What is miliaria?

Updated: Mar 27, 2020
  • Author: Nikki A Levin, MD, PhD; Chief Editor: Dirk M Elston, MD  more...
  • Print
Answer

Miliaria is a common disorder of the eccrine sweat glands that often occurs in conditions of increased heat and humidity. Miliaria is thought to be caused by blockage of the sweat ducts, which results in the leakage of eccrine sweat into the epidermis or dermis. [1, 2] Note the image below.

Miliaria crystallina in an infant. Note that the l Miliaria crystallina in an infant. Note that the lesions are confluent. Courtesy of K.E. Greer, MD.

See 13 Common-to-Rare Infant Skin Conditions, a Critical Images slideshow, to help identify rashes, birthmarks, and other skin conditions encountered in infants.

The 3 types of miliaria are classified according to the level at which obstruction of the sweat duct occurs. In miliaria crystallina, ductal obstruction is most superficial, occurring in the stratum corneum. Clinically, this form of the disease produces tiny, fragile, clear vesicles. In miliaria rubra, obstruction occurs deeper within the epidermis and results in extremely pruritic erythematous papules. In miliaria profunda, ductal obstruction occurs at the dermal-epidermal junction. Sweat leaks into the papillary dermis and produces subtle asymptomatic flesh-colored papules. When pustules develop in lesions of miliaria rubra, the term miliaria pustulosa is used. Note the images below.

Miliaria pustulosa. Courtesy of K.E. Greer, MD. Miliaria pustulosa. Courtesy of K.E. Greer, MD.
Miliaria pustulosa. Courtesy of K.E. Greer, MD. Miliaria pustulosa. Courtesy of K.E. Greer, MD.

Miliaria rubra can cause great discomfort, and miliaria profunda may lead to heat exhaustion. Treatment of these conditions is warranted. See Heat Illness: How To Cool Off Hyperthermic Patients, a Critical Images slideshow, for tips on treatment options for these patients.


Did this answer your question?
Additional feedback? (Optional)
Thank you for your feedback!