Heat Rash (Miliaria): Clinical Presentation and Management
Heat rash is a self-limiting condition caused by sweat duct obstruction that presents with characteristic vesicles or papules, and treatment focuses on cooling, removing occlusive factors, and maintaining skin hygiene—with most cases resolving spontaneously within days to a week. 1, 2
Clinical Presentation and Types
Heat rash manifests differently depending on the level of sweat duct obstruction:
Miliaria Crystallina
- Clear, fragile, superficial vesicles (1-3 mm) resembling water droplets on the skin surface 3, 4
- Occurs due to obstruction in the stratum corneum (most superficial layer) 2
- Most benign form, typically seen in febrile patients 2, 4
- Heals spontaneously within hours to days, followed by fine desquamation 2
Miliaria Rubra (Prickly Heat)
- Red, itchy papules or vesicles on an erythematous base 1
- Results from obstruction within the malpighian stratum (deeper in epidermis) 2
- Associated with pruritus and discomfort 1
- Can progress to moderate-to-severe irritation, particularly with prolonged exposure 1
- May become superinfected with Staphylococcus species, requiring medical attention 1
Miliaria Profunda
Predisposing Factors
The condition develops from:
- Hot, humid environments (temperatures 39-50°C documented in occupational cases) 1
- Occlusive clothing, particularly synthetic or blend fabrics 1
- Fever and hyperthermia 2, 4
- Excessive sweating with inadequate evaporation 1, 3
- Poor hygiene or infrequent clothing changes 1
Immediate Management
Cooling Measures
- Move to a cool environment immediately and remove excess clothing 5, 6
- Apply passive cooling with cool water spray or wet towels to affected areas 6
- Ensure adequate ventilation of the skin 4
Skin Care
- Keep affected areas dry and clean through regular hygiene 1
- Change clothing frequently, especially if perspiration-soaked 1
- Remove occlusive garments or fabrics causing the condition 1
Topical Treatment
- Topical corticosteroids may be used for symptomatic relief in miliaria rubra with significant inflammation 1
- Most cases resolve without specific medication 2, 4
Critical Warning Signs
Seek medical attention if:
- Signs of secondary bacterial infection develop (crusting, weeping, increased pain, spreading erythema) 1
- Symptoms persist beyond one week despite appropriate measures 1
- Extensive bullous lesions develop (rare but documented) 3
- Associated systemic symptoms suggest heat exhaustion (nausea, dizziness, altered mental status) 5, 6
Prevention Strategies
- Wear loose-fitting, breathable cotton clothing rather than synthetic or occlusive fabrics 6, 1
- Maintain good personal hygiene with regular bathing 1
- Avoid prolonged exposure to hot, humid environments when possible 1, 4
- Thoroughly launder clothing to remove detergent residue, which can contribute to skin irritation 1
- Acclimatize gradually to hot environments over 12-14 days if occupational exposure is necessary 6
Common Pitfalls
- Failing to recognize superimposed bacterial infection in miliaria rubra, which can become serious if untreated 1
- Continuing to wear occlusive or irritating fabrics despite symptoms 1
- Confusing miliaria crystallina with other vesicular conditions—the clear, superficial, fragile nature and association with heat/fever are diagnostic 2, 4
- Not allowing adequate time for resolution—miliaria rubra can take a week or longer to clear completely 1