Merck Manual

Please confirm that you are not located inside the Russian Federation

honeypot link

Overview of Viral Infections in Children


Brenda L. Tesini

, MD, University of Rochester School of Medicine and Dentistry

Last full review/revision Sep 2019| Content last modified Sep 2019
Click here for the Professional Version
Topic Resources

A virus is a small infectious organism—much smaller than a fungus or bacterium—that must invade a living cell to reproduce (see Overview of Viral Infections).

Viral infections are common among people of all ages but often seem to be concentrated in infants and children. Most childhood viral infections are not serious and include such diverse illnesses as colds, sore throat, vomiting and diarrhea, and fever with a rash. Some viral illnesses that cause more serious disease, such as measles, are less common now due to widespread immunization. Several types of viral infections that children can acquire are discussed in adult viral infections.

Generally, parents can tell whether their child is ill with a potentially serious infection and needs immediate medical care. This is particularly true for children beyond infancy. Many viral infections are so distinctive that a doctor can diagnose them based on their symptoms. A doctor usually does not need to have a laboratory identify the specific virus involved.

Most children with viral infections get better without treatment. Many viral infections result in fever and body aches or discomfort. Doctors sometimes treat these symptoms with acetaminophen or ibuprofen. Aspirin is not given to children or adolescents with these symptoms because it increases the risk of Reye syndrome in those who have certain viral infections. Antibiotics cannot cure viral infections. However, there are antiviral drugs available for a few viral infections such as hepatitis, some herpesviruses, influenza, and human immunodeficiency virus (HIV).


Some Viral Infections in Children That Cause a Rash


Period of Incubation

Period of Contagiousness

Site of Rash

Nature of Rash

Measles (rubeola)

7 to 14 days

From 2 to 4 days before the rash appears until 2 to 5 days after

Starts around the ears and on the face and neck

Spreads to the trunk, arms, and legs

Begins 3 to 5 days after the start of fever, runny nose, cough, red eyes, and sore throat and lasts 3 to 5 days

Irregular, flat, red areas that soon become raised

Rubella (German measles)

14 to 21 days

From a week before the rash appears until a week after it appears

Infected newborns are usually contagious for many months

Starts on the face and neck

Spreads to the trunk, arms, and legs

Begins 1 or 2 days after the start of mild fever, swollen and tender lymph nodes, red eyes, and headache and lasts 3 to 5 days

Fine, pinkish, flat rash

Roseola infantum (exanthem subitum or pseudorubella)

About 5 to 15 days


Starts on the trunk and usually spreads to the neck, face, arms, and legs

Begins on about the 4th day after the start of a high fever and usually just when the fever ends and lasts for hours to a few days

Pinkish red, flat or raised rash

Erythema infectiosum (fifth disease or parvovirus B19 infection)

4 to 14 days

From before the start of the rash until 1 to 2 days after

Starts on the cheeks

Spreads to the arms, legs, and trunk

Begins several days after the start of low fever, headache, and runny nose and lasts 5 to 10 days

May recur for several weeks

Red rash on the cheeks (slapped-cheek rash) spreads to the arms, legs, and trunk and becomes lighter and blotchy with lacy patterns

Chickenpox (varicella)

11 to 15 days

From a few days before the start of symptoms until all spots have crusted

Starts on the face, neck, and trunk

Spreads to the arms, legs, and scalp

Appears in crops, so various stages are present simultaneously

Begins shortly after the start of fever and feeling of illness and lasts a few days to 2 weeks

Small, flat, red spots that become raised and form round, fluid-filled blisters against a red background before finally crusting

Drugs Mentioned In This Article

Generic Name Select Brand Names
No US brand name
NOTE: This is the Consumer Version. DOCTORS: Click here for the Professional Version
Click here for the Professional Version
Others also read

Also of Interest

Download the Manuals App iOS ANDROID
Download the Manuals App iOS ANDROID
Download the Manuals App iOS ANDROID