How do I know if my baby's rash is roseola?

What he had was roseola—or human herpesvirus (HHV) 6—a viral infection that typically hits kids aged six months to two years old, but bigger kids and adults can get it too. It spreads through direct contact with saliva or through droplets from a cough or sneeze, so it can be easily passed from one person to another.

As with Rowan, it usually starts with a fever that lasts three to five days. While most children aren’t very sick during the fever stage, temperatures can rise above 39.4C (103F)and, in some rare cases, kids can suffer from related seizures or convulsions.

When the fever ends, a rash takes over, with pinkish red spots on the torso, arms, legs and face. The rash can last anywhere from a few hours to two days and, though it may not look pleasant, is usually not itchy or painful.

With its long duration and physical symptoms, roseola is just the kind of thing that can make a parent who isn’t familiar with the condition a bit frantic.“I was a little concerned because I had never seen anything like that before,” says Murray.

While many parents may not have heard of the infection, roseola is very common, says Michelle Ponti, a paediatrician based in London, Ontario. “Typically, by age three, about 75 percent of children have been exposed, so it’s extremely common,” she says. “That’s not to say that everybody gets the high fever and rash, but it’s typical.”

While the fever and roseola rash can be alarming for parents, most children recover with no treatment. However, parents should be vigilant during the early stages of the infection and make sure that children drink plenty of fluids and get lots of rest, says Ponti. According to the Canadian Paediatric Society, you should take your child to a doctor if the fever exceeds 72 hours, or three days.

“I think the concern would be if a child has a high fever that isn’t getting better after several days,” she says. “Usually, in very young infants who are less than six months old, we would be more concerned about a high fever and they would definitely need to be seen by a physician.”

Children who have developed roseola should follow the typical precautions of someone who is sick—washing their hands frequently, covering their coughs and sneezes—though that can obviously be a challenge when dealing with an infant.

On Murray’s second time through roseola—this time with Ryder, when he was also 18 months old—she recognized the signs and played it cool.

“I didn’t even bother taking him to the doctor because I knew what it was and what to expect,” she says. “About four or five days after the rash appeared, it was totally gone.”

A high fever is often the first sign of roseola in children. A fever stemming from this illness tends to spike several days before the roseola rash appears, and temperatures in small children can be as high as 105 degrees. Expect that your child will maintain a high fever for three to seven days.

Children are extremely contagious during this period, so cancel any playdates and keep their siblings at a distance if at all possible.

Cold-like symptoms are another early indication of a roseola infection and usually develop in conjunction with a high fever (103-105 degrees). Examples of cold-like symptoms associated with a roseola infection include a sore throat, runny nose, or cough.

In most cases, these symptoms are mild and can be managed with over-the-counter pain medications.

Children experience a loss of appetite for a myriad of reasons, but it could be a sign of a roseola infection. This is another symptom that often tags along with the fever and cold-like symptoms.

It can be scary to watch your child refusing to eat, but it's actually a protective immune response, and their appetite should return to normal within a few days. Hydration is key during a case of roseola, so encourage your child to take in plenty of water, juice, or fruit.

The eyelids can become swollen and puffy during roseola, giving your sick baby a "sleepy" look even when they are not tired. Swollen lymph nodes in the neck can also point to a roseola infection. Lymph nodes swell in response to an infection, and nodes that are 0.5 to 1 inch in diameter indicate a healthy immune response to a roseola infection.

The rash is the best-known sign of roseola, of course. This skin change starts out as small pink spots that merge into larger patches as the infection progresses. Your baby's skin may feel either bumpy or smooth to the touch, and the spots usually start on the stomach before spreading to the limbs.

The rash may appear lighter than its usual pink when you press against the skin or have a pale "halo" around its border. It shouldn't be itchy or painful and usually resolves within three to four days.

Roseola and measles are easy to differentiate. The rash associated with measles starts on the face and spreads downwards, while roseola rashes appear on the stomach and spread out toward the limbs.

The measles rash is typically darker red, bumpier, and more pervasive than roseola. Additionally, roseola rashes don't appear until the child's fever has broken; measles rashes appear while fever and general sickness are still taking their toll.

The rash resulting from chicken pox is very different, as well. A chickenpox rash is made up of small fluid-filled blisters that cover the entire body. These blisters often burst and scab over, becoming extremely itchy. Rashes resulting from roseola are rarely itchy and never result in blisters or scabs.

While a roseola rash first appears on the stomach, a chickenpox rash originates on the chest, back, or face.

Read more: An age-by-age guide to children's skin rashes and conditions 
Your ultimate guide to the most common kid illnesses