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Miliaria rubra in Adult
Other Resources UpToDate PubMed

Miliaria rubra in Adult

Contributors: Haya Raef MD, Noah Craft MD, PhD, Susan Burgin MD
Other Resources UpToDate PubMed

Synopsis

Miliaria rubra, also known as heat rash or prickly heat, is an eruption caused by blockage of the eccrine sweat ducts. The resultant sweat retention and the escape of sweat into the dermis evokes an inflammatory response that manifests as papules. Resident bacteria (Staphylococcus spp) on the skin may also play a role. It is a benign and usually self-limited disease characterized by intense pruritus and a stinging or "prickly"-type sensation.

Miliaria is often related to conditions of high fever or high ambient temperatures with resulting hyperhidrosis, and it is more prevalent in hot, humid conditions and tropical climates. It is a common phenomenon postoperatively and in bedridden and febrile patients. Tight clothing and transdermal drug patches have also been associated with miliaria due to occlusion of the skin. Additionally, medications that induce sweating, such as the cholinergic drugs neostigmine and bethanechol, have been linked to the development of miliaria. A few cases of miliaria occurring in patients treated with isotretinoin have been reported.

There are different types of miliaria, each classified by the depth of occlusion of the eccrine duct:
  • Miliaria crystallina results from superficial obstruction of the eccrine duct within the stratum corneum. It presents as superficial vesicles with no surrounding erythema.
  • Miliaria rubra is caused by obstruction of the eccrine duct within the epidermis. It is the most prevalent form of miliaria and is characterized by 2-4 mm erythematous and uniform papules or papulovesicles with background erythema.
  • Miliaria pustulosa is a variant of miliaria rubra that occurs when pustules form and may indicate superimposed infection.
  • Miliaria profunda results from deeper obstruction of the sweat duct at the dermal-epidermal junction. It presents as skin-colored papules with possible associated hypohidrosis or anhidrosis.

Codes

ICD10CM:
L74.0 – Miliaria rubra

SNOMEDCT:
72658003 – Miliaria rubra

Look For

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Diagnostic Pearls

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Differential Diagnosis & Pitfalls

  • Miliaria rubra is often mistaken for a Exanthematous drug eruption, especially after a new antibiotic is started in a febrile patient.
  • Other miliaria variants – Miliaria crystallina, Miliaria pustulosa, Miliaria profunda.
  • Candidiasis – Often has some pustules.
  • Scabies – Unlike miliaria, often involves acral sites; check for the presence of burrows in the finger webs.
  • Varicella – Presents as vesicles on an erythematous base ("dewdrops on a rose petal"), and lesions are in different stages of development.
  • Folliculitis – Has follicular-based pustules.
  • Acne vulgaris – Can also be worsened by occlusion but usually lacks pruritus and is less acute.
  • Acute generalized exanthematous pustulosis (AGEP) – Is more diffuse with widespread pustules.
  • Transient acantholytic dermatosis – Also flares on the back of hospitalized patients with resulting very pruritic papules and erosions.
  • Cholinergic urticaria

Best Tests

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Management Pearls

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Therapy

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References

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Last Reviewed:09/03/2023
Last Updated:09/14/2023
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Miliaria rubra in Adult
A medical illustration showing key findings of Miliaria rubra (Adult) : Fever, Pruritus
Clinical image of Miliaria rubra - imageId=2037503. Click to open in gallery.
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