Heat & Occlusion-Related Skin Eruptions

Two eruptions triggered or worsened by heat, sweating and occlusion, despite different underlying mechanisms.

Miliaria (heat rash / sweat rash)

Blocked sweat glands causing inflammation. Common in hot climates and in the neonatal period; made worse by sudden exposure to a hot environment or occlusion of skin with a non-porous dressing.

Demographics: neonates (affects 9%) at around 1 week of age; also occurs in adults with fever.

History and examination: can cause itch and a prickly feeling (“prickly heat”). 1–2mm superficial, clear blisters that break easily, typically on the trunk and upper back.

Management: avoid hot, humid environments; calamine lotion can relieve discomfort; treat secondary infection if present. Mostly resolves within a day or two of moving to a cooler environment.

Grover disease

Typically affects men aged 70–80. Intensely itchy; triggered by heat, sweating, fever, or occlusion.

Examination: multiple small, firm, warty papules on the upper trunk — especially on sun-damaged skin.

Investigations: diagnosis by biopsy.

Management: relieve itch until spontaneous resolution; topical steroids or UV light.