| Bumps and swelling
| Near glands
|-
| [[Cradle cap]]
| Dry, scaly skin
| Scalp of recently born babies
|-
| [[Irritant contact dermatitis]]
| Red, itchy, scaly, or oily rash
| Eyebrows, nose, edge of the scalp, point of contact with jewellery, perfume, or clothing.
|-
| [[Urushiol-induced contact dermatitis|Allergic Contact Dermatitis]] caused by [[poison ivy]], [[Toxicodendron diversilobum|poison oak]], [[sumac]], or [[Balsam of Peru]]<ref name="google1"/>
| Red, itchy, scaly or oily rash; can also be weeping or leathery.
| Anywhere that came in contact with the irritant either directly or via transfer (e.g. from contaminated clothing.)
|-
| [[Allergic purpura]]
| Small red dots on the skin, or larger, bruise-like spots that appeared after taking medicine
| Anywhere
|-
| [[Pityriasis Rosea]]
| Started with a single scaly, red and slightly itchy spot, and within a few days, did large numbers of smaller patches of the rash, some red and/or others tan
| Chest and abdomen
|-
| [[Dermatitis herpetiformis]]
| Intensely itchy rash with red bumps and blisters
| Elbows, knees, back or buttocks
|-
| [[Erythema nodosum]]
| Large red bumps that seem to bruise and are tender to touch
| Anywhere
|-
| [[Psoriasis]]
| White, scaly rash over red, flaky, irritated skin
| Elbows and knees
|-
| [[Erythema multiforme]]
| Red, blotchy rash, with "target like" hives or sores.
| Anywhere
|-
| [[Measles]]
| Red rash that is raised with a fever or sore throat.
| Usually starts first on the forehead and face and spreads downward.
|-
| [[Chickenpox]]
| Multiple blisters with a fever, cough, aches, tiredness and sore throat.
| Usually starts first on the face, chest and back and spreads downward.
|-
| [[Shingles]]
| Red blisters that are very painful and may crust
| Anywhere
|-
| [[Fifth Disease]]
| Started as a fever and then developed a bright red rash
| Cheeks
|-
| [[Warts]]
| Soft bumps forming that do not itch and have no other symptoms
| Anywhere
|-
| [[Ringworm]]
| Bald spot on the scalp or a ring of itchy red skin
| Anywhere
|-
| [[Syphilis]]
| Rash that is red but not itchy
| Palms of hands or soles of feet
|-
| [[Jock itch]], [[yeast infection]] or [[diaper rash]]
| Red itchy rash
| Groin
|-
| [[Tinea versicolor]]
| Light coloured patches
| Anywhere
|-
| [[Impetigo]]
| Crusted, tan-colored sores
| Near nose or lip
|-
| [[Scabies]]
| Bite-like sores that itch and spread intensely
| Usually start on hands or feet and spread everywhere
|-
| [[Rocky Mountain spotted fever]]
| A fine rash with a fever and headache
| Usually start on arms and legs including the hands and feet
|-
| [[Lupus erythematosus]]
| A butterfly rash with achy joints
| Forehead and cheeks
|-
| [[Jaundice]] or sign of [[hepatitis]]
| Yellowish
| Skin, whites of eyes and mouth
|-
| [[Bruise]]
| Blue or black area after being hit
| Anywhere
|-
| [[Actinic keratoses]]
| Scaly, pink, gray or tan patches or bumps
| Face, scalp or on the backs or the hands
|-
| [[Keloid]] or [[hypertrophic scar]]
| Scar that has grown larger than expected
| Anywhere
|-
| [[Lipoma]]
| Soft or rubbery growth
| Anywhere
|-
| [[Milium (disease)|Milia]]
| Many white spots
| On the face of a baby
|-
| [[Molluscum]] or contagiosum
| Small, firm, round bumps with pits in the center that may sit on tiny stalks
| Anywhere
|-
| [[Scarlet fever]]
| Becomes confluent and forms bright red lines in the skin creases of the neck, armpits and groins ([[Pastia's lines]])
| Face, chest and back, whole body, armpits, inside elbows, groins
|-
| [[Sebaceous cyst]]
| Bump with a white dome under the skin
| Scalp, nape of the neck or upper back
|-
| [[Skin tag]]
| Soft, fleshy growth, lump or bump
| Face, neck, armpits or groin
|-
| [[Xanthelasma]]
| Yellow area under the skin
| Under eyelids
|-
| [[Melanoma]]
| Dark bump that may have started within a mole or blemish, or, a spot or mole that has changed in color, size, shape or is painful or itchy
| Anywhere
|-
| [[Basal cell carcinoma]]
| Fleshy, growing mass
| Areas exposed to the sun
|-
| [[Squamous cell carcinoma]]
| Unusual growth that is red, scaly or crusted
| Face, lip or chin
|-
| [[Kaposi's sarcoma]]
| Dark or black raised spots on the skin that keep growing or have appeared recently
| Anywhere
|-
| [[Erythema annulare centrifugum]] (EAC)
| Pink-red ring or bullseye marks
| Anywhere
|}