Roseola, rarely known as “sixth disease,” is a contagious illness that’s caused by a virus. It shows up as a fever followed by a signature skin rash.

The infection is usually not serious and typically affects children between the ages of 6 months and 2 years.

Roseola is so common that most kids have had it by the time they reach kindergarten.

Read on to learn more about how to identify and treat roseola.

The most common symptoms of roseola are a sudden, high fever followed by a skin rash. A fever is considered high if your child’s temperature is between 102 and 105°F (38.8-40.5°C).

The fever typically lasts 3-7 days. The rash develops after the fever goes away, usually within 12 to 24 hours.

The skin rash is pink and may be flat or raised. It usually starts on the abdomen and then spreads to the face, arms, and legs. This hallmark rash is a sign that the virus is at the end of its course.

Other symptoms of roseola may include:

  • irritability
  • eyelid swelling
  • ear pain
  • decreased appetite
  • swollen glands
  • mild diarrhea
  • sore throat or mild cough
  • febrile seizures, which are convulsions due to a high fever

Once your child is exposed to the virus, it could take between 5 and 15 days before symptoms develop.

Some kids have the virus but don’t experience any noticeable symptoms.

Some people confuse the roseola skin rash with the measles skin rash. However, these rashes are distinctly different.

The measles rash is red or reddish-brown. It usually starts on the face and works its way down, ultimately covering the entire body with blotches of bumps.

The roseola rash is pink or “rosy” in color and typically starts on the abdomen before spreading to the face, arms, and legs.

Children with roseola typically feel better once the rash appears. However, a child with measles may still feel ill while they have a rash.

Roseola is most often caused by exposure to the human herpes virus (HHV) type 6.

The illness can also be caused by another herpes virus, known as human herpes 7.

Like other viruses, roseola is spread through small droplets of fluid, usually when someone coughs, talks, or sneezes.

The incubation period for roseola is about 14 days. This means a child with roseola who hasn’t yet developed symptoms can easily spread the infection to another child.

Roseola outbreaks can occur at any time of the year.

Although it’s rare, adults can contract roseola if they never had the virus as a child.

The illness is typically milder in adults, but they can pass the infection on to children.

Call your child’s doctor if they:

  • have a fever higher than 103°F (39.4°C)
  • have a rash that hasn’t improved after three days
  • have a fever that lasts longer than seven days
  • have symptoms that worsen or don’t improve
  • stop drinking fluids
  • seem unusually sleepy or otherwise very ill

Also, be sure to contact a medical professional right away if your child experiences a febrile seizure or has any other serious illnesses, especially a condition that affects the immune system.

Roseola can sometimes be difficult to diagnose because its symptoms mimic those of other common illnesses in kids. Also, because the fever comes and then resolves before the rash appears, roseola is usually diagnosed only after the fever is gone and your child is feeling better.

Read more: When to be concerned by rash after fever in toddlers »

Doctors typically confirm that a child has roseola by examining the signature rash. A blood test may also be performed to check for antibodies to roseola, though this is rarely necessary.

Roseola will typically go away on its own. There’s no specific treatment for the illness.

Doctors don’t prescribe antibiotic drugs for roseola because it’s caused by a virus. Antibiotics only work to treat illnesses caused by bacteria.

Your doctor might tell you to give your child over-the-counter medicines, such as acetaminophen (Tylenol) or ibuprofen (Advil, Motrin) to help lower fever and reduce pain.

Don’t give aspirin to a child under 18 years old. Use of this medicine has been linked to Reye's syndrome, which is a rare, but sometimes life-threatening, condition. Children and teens recovering from chickenpox or the flu, in particular, shouldn’t take aspirin.

It’s important to give kids with roseola extra fluids, so they don’t get dehydrated.

In certain children or adults with a weakened immune system, physicians might prescribe the antiviral drug ganciclovir (Cytovene) to treat roseola.

You can help keep your child comfortable by dressing them in cool clothing, giving them a sponge bath, or offering them cool treats such as popsicles.

Learn more: How to treat your baby’s fever »

Your child can return to normal activities when they are free of a fever for at least 24 hours, and when other symptoms have gone away.

Roseola is contagious during the fever phase, but not when a child has a rash only.

If someone in the family has roseola, it’s important to wash hands frequently to prevent spreading the illness.

You can help your child recover by making sure they get enough rest and stay hydrated.

Most kids will recover within a week of the first signs of fever.

Kids with roseola typically have a good outlook and will recover without any treatment.

Roseola can cause febrile seizures in some children. In very rare cases, the illness can lead to serious complications, such as:

Most kids develop antibodies to roseola by the time they reach school age, which makes them immune to a repeat infection.