Prickly heat is also known as sweat retention syndrome or miliaria rubra.
Miliaria crystallina is the most superficial of the occlusions.
Deeper plugging causes miliaria rubra as the sweat seeps into the living layers of skin, where it irritates and itches.
Miliaria pustulosis (a complication of miliaria rubra) occurs when the sweat is infected with pyogenic bacteria and turns to pus.
Infants are more likely to get miliaria rubra than adults.