Health Information A-Z

Health Information A-Z

Rash - Widespread and Cause Unknown


  • Rash over most of the body (widespread or generalized)
  • Occasionally just on hands, feet, and buttocks - but symmetrical
  • Small spots, large spots, or solid red
  • Cause of rash is unknown

General Information

  • Three widespread rashes that individuals may be able to recognize are: hives, insect bites, and sunburn. If present, use that topic. If not, use this topic.
  • An adult with fever and rash should seek medical attention immediately. A number of serious infections present in this manner.

Rocky Mountain Spotted Fever
Rocky Mountain Spotted Fever
  • Child's right hand and wrist displaying the characteristic spotted rash of Rocky Mountain spotted fever.
  • Rocky Mountain spotted fever is the most severe and most frequently reported rickettsial illness in the United States. The disease is caused by Rickettsia rickettsii, a species of bacteria that is spread to humans by ixodid (hard) ticks.

Toxic Shock Syndrome
Toxic Shock Syndrome
  • This bright red, sunburn-like rash is from Toxic Shock Syndrome. It usually begins after either wound infection, recent surgery, or tampon use.
  • The symptoms of Toxic shock syndrome include a sudden onset of fever, chills, vomiting, diarrhea, muscle pains and rash. Hypotension (low blood pressure) also occurs.

Penicillin Rash on the Arm
Penicillin Rash on the Arm

This patient had a widespread rash from an allergy to penicillin. The picture shows the arm.

Scarlet Fever Rash in a Person with Strep Throat
Scarlet Fever Rash in a Person with Strep Throat

Scarlet fever is a disease caused by the same bacteria (streptococcus) that causes strep throat. A person with Scarlet fever has a throat that is red and sore, usually a fever, usually swollen glands in the neck, and a Scarlet fever rash.

  • The photo shows the typical Scarlet Fever rash on the forearm.
  • The scarlet fever rash first appears as tiny red bumps on the chest and abdomen that may spread all over the body. Looking like a sunburn, it feels like a rough piece of sandpaper, and lasts about 2-5 days.

Face of Boy with Measles
Face of Boy with Measles
  • Third day of rash.
  • Measles is an acute, highly contagious viral disease. Symptoms include fever, conjunctivitis (red eyes), runny nose, cough, and spots on the inside cheeks (inside of mouth).
  • A red blotchy rash appears around day 3 of the illness, first on the face, and then becoming generalized.

See More Appropriate Topic (instead of this one) If

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Call 911 Now (you may need an ambulance) If

  • Very weak (can't stand)
  • Purple or blood-colored rash with fever
  • Sudden onset of rash (within past 2 hours) and also have difficulty with breathing or swallowing
  • Difficult to awaken or acting confused
  • Life-threatening reaction (anaphylaxis) in the past to similar substance (e.g., food, insect bite/sting, chemical, etc.) and less than 2 hours since exposure

Call Your Doctor Now (night or day) If

  • You feel weak or very sick
  • Purple or blood-colored rash without fever
  • Bright red skin that peels off in sheets
  • Bright red, sunburn-like rash after either wound infection or recent surgery
  • Bright red, sunburn-like rash after either tampon use or nasal packing
  • Rash looks like large or small blisters (i.e. fluid-filled bubbles or sacs on the skin)
  • Rash began within 4 hours of a new prescription medication
  • Fever
  • Headache
  • Stiff neck (unable to touch chin to chest)
  • Joint pain or swelling
  • Sores also present in mouth

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

  • A widespread rash, but none of the symptoms described above
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  1. Reassurance: There are many causes of widespread rashes and most of the time they are not serious. Common causes include viral illness (e.g., cold viruses) and allergic reactions (to a food, medicine, or environmental exposure).
  2. For Non-Itchy Rashes: No treatment is necessary, except for heat rashes, which respond to cool baths.
  3. For Itchy Rashes:
    • Wash the skin once with gentle non-perfumed soap to remove any irritants. Rince the soap off thoroughly.
    • You may also take an oatmeal (Aveeno) bath or take an anithistamine medication by mouth to help reduce the itching.
  4. Oatmeal Aveeno Bath for Itching: Sprinkle contents of one Aveeno packet under running faucet with comfortably warm water. Bathe for 15 - 20 minutes, 1-2 times daily. Pat dry with a towel - do not rub.
  5. Oral Antihistamine Medication for Itching: Take an antihistamine like diphenhydramine (Benadryl) for widespread rashes that itch. The adult dosage of Benadryl is 25-50 mg by mouth 4 times daily.
    • Do not take antihistamine medications if you have prostate enlargement.
    • Antihistamines may cause sleepiness. Do not drink, drive or operate dangerous machinery while taking antihistamines.
    • An over-the-counter antihistamine that causes less sleepiness is loratadine (e.g., Alavert or Claritin).
    • Read the package instructions thoroughly on all medications that you take
  6. Contagiousness: Avoid contact with pregnant women until a diagnosis is made. Most viral rashes are contagious (especially if a fever is present). You can return to work or school after the rash is gone or when your doctor says it is safe to return with the rash.
  7. Expected Course: Most viral rashes disappear within 48 hours.
  8. Call Your Doctor If:
    • You become worse

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

Disclaimer: This information is not intended be a substitute for professional medical advice. It is provided for educational purposes only. You assume full responsibility for how you choose to use this information.

Last Reviewed: 3/15/2008

Last Revised: 3/31/2008

Developed by SelfCareNet, Inc.

SelfCareNet, Inc. Copyright (C) 2000-2008 David Thompson, M.D. FACEP All Rights Reserved.

This content is reviewed periodically and is subject to change as new healthcare information becomes available. The information is intended to inform and educate and is not a replacement for medical evaluation, advice, diagnosis or treatment by a healthcare professional.

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