Wed. Jul 24th, 2024
Rash in infants: what are its causes?

The rash in infants appears due to different causes, especially viral. We tell you what some of them are.

The rash in infants presents as a reddish skin rash, which may be raised but never vesicles or blisters.

It is important not to confuse it with a simple erythema, in which the skin turns red due to cutaneous vasodilation. In this case, the skin never rises and the stain disappears when you press it with your finger and reappears when you remove it.

The appearance of the rash in infants will guide medical staff in making a diagnosis. The main types of rash are:

  • Scarlatiniform: Large red spots with a shiny, grainy appearance that are hot when you touch them. They can give a burning sensation and their appearance evolves towards scaly skin.
  • Morbilliform: Pink spots and elevations of various sizes, which can converge.
  • Rubeoliform: Pale pink streaks that do not converge with each other. The spots are lighter and less diffuse than in the case of morbilliform rash.
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The age of babies is important in recognizing rashes. Most of those that appear in boys and girls under 4 years of age are due to infections by  enteroviruses , adenoviruses , or herpesviruses 6 and 7 . On the other hand, the prevalence of meningococcal disease is higher below 2 years of age than at any other time in life.


Enterovirus  infections  occur most often in babies under 2 years of age, although they can also affect children and adults.

The younger the baby’s age, the more likely it is that a rash will develop. Therefore, in this case, the frequency of occurrence of rash in infants will be high. Some of its features are:

  • Maculopapular or macular rashes that can affect the palms of the hands and the soles of the feet.
  • The most common is that they are accompanied by fever. Enderoviruses  are the most common  cause of fever without a source in infants. They are also the most common cause of aseptic meningitis.

Herpes simplex virus type 6

Another virus that causes rash in infants is  Herpesvirus hominis type 6, which mainly affects babies under 2 years of age, especially those between 6 and 12 months. Some of its features are:

  • Appearance of sudden rash. 2 to 4 days of fever along with pink pimples, which start out on the chest and later spread to the face, abdomen, and to a lesser extent, the extremities. The rash lasts between 1 and 2 days.
  • Redness of the eardrum.

Herpes simplex virus type 7

It occurs at slightly older ages than Herpesvirus hominis type 6 infections  . Characteristics:

  • Sudden rash.
  • Fever along with rash.


Adenovirus  especially  affects boys and girls under 4 years of age. Characteristics:

  • Appearance of maculopapular rashes.
  • Fever.
  • Respiratory symptoms such as pharyngitis that can be exudative, cough and conjunctivitis. It can be confused with measles .

hemorrhagic edema of infancy

It is a disease that affects babies from 4 months to 2 years of age. Some of its features are:

  • Appearance of red erythematous edema.
  • Purpuric lesions on extremities, cheeks, chin and ears. They do not affect the trunk.

Unilateral chest rash

The lesions last 3 to 6 weeks and occur mainly in infants and children under 6 years of age. Characteristics:

  • Eruption that begins in the neck or in the armpits and that spreads maintaining a unilateral predominance in the thorax (it can also pass to the other side).
  • The lesions are scarlatiniform or eczematous, and may occasionally appear near the groin.
  • Up to 40% of infants and children who suffer from this rash also have: fever, conjunctivitis, nasopharyngitis or diarrhoea.

drug reactions

Some medications can cause skin reactions, leading to drug-induced rashes. Its appearance is usually purpuric or in the form of petechiae.