Three-day fever

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Three-day fever (exanthema subitum ) is an acute, highly contagious viral disease caused by herpes viruses. It is characterized by a sudden increase in high fever that lasts for three to four days. A rash then develops, which disappears after a few days.

Learn more about three-day fever here.

Quick Overview

  • Symptoms: Sudden fever that lasts about three (rarely five) days, after the fever has gone, fine-spotted, bright red rash all over the body, rarely swelling of the eyelids, intestinal inflammation, coughing , sometimes febrile convulsions, rarely flu-like in adults
  • Causes and risk factors: Highly contagious viral disease caused by human herpesvirus 6 or 7 (HHV-6, HHV-7), infection through saliva , droplet infection possible, rarely other transmission, healthy people often carriers
  • Diagnosis: Based on the typical symptoms, blood test for antibodies possible, possibly molecular-biological detection using PCR (polymerase chain reaction)
  • Treatment: Usually not necessary, if necessary: ​​Treatment of the symptoms, lowering the fever with a calf wrap or paracetamol , drinking a lot, consult a doctor in the event of fever cramps
  • Prognosis: Usually good, disease often disappears as quickly as it appears, complications are rare

What is three day fever?

The three-day fever (also: three-day-fever or 3-day fever), which is also called roseola infantum, three-day fever rash, exanthema subitum or “sixth disease”, is a mostly harmless viral infection with a herpes virus – more precisely with the Human Herpesvirus 6 (HHV-6) and Human Herpesvirus 7 (HHV-7).

It occurs in babies and children predominantly between the sixth and 24th month. By the time they are three years old, almost all children have come into contact with the virus. Three-day fever does not occur seasonally, children are infected with it all year round.

As the name suggests, in many cases it is accompanied by a fever lasting around three days and a skin rash .

Three-day fever in the baby

At birth, the mother’s antibodies are passively transmitted to the newborn, providing limited nest protection from three-day fever in the first few months of life. For this reason, three-day fever occurs very rarely before the third month of life.

Three-day fever in adults

This type  fever occurs rarely in adults – most have already had the disease in infancy. If so, then it manifests itself through flu-like symptoms, comparable to those of glandular fever (mononucleosis).

In adults with a weakened immune system, a so-called pneumonitis, in which the lungs become chronically inflamed, is possible.

As with any infection with herpes viruses, the viruses remain in the body for life. Doctors call this a latent infection . However, this may become active again – but only in very rare cases when the immune system is severely impaired, for example after immunosuppression due to an organ transplant or after receiving a bone marrow transplant.


After the fever has subsided, a fine, light red rash (exanthema) develops very quickly (subito) all over the body in around a quarter of those affected . The rash in three-day fever primarily affects the trunk and neck. In some cases, the spots unite and thus become larger.

Later it is possible for the rash to spread to the arms and legs. It also occurs on the mucous membranes, mainly on the soft palate.

In many cases, the three-day fever rash disappears  as suddenly as it came, i.e. in a few hours to a maximum of two days.

Other symptoms

In addition to the fever and rash, some children have other symptoms, but these usually subside once the rash has cleared:

  • Eyelid swelling
  • Reddened eardrums
  • Intestinal inflammation
  • Cough
  • Swollen cervical lymph nodes
  • Bulging fontanel (in infants)

In older children, as in adults, three-day fever often resembles glandular fever .

Febrile seizure

In about a third of the cases of infection, the three-day fever is also accompanied by a febrile seizure . The child loses consciousness and twitches both arms and legs. This looks very worrying, but the febrile seizure usually stops after a few minutes and has no consequences. Nevertheless, after such an incident, you should urgently consult the pediatrician.

In very rare cases, three-day fever can lead to complications such as meningitis, pneumonia , liver inflammation or retinitis.

Causes and risk factors

The causative agents of three-day fever are herpes viruses (human herpes virus type 6, more rarely type 7). The herpesvirus type 6 (HHV-6) has two subgroups (serotypes) A ​​and B, with only the B variant having disease significance. About ten to 30 percent of the diseases are caused by HHV-7.

The average age of onset is different for the two pathogens. While HHV-6 mainly leads to three-day fever around the ninth month of life, HHV-7 triggers the disease much later around the 26th month of life.

How contagious is three-day fever?

The herpes virus is mainly transmitted via the saliva – making the three-day fever highly contagious. The virus may be transmitted via droplet infection when sneezing, coughing or speaking. Healthy children and adults who have come into contact with the virus are also possible carriers.

In very rare cases, infection occurs through organ transplantation, blood transfusions, sexual intercourse or breast milk . If the child has become infected, the three-day fever breaks out after about five to fifteen days (sometimes up to 17 days) (incubation period).

After the symptoms have subsided, i.e. after the fever and the disappearance of the skin rash, the children are often exhausted and cranky for a few days, but are usually no longer contagious.


During the acute symptoms of the disease, it is advisable to avoid visits. Ideally, after the infection has been overcome, the child goes to a day care center first without symptoms and fit again.

Investigations and diagnosis


Whenever your child has an infection with a high fever and the cause is unclear, it is advisable to consult a doctor specializing in paediatrics in order to identify serious illnesses at an early stage. Especially if the fever lasts longer than three days, feels very ill or has a very high fever.

In order to diagnose whether you have three-day fever, the doctor will ask you about your medical history and then carry out a detailed examination. Possible questions from the doctor are:

  • When and how quickly did the fever appear?
  • How high is the fever? When was the last time you measured your fever?
  • How long have you observed the rash?
  • Does the child scratch their rash?
  • Have you observed a febrile seizure? Was the child conscious? Describe the incident in detail.

In a typical course, three-day fever can be clearly diagnosed based on the symptoms. In some cases, the doctor will examine the blood for a better diagnosis, for example in the case of an atypical course . The blood count shows increased white blood cells ( leukocytosis ) during the fever phase. As soon as the fever subsides and the rash appears, the blood count then shows low levels of white blood cells ( leukopenia ).

More precisely, the three-day fever can be diagnosed with the detection of specific IgM antibodies or HHV IgG antibodies with special tests. HHV-6 is detected in blood, urine, saliva and cerebrospinal fluid using the polymerase chain reaction (PCR).

A positive finding must always be interpreted together with the symptoms. Because traces of the virus can also be detected in people who have already had the disease.

In the case of a febrile seizure, it may be necessary to rule out meningitis , although this is rare. The doctor performs a lumbar puncture , during which he removes cerebrospinal fluid from the spinal canal (spinal cord canal).

Similar diseases

It is important to know about three-day fever and its typical course in order to distinguish it from other similar illnesses that cause fever or a rash. This applies in particular to measles , rubella and allergic skin reactions to drugs (drug exanthema).

For example, three-day fever does not begin with the symptoms of cough, runny nose and sensitivity to light, as is the case with measles.

With measles, unlike three-day fever, body temperature rises when the rash begins. In the case of three-day fever, on the other hand, the body temperature drops back to normal when the child develops the rash.

The typical rash associated with three-day fever first spreads to the trunk and rarely to the face. With measles and rubella it is exactly the opposite.


The three-day fever is treated purely symptomatically. If the temperature rises above 38.5 degrees Celsius during three-day fever, it helps if you wrap your child’s stomach or calves or give him fever-reducing medication such as paracetamol after consultation with the pediatrician. Children with three-day fever then usually feel better.

Even a small amount of clothing (e.g. only a diaper and bodysuit) helps to regulate body temperature. Make sure that your child drinks enough, because babies and toddlers in particular lose a lot of fluids due to the fever.

Febrile seizures are probably the result of the sudden rise in temperature. If they occur, you should lay your child on the floor so that they can breathe freely and do not injure themselves. Call your doctor right away and report the incident, even if the attack was brief and the child has subsequently recovered. He may recommend that the child be treated as an inpatient in the hospital.


In general: Consult your pediatrician if the child has a fever for more than three days, feels very ill or has a very high fever.

Course of the disease and prognosis

The prognosis is favorable for three-day fever. It usually passes quickly and children recover quickly after the fever has subsided. For many, the disease does not take the typical course described. The viral infection triggers only a weakened form of three-day fever, which often goes unnoticed.

If a febrile seizure occurs, this is often perceived as life-threatening. But: A febrile seizure does not count as epilepsy and does not leave any permanent damage in the child.

By the end of the second year of life, almost all children have gone through this viral infection – noticed or unnoticed. As a rule, the three-day fever leaves a lifelong immunity – exceptions are extreme situations for the immune system, such as an organ transplant. Then it is possible that the three-day fever occurs several times.

Complications are rare in three-day fever .

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