What is a Rash?
Most of us consider a rash to be any abnormal change in skin color or texture. These changes may be due to a host of disturbances in the normal anatomy and even physiology of the skin. It can be due to inflammatory processes where the area is swollen, red, painful and feels hot to touch. Alternatively there may be excessive or reduced secretion of skin oils (sebum) and sweat. Destruction of skin, as is seen with an infection, scaling and oozing are some of the other disturbances that are collectively and sometimes incorrectly referred to as a rash.
What is an Itch?
Itching is a sensation that provokes a desire to scratch. It is not the same as pain or burning, although all of these sensations may be triggered by inflammation and similar chemicals like histamine. Itching is the body’s way of signalling that there is an irritant or potential threat on the skin surface. Specialized receptors are stimulated and this compels a person to scratch the area, thereby removing the irritant or threat. However, these itch receptors may also be stimulated by inflammatory chemicals like histamine.
Itchy vs. Non-itchy Rash
A presence of itch may help in a diagnosis of a rash. For example, bumps in keratosis pilaris usually do not itch, in acne occasionally, in folliculitis often, and in allergy (bumpy hives) regularly. Severity of itch sometimes reflects severity of the disorder, for example, mild psoriasis does not itch, but severe one does.
Here is a list of non-itchy rashes.
INFANTS and Itchy Rash
- Greasy yellowish scales on the scalp (cradle cap) are result of the overactive oil glands on the infant scalp.
- A red patchy rash under diapers (diaper rash, napkin dermatitis) is caused by fungal or bacterial infection, urine or feces irritation, atopic dermatistis or psoriasis.
- Extensive skin scaling due to a toxin released from bacterium Staphylococcus aureus occurs inStaphylococcal scalded skin syndrome (SSSS).
CHILDHOOD Diseases with Red Itchy SPOTS (Exanthema)
Exanthem (in Greek it means eruption) is widespread spotty rash, accompanied by fever, headache and malaise. It may be a result of a skin damage by viruses or bacteria, their toxins or immune reactions.
- Chickenpox (Varicella zostervirus) appears with raised red spots (papules), vesicles or pustules that crust over and fall off with time. The rash is mainly on the face and trunk.
- Measles or morbilli (rubeolla virus) appear as red spots in the level of the skin (macules – up to 1 cm) on the face, trunk, limbs, and raised whitish spots in mouth (Koplik’s spots). Cough is usually present.
- German measles (rubella virus) appear as pale red spots on the face and spreads all over the body.
- Roseola infantum or erythema subitum (herpes virus 6) appear as mild spotty rash on the face and trunk.
- Fifth disease or erythema infectiosum (Parvovirus B19) is characterized by ‘slapped cheeks’ rash, followed by spotty rash on trunk and limbs.
- Hand, foot and mouth disease (Coxsackie virus A16, or Enterovirus 71): small blisters appear on the hands and feet, and painful ulcers appear in the mouth.
- Pictures of chickenpox, measles, German measles, scarlet fever, fifth disease, and hand, foot and mouth disease.
- Hepatitis B, Epstein Barr virus (infectious mononucleosis), coxsackie viruses, echo viruses, and respiratory syncytial virus may appear as Gianotti Crosti syndrome with prominent red spots on limbs, trunk and finally on the face. In Asymmetric Periflexural Exanthem of Childhood (APEC), a rash, supposedly of a viral origin, appears in armpits or groin and spreads mainly over one side of the body. Pictures.
- Scarlet fever or scarlatina (Streptococcus group A or, rarely, Staphylococcus aureus) appear as tinny scarlet blotches (boiled lobster appearance) that coalesce and may cover the whole body in 24 hours. Sore throat and fever are usually present.
- Meningococcal disease is infection of the inner brain membrane (meninge) by a bacterium Neisseria memingitidis. A red dotty rash represents small bleedings that do not disappear after applying pressure. Dots may merge to form a bruise like rash. Neck stiffness, headache, nausea, fever and sensitivity to light are main symptoms.
- Kawasaki disease is inflammatory disease of uncertain (probably infectious) cause, resulting in red eyes, lips, tongue, hands and feet, widespread rash on the trunk, fever, malaise, and heart abnormalities.
CHILDHOOD Diseases With Red Scaly PATCHES
- Rash around the mouth in small children may be due to irritation from alkaline saliva.
- Rounded areas of hair loss and scaly skin appear in scalp ringworm (fungal infection caused by Tinea capitis).
Itchy Rashes in PREGNANCY
- PUPPP (Pruritic Urticarial Papules and Plaques of Pregnancy), also known as Polymorphous Eruption of Pregnancy or Polymorphic eruption, is an itchy bumpy reddish rash appearing in the stretch marks of the abdomen in the last 3 months of pregnancy, and clears with delivery.
Itchy Red BUMPS
- Insect bites. Red, itchy, and often painful bump(s) appear on the site of a bite by flies, mosquitoes, ants, bees, wasps, spiders, scorpions, or snakes.
- A foreign object in the skin, like a thorn, causes a bumpy red inflammation.
- Acne vulgaris – common acne (itch only occasionally) appear mostly in adolescence as red bumps with occasional white centers (whiteheads), and regularly with tinny black caps that block the hair follicles (blackheads)
- Acne rosacea
- Razor bumps appear as red bumps several hours after shaving or depilation; they are caused by ingrown hair
- Nonspecific skin rashes may be side effect of various drugs.
- A stye is a barley-sized red itchy bump caused by a bacterial infection of the hair follicle on the eyelid. A hordeolum is a pea-sized itchy red bump on the eyelid due to a non-infectious inflammation of the eyelid soft tissues. Itchy eyelids in detail.
- Miliaria (sweet rash) is a bumpy red rash, resulting from obstruction of the sweat glands, appearing in hot weather, mostly on skin areas covered by clothes.
- Milia are small (1-2 mm) cysts on the face formed from blocked hair follicles or sweat glands.
- Staphylococcal folliculitis appears as red bumps with white centers, just like acne, usually from staph infection of the hair follicles.
- Hot tub folliculitis appears with bumps with red haloes up to 1 cm in size, appearing under a swim-suit, after using hot tubs contaminated by a bacterium Pseudomonas aeruginosa.
- Eosinophilic folliculitisappears as pale red bumps on the face and neck, mostly in persons with immune deficiency (like in AIDS)
- Sea bather’s eruption are itchy red bumps appearing under a swimming suit due to a reaction on jellyfish larvae.
- Perioral dermatitis appears as a scaly rash around the mouth and eyes, almost exclusively in women
- Grover’s disease mostly appears in men over 50 who are unwell. Small pimple-like red bumps appear on the chest or back.
- Bumpy hives are small pin-sized bumps with pinkish or reddish haloes around them. They are usually caused by an allergic reaction to physical stimuli like heat, cold, pressure, stress (cholinergic urticaria) or in allergy to food, medicines, cosmetics, sunscreens, hair dyes, jewelry, plants (poison ivy, poison oak) or sweat (prickly heat).
- Disseminate and recurrent infundibulofolliculitis (DRIF)
- Filariasis , strongyloidiasis
- Rocky mountain spotted fever is caused by rickettsiae, appears mainly in North America, and is characterized by groups of red blotches anywhere on the body. High fever is usually present.
- Dengue fever is a flu-like viral illness, transmitted by mosquitoes from human to human. It appears with measles-like rash, high fever and muscular pains.
Itchy BOILS, NODULES and LUMPS
- Afuruncle is a prominent, red, often painful bump (may be over 1 cm in size), usually appearing on the back of the neck or limbs, as a result of a staph infection. Carbuncle is a collection of furuncles that have merged together.
- In nodular prurigo several itchy red nodules with a warty surface appear mainly on the limbs. The cause is not known.
- Erythema nodosum appears as rounded slightly elevated red patches several cm in size, mainly on the lower legs (also on the thighs or forearms). They represent inflammation of under-skin fat and may occur in tuberculosis, sarcoidosis, as side effect of drugs (sulphonamides, salycilates), contraceptive pills, or in pregnancy.
- In hidradenitis suppurativa, itchy lumps that may ooze fluid appear in the armpits or in the groin area.
Itchy Nevuses – Birthmarks
Nevus is a chronic delimited rash appearing as macule or mole.
Itchy Red PATCHES Without Scaling or Blisters
- Mild sunburn appears as an itchy burning patch on the skin several hours after sun exposure.
- Hives (urticaria) , acute or chronic, physical urticaria (solar urticaria)
- Extensive red discoloration of the face, neck and upper chest appears within 30 minutes after scombroid fish poisoning.
- Pityriasis rosea (herpes virus 6 and 7). Pale red patch (‘Herald patch’) few cm in size is followed by other small red scaly patches, mainly on trunk.
- Granuloma annulare mostly appear in children or young adults as a red ring with the unaffected center. The cause is not known.
- Dermatomyositis is a muscular disease with a scaly reddish/violaceus rash, mainly on arms.
Itchy SCALING Patches
- Fungal infections appear as scaly areas, mostly on the feet (athlete’s foot – Tinea pedis), in the groin (jock itch – Tinea cruris), on the body (ringworm of the body – Tinea corporis), or on the scalp (ringworm of the scalp – Tinea capitis). Details about itchy legs.
- Lichen sclerosus is an itchy, shiny, scaly rash, mostly appearing on the women genitalia, but occasionally also on other parts of the skin, also in children or men.
- Psoriasis is a genetic disorder, appearing as thick silvery scales on a red skin surface with distinct borders, mainly on the knees and elbows, or other parts of the body, including the genital area or scalp. Itch appears only in severe cases.
Itchy Red PATCHES WITH SCALING, BLISTERS, and/or CRUSTS
- Severe sunburn Sunburn itch – prevention and treatment
- Actinic prurigo
- Chronic actinic dermatitis
- Photosensitivity is a condition in which certain drugs or ointments react with UV rays from the sun, and cause a strong skin reaction resembling a severe sunburn.
- Dry skin (xerosis)
- A cold sore (Herpes simplexvirus) appears as a group of tinny translucent blisters on a reddened skin, usually on the lip border, or near the nose. The same rash may appear on the genital mucosa.
- Shingles represent reactivation of a Herpes zoster (varicella) virus that remained dormant in the roots of the spinal or cranial nerves. It may appear several years after having chickenpox as a red rash resembling chickenpox, and extends as a stripe over the course of the cranial nerve (on the face) or spinal nerve (on the trunk or limbs), from the spine to the mid-line in the front, usually only on one side of the body.
- Poison ivy
- Severe cellulitis is an under-skin infection, appearing as a bright red patch with large blisters, mainly on the limbs, caused by a bacterium Staphylococcus aureus or group A Streptococci.
- Tinea versicolor is also known as Pityriasis versicolor.
- A dermatophytide is an allergic rash caused by an inflammatory fungal infection at a distant site.
- An id reaction is an itchy rash with blisters that often occurs on the sides of the fingers, but it can also be found on the chest or arms. It is actually caused by a fungal infection somewhere else in the body.
- Contact with certain plants, like a nettle, usually results in a burning red patch with small translucent blisters. Contact with chrysanthenum may result in a red patchy rash.
- Contact with certain sea animals, like jellyfish, may also result in a red patch.
- An eczema is a reddish patch with occasional scaling or blisters as a result of allergic contact dermatitis. It most often appears on the hands.
- Atopic dermatitis
- Erythema multiforme appears on the forearms and hands (also on the knees or feet) as a target-like rounded reddish rash with occasional blisters or crusts in the center. It occurs in certain infections or as side effect of medications.
- Impetigo appears as a red, scaly rash, often on the face in children, but also in adults and on the other parts of the body. The cause is infection with a bacterium Staphylococcus aureus.
- A discoid eczema (nummular dermatitis) appears as a coin-sized red rash anywhere on the skin.
- Paronychia is a red painful swelling of a nail base due to an infection, usually by Staphylococcus aureus.
- In pemphigus, red patches with blisters and ulcers occupy extensive areas of the skin and mouth mucosa. The cause is not known. Benign mucosal pemphigoid appears with itchy blisters.
- Pompholyx are rough translucent blisters on the hands or feet, often appearing in excessive palmar sweating.
- Scabies appears as red bumps, blisters and later scaling, mostly between fingers and toes, on inner sides of the wrists, in the skin folds, or anywhere on the body.
- Ared rash with under-skin canals appears in parasitic infestations with cutaneus larva migrans, tungiasis See pictures and check other causes of itchy feet and toes, like acroangiodermatitis, sweaty sock syndrome, pitted keratolysis.
- Dermatitis herpetiformis
- Palmoplantar keratoderma is yellowish thickening of the skin on the palms and/or soles, appearing in small children
- Paget disease appears as a scally itchy discoloration of the breast areola and is almost always connected with a breast cancer.
Itchy Rash With ULCERS
- Gravitational eczema (venous eczema, stasis eczema) appears on the lower legs in persons with a venous disease (varices, vasculitis) or thrombosis.
- Skin cancers: a basal or squamous cell carcinoma and, rarely, a melanoma may appear as an ulcer or ulcerated mass on the skin.
Itchy Rash on SCALP, BEARD, ARMPITS or GROIN
- Dandruff appears as whitish skin flakes falling from the scalp or other hairy skin areas.
- Seborrheic dermatitis appears as yellowish, greasy, flaky skin on the scalp, around the ears or nose or in the genital area.
- Head lice and pubic lice cause red bumps with intense itching on the scalp (also on the forehead, neck or shoulders) or in the groin.
- Epidermal or sebaceous cyst
- Tinea capitis (scalp ringworm) is a fungal infection of the scalp, mostly in children.
- Barber’s itch (ringworm of the beard)
- Causes of itchy scalp in detail
- Tinea cruris (jock itch) is a fungal infection of the inner thighs and groin
- Genital warts, plaques and rashes caused by sexualy transmitted diseases (STDs) may cause itchy groin. Read about rectal and anal itch.
- In hydradenitis suppurativa, itchy lumps that may ooze fluid appear in the armpits or in the groin.
- Fox-Fordyce disease is a rare disease resembling hidradenitis suppurariva, occuring mainly in young women (13-35 years of age). Sweat glands become clogged and small itchy bumps appear under the arm, or/and in the groin.
- Causes of itchy armpits in detail
Rash Around NAILS
- Fungal infection of the nails – onychomycosis
Internal Diseases and Itchy Rash
- Liver disease with cholestasis, Wilson’s disease, brucellosis of the liver, leptospirosis, trichinosis
- Kidney disease with uremia
- Crohn’s disease
- Celiac disease
- Systemic connective tissue diseases: rheumatoid arhritis, Sjögren’s syndrome, systemic sclerosis
- Acanthosis nigricans is dry bumpy discolored skin (and mouth) lesions that often appear in abdominal malignancies.
- Lymphomatoid granulomatosis
- Androgen-, estrogen-, or drug-induced jaundice
- Hypersensitivity vasculitis, polyarteritis nodosa, polymyalgia rheumatica, Henoch- Schönlein purpura
- SLE (rarely itches)
- List of Causes of Itchy Skin