Though less common, a person with miliaria rubra may ... and their skin isn’t used to rapidly changing temperatures. Like most baby rashes, prickly heat is usually harmless and will go away ...
Armpit rashes can be caused by allergic reactions, infections, and chronic conditions. Armpits are a common place to get rashes because the skin there is thin, folds up on itself, and can be hairy.
Miliaria profunda: This is the least common type of heat rash. It forms in the deepest layer of skin, and it can recur and become chronic. It causes relatively large, tough, flesh-colored bumps.
It can be itchy, red or purple, or painful. Most people who have HIV get a rash at some point. It’s a common symptom that can happen in early (acute) or later stages of an HIV infection.