Heat rash, also known as prickly heat and miliaria, isn’t just for babies. Though it’s common in infants, heat rash can affect adults, too, especially during hot, humid weather.


Heat rash develops when some of your sweat ducts become clogged. Instead of evaporating, perspiration remains trapped beneath the skin, causing inflammation and rash.

It’s not always clear why the sweat ducts become blocked, but certain factors seem to play a role, including:

  • Immature sweat ducts. 
  • Tropical climates. 
  • Physical activity. 
  • Certain fabrics. .
  • Medications. 
  • Overheating. 
  • Heavy creams and ointments. 


Adults usually develop heat rash in folds of skin and wherever clothing causes friction. In infants, the rash is mainly found on the neck, shoulders and chest, but it can also occur in the armpits, elbow creases and groin area.

There are three types of miliaria, which are classified according to where the sweat ducts are blocked. Signs and symptoms for each type vary.

Miliaria crystallina

The mildest form of heat rash affects the sweat ducts in the topmost layer of skin. Miliaria crystallina is marked by:

  • Clear, fluid-filled blisters and bumps that break easily

Miliaria rubra

Occurring deeper in the outer layer of skin, miliaria rubra is sometimes called prickly heat. Signs and symptoms typically include:

  • Red bumps
  • Itchy or prickly feeling in the affected area
  • Little or no sweating in the affected areas

Miliaria profunda

It affects a deeper layer of skin, and appears soon after exercise or any activity that causes sweating. Signs and symptoms may include:

  • Firm, flesh-colored lesions that resemble goose bumps
  • A lack of perspiration, which may lead to symptoms of heat exhaustion, such as dizziness, nausea and a rapid pulse

Home remedies:

  • In hot weather, dress in loose, lightweight clothing that wicks moisture away from your skin.
  • Spend as much time as possible in air-conditioned buildings.
  • After bathing, let your skin air-dry, instead of toweling off.
  • Use calamine lotion or cool compresses to calm itchy, irritated skin.
  • Avoid using creams and ointments, which can block pores further.

A heat rash is very common, especially in those hot summer months. Dress lightly and try to stay cool and in the shade.