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Rash - Localized and Cause Unknown

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Impetigo of Elbow

Erythema Migrans Rash

Ringworm Rash on Arm

Ringworm Rash on Leg

Shingles on Chest

Shingles on Neck


  • Rash or redness on one part of the body (localized or clustered)

  • Cause of rash is unknown


  • Localized areas of redness or skin irritation

  • Rash may be smooth (macular) or slightly bumpy (papular)

  • Rash may look like small spots, large spots or solid red

General Information

  • Three localized rashes that individuals may be able to recognize are: Athlete's Foot, insect bites, and poison ivy. If present, use that topic. If not, use this topic.

  • The main cause of a new localized rash is often skin contact with some irritant.

  • The main cause of a persistent localized rash is often contact dermatitis, which is an allergic reaction to skin contact with some substance.

  • Cellulitis is the medical term for an infection of the skin. There is spreading redness. The skin is also painful, tender to touch, and warm. There may or may not be any drainage or discharge. Antibiotic treatment is required.

Contact Dermatitis

Contact dermatitis is a common cause of persistent localized rashes. Contact dermatitis usually presents as localized raised red spots. Occasionally it progresses to localized blisters (e.g., poison ivy. Contact dermatitis only occurs after repeated contacts with the allergic substance. Once sensitized to a substance, however, reactions occur 12 to 24 hours after exposure. The location of the rash may suggest the cause.

  • Poison ivy or oak: exposed areas (e.g., hands, forearms)

  • Nickel (metal): neck from necklaces, earlobe from earrings, belly button from metal snaps inside pants, wrist from wrist watch.

  • Tanning agents in leather: tops of the feet from shoes or hands after wearing leather gloves

  • Preservatives in creams, lotions, sunscreens, shampoos: site of application

  • Neomycin in antibiotic ointment: site of application


  • Symptoms: Erythematous and macerated (moist) areas between skin folds. Sometimes the patient may experience mild burning discomfort or itching.

  • Location: The most common area is under the breasts. However, in obese individuals it can happen in multiple other areas of the body wherever skin folds over and creates a moist pocket. In obese individuals another common area is where the abdomen overlaps onto the upper thigh.

  • Risk factors: Obesity, heat, humidity, sweating, occlusive clothing, and diabetes.

  • Complications: May become infected with yeast; a secondary bacterial infection of the skin can sometimes occur.

  • Treatment: Reducing the moisture in the area is the most important thing to do. Strategies for accomplishing this include wearing loose clothing, drying area with warm hair dryer or fan, keeping skin folds open to the air with a towel, and losing weight. Sometimes anti-fungal cream is helpful.

If not, see these topics

  • The rash is from INSECT BITES

  • You have a WOUND INFECTION

  • You have ATHLETE'S FOOT

  • You have JOCK ITCH

  • You have POISON IVY


When to Call Your Doctor

call now

Call Your Doctor Now (night or day) If

  • You feel weak or very sick

  • Purple or blood-colored spots or dots that are not from injury

  • Bright red area or red streak (but not sunburn)

  • Rash area is very painful

  • Multiple small blisters grouped together in one area of body

  • Fever

call within 24 hours

Call Your Doctor Within 24 Hours (between 9 am and 4 pm) If

  • You think you need to be seen

  • Severe itching is present

  • Genital area rash

  • Lyme disease suspected (e.g., bull's eye rash or tick bite in past month)

  • Tender bumps in armpits

call within 24 hours

Call Your Doctor During Weekday Office Hours If

  • You have other questions or concerns

  • Looks like a boil or infected sore or other infected rash

  • Rash lasts longer than 7 days

  • Red, moist, irritated area between skin folds (or under larger breasts)

home care

Self Care at Home If

  • Mild localized rash and you don't think you need to be seen



General Care Advice for Mild Localized Rash

  1. Avoid the Cause: Try to find the cause. Consider irritants like a plant (e.g., poison ivy or evergreens), chemicals (e.g., solvents or insecticides), fiberglass, a new cosmetic, or new jewelry (called contact dermatitis). A pet may be carrying the irritating substance (e.g., with poison ivy or poison oak).

  2. Avoid Soap: Wash the area once thoroughly with soap to remove any remaining irritants. Thereafter avoid soaps to this area. Cleanse the area when needed with warm water.

  3. Local Cold: Apply or soak in cold water for 20 minutes every 3 to 4 hours to reduce itching or pain.

  4. Hydrocortisone Cream for Itching: If the itch is more than mild, apply 1% hydrocortisone cream 4 times a day to reduce itching. Use it for 5 days.

    • Keep the cream in the refrigerator (Reason: it feels better if applied cold).

    • Available over-the-counter in U.S. as 0.5% and 1% cream.

    • Available over-the-counter in Canada as 0.5% cream.

    • CAUTION: Do not use hydrocortisone cream on suspected Athlete's Foot, Jock Itch, ringworm, or impetigo.

  5. Avoid Scratching: Try not to scratch. Cut your fingernails short.

  6. Contagiousness: Adults with localized rashes do not need to miss any work or school.

  7. Expected Course: Most of these rashes pass in 2 to 3 days.

  8. Call Your Doctor If:

    • Rash spreads or becomes worse

    • Rash lasts longer than 1 week

    • You develop any of the "Call Your Doctor" symptoms.

General Care Advice for Pimples

  1. Reassurance: A pimple is a tiny, superficial infection without any redness. Pimples can occur with acne or friction.

  2. Cleansing: Wash the infected area with warm water and an antibacterial soap 3 times a day.

  3. Antibiotic Ointment: Apply an over-the-counter antibiotic ointment to the infected area 3 times per day.

  4. Call Your Doctor If:

    • Redness occurs

    • Fever occurs

    • More pimples occur

    • You develop any of the "Call Your Doctor" symptoms.

And remember, contact your doctor if you develop any of the "Call Your Doctor" symptoms.

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