Miliaria (Heat Rash, Prickly Heat)

Last updated 10.12.13



-  Epidermal or dermal skin rash from obstruction of eccrine sweat glands



-  Sweat glands become blocked & sweat accumulates under the skin causing mild inflammation

- Typically lasts hours to days & is self limiting

-  If significant area effected can contribute to heat exhaustion/strok due to impaired hearing



-  Miliaria crystilline (clear): vesicles only

-  Miliaria rubra (red): larger blisters with inflammation & sensation = prickly heat

- Miliaria pustulosa (yellow): when pus accumulates in blisters

- Miliaria profunda (deep): chronic effect, effects dermis, causes deeper, harder, larger lumps


Miliaria Crystilline


Miliaria Rubra


Miliaria Pustulosa


Risk Factors

-  Humid environments

- Opposed areas of skin: creases, etc,

- Non-breathable &/or tight clothing, bandages, patches

- Excessive sweating

- Heavy creams or lotions: sunscreen, make up

- Medications: Clonidine, Isotrenitoin

- Newborns (fever, excessive clothing, warm weather), elderly

- Type 1 pseudohypoaldosteronism


Associated S/S

-  Rash: erythematous vesicles

-  Any body part but typically face, neck, back, abdomen, groin, elbow folds, buttocks, submammary

-  Prutitus or prickly sensation: may feel similar to sunburn



-  Secondary infection = miliaria pustulosa

-  Heat related injury: heat exhaustion, heat stroke

- Heat intolerance: weakness, fatigue, dizziness (topical anhydrous asthenia)



-  Candida

-  Folliculitis


- Chicken Pox (Varicella)

- Erythema toxicum neanatorum



-  Typically not required

-  Consider biopsy if usure or atypical features



-  Cooling of effected pars

- Avoid trigger: creams, meds..

- Topical agents

-  Calamine lotion

-  Hydrocortisone

- Anhydrous lanoline for miliaria profunda

-  +/- Antibiotics if secondary infection

- Prevention

-  Breathable loose fabrics: cotton

- Air conditioning

- Keep skin clean with frequent washing

- Adequate hydration

- Acclimitisation






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MedicineNet: Heat Rash

Pic: Miliaria crystiline

Pic: Miliaria rubra

Pic: Miliaria pustulosa