How Can You Tell if a Rash Is Serious?

Reviewed on 6/24/2020

What is a skin rash?

Shingles (Herpes Zoster)
Shingles, also known as herpes zoster, is a skin disease caused by the return of a chickenpox infection from latently infected nerve cells in the spinal cord or brain.

An itchy area of skin that’s caused by infection, allergy, or injury is known as a rash. Usually, a rash on the skin looks red and is accompanied by irritation. It may or may not be associated with pain and swelling. Rashes usually indicate an underlying medical problem in the body.

How can you tell if a rash is serious?

A rash can become serious if immediate medical assistance is not provided when a patient has the below symptoms:

What are the most common skin rashes caused by an infection?

Bacterial, fungal, and viral infections typically present with a skin rash as a symptom. Below are a few common skin rashes caused by infection:

Herpes zoster infection or shingles

Herpes simplex infection (HSV): 

  • It is caused by a DNA virus called herpes simplex virus. 
  • It is a sexually transmitted disease
  • Transmission occurs due to the body fluids of an infected person contacting the open skin of another person.
  • Symptoms include abnormal redness on skin (like a sunburn) with tiny multiple sacs of fluids (vesicles) on the mouth, genitals, anal region, and buttocks. 
  • There is no cure for this infection; however, infection is self-resolving. Usually, antiviral drugs are recommended by doctors to shorten the course of this disease.

Tinea corporis (ringworm):


  • It is caused by the varicella-zoster virus.
  • This infection is highly contagious via air droplets from a contagious person and direct contact with the virus particles.
  • Usually affects children younger than 10 years old, the infection starts after 10 to 21 days of contact. 
  • Symptoms include skin rash with severe and many pus-filled sacs on the body with a low-grade fever.
  • This infection usually resolves within five to 10 days. Treatment options include only supportive therapy (keep the patient clean and healthy). Initially, it starts on the face and then develops on other sites of the body.
  • If it affects individuals with a compromised immune system, doctors usually prescribe antiviral drugs. 

Hand, foot, and mouth disease (HFMD):

  • It is caused by a highly contagious virus called coxsackievirus A16.
  • Symptoms include abnormal redness on the skin (looks like sunburn) with 2-3 mm multiple sacs of fluid (vesicles) on mouth, feet, and palms. Patients have a fever, sore throat, mouth ulcers, and loss of appetite.
  • It usually affects infants and children and is transmitted through nose and mouth secretions or fecal matter. 
  • Treatment includes supportive care with fever-reducing drugs and sometimes anesthesia for relieving the symptoms. Typically resolves within 7 days. 

Erythema infectiosum (also called the fifth disease):

  • It is a common childhood infection caused by human parvovirus B19.
  • Transmission occurs through air droplets, blood, or blood transfusion.
  • Symptoms include fever, running nose, and headache. It has three stages:
    • Stage 1: Bright abnormal redness seen on cheeks giving slapped cheek appearance.
    • Stage 2: Abnormal bright redness with vesicles extends to hands and legs.
    • Stage 3: Abnormal redness fades away, leaving a lace-like pattern on infected areas.
  • Infection resolves within seven days without treatment in children.

Pityriasis Rosea:

  • Symptoms include a large, scaly, pink area of skin, followed by additional skin spots that are itchy and red with swelling. It usually affects the back, neck, chest, abdomen, upper arms, and legs, but the rash may differ from person to person. 
  • Treatment may not be necessary, as it heals within 12 weeks with sun exposure or ultraviolet light.



Ringworm is caused by a fungus. See Answer

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REFERENCES: Rashes You Need to Know: Common Dermatologic Diagnoses: (

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