Rash

Rash

Severe rash on a white male

A rash is a change of the skin which affects its color, appearance, or texture. A rash may be localized in one part of the body, or affect all the skin. Rashes may cause the skin to change color, itch, become warm, bumpy, dry, cracked or blistered, swell and may be painful. The causes, and therefore treatments for rashes, vary widely. Diagnosis must take into account such things as the appearance of the rash, other symptoms, what the patient may have been exposed to, occupation, and occurrence in family members. The diagnosis may confirm any number of conditions.

The presence of a rash may aid associated signs and symptoms are diagnostic of certain diseases. For example, the rash in measles is an erythematous, maculopapular rash that begins a few days after the fever starts. It classically starts at the head and spreads downwards.

Causes

Common causes of rashes include:

• Anxiety
• Allergies, for example to foods, dyes, medicines, insect stings, metals such as zinc or nickel; such rashes are often called hives.
• Skin contact with an irritant
• Bacterial or viral infection, e.g., by the viruses that cause chickenpox, smallpox, cold sores and measles
• Fungal infection, such as ringworm
• Reaction to vaccination
• Skin diseases such as eczema or 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

Uncommon causes:

• Autoimmune disorders such as psoriasis
• Lead poisoning
• Pregnancy

Evaluation

The causes of a rash are extremely broad, which may make the evaluation of a rash extremely difficult. An accurate evaluation by a doctor may only be made in the context of a thorough history (What medication is the patient taking? What is the patient's occupation? Where has the patient been?) and complete physical examination.

Points to note in the examination include:

• The appearance: e.g., purpuric (typical of vasculitis and Meningococcal septicemia), fine and like sandpaper (typical of scarlet fever); umbilicated lesions are typical of molluscum contagiosum (and in the past, small pox); plaques with silver scales are typical of psoriasis.
• The distribution: e.g., the rash of scarlet fever becomes confluent and forms bright red lines in the skin creases of the neck, armpits and groins (Pastia's lines); the vesicles of chicken pox seem to follow the hollows of the body (they are more prominent along the depression of the spine on the back and in the hollows of both shoulder blades); very few rashes affect the palms of the hands and soles of the feet (secondary syphilis, rickettsia or spotted fevers, guttate psoriasis, hand, foot and mouth disease, keratoderma blenorrhagica);
• Symmetry: e.g., herpes zoster usually only affects one side of the body and does not cross the midline.

Typically, it is never a good habit for one to scratch a rash, as doing so may invigorate the rash and cause it to spread. Gently rubbing the rash may provide temporary relief, but it is more than likely better to avoid contact with the affected areas altogether.

Overview of symptoms

Skin disease	Symptoms	Usual area of body
Acne	Covered in small pus-filled sacs, blackheads, pimples or sore red bumps	Face, chest or back
Rosacea	Flushed appearance or Redness	Around 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 itchy bumps on the skin	Anywhere and can be sprinked randomly
Allergic reaction	Irregular, raised or flat red sores that appeared after taking medicine/drugs or eating certain foods	Anywhere
Hives	Bumps formed suddenly	Anywhere but usually first noticed on face
Seborrheic dermatitis	Bumps and swelling	Near glands
Cradle Cap	Dry, scaly skin	Cover the head of a child
Irritant contact dermatitis	Red, itchy, scaly or oily rash	Eyebrows, nose, edge of the scalp, point of contact with jewellery, perfume or clothing.
Allergic Contact Dermatitis caused by poison ivy, oak or sumac	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 (eg. 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, 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 don't 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
Milia	Lots of 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
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