Is it normal to experience pruritus and rash with diaphoresis (excessive sweating)?

From the Guidelines

It's not typically normal to experience pruritus and rash with diaphoresis, as this could be a symptom of an underlying condition such as cholinergic urticaria or exercise-induced anaphylaxis. According to the study published in the Journal of Allergy and Clinical Immunology 1, cholinergic urticaria is a physical allergy characterized by the development of punctate, intensely pruritic wheals with erythematous flaring after an increase in core body temperature or stress. This condition is often associated with an increase in core body temperature without vascular collapse.

Key Considerations

• A detailed history of symptoms associated with the first episode, as well as previous attacks, should be obtained to determine the underlying cause of the symptoms.
• Particular attention should be given to the antecedent use of aspirin or other nonsteroidal anti-inflammatory agents, as well as any seasonality to the attacks.
• Early recognition of the prodromal manifestations of exercise-induced anaphylaxis is extremely important, with discontinuation of exercise at the earliest symptom.

Management and Treatment

• For mild cases, over-the-counter antihistamines like cetirizine (10mg daily) or loratadine (10mg daily) can help manage symptoms.
• For immediate relief of itching, apply cool compresses to affected areas and wear loose, breathable clothing during activities that cause sweating.
• If symptoms are severe or persistent, prescription-strength antihistamines or medications like hydroxyzine (25mg as needed) might be necessary.
• Some people benefit from gradual heat acclimation through regular exercise to reduce reactions over time.

When to Seek Medical Attention

• If symptoms include difficulty breathing, facial swelling, or dizziness, seek immediate medical attention as these could indicate a more serious allergic reaction.
• The emergency management of exercise-induced anaphylaxis is the same as that of anaphylaxis of other causes, with early administration of epinephrine being essential 1.

From the Research

Pruritus and Rash with Diaphoresis

• Pruritus, or itch, can be associated with diaphoresis (excessive sweating) in certain circumstances, such as in individuals with atopic dermatitis (AD) 2.
• In AD, attenuated sweating ability can lead to heat retention, skin dryness, and increased susceptibility to itch, which can be exacerbated by diaphoresis 2.
• The relationship between sweat and itch is complex, and recent evidence suggests that sweat with elevated glucose concentration can retard the recovery of the damaged skin barrier and promote itching 2.
• Diaphoresis can also lead to miliaria, a condition characterized by small, itchy bumps on the skin, which can cause pruritus and rash 2.

Treatment of Pruritus and Rash

• Antihistamines, such as H1 antihistamines, are commonly used to treat pruritus, but their efficacy in treating pruritus associated with diaphoresis is limited 3, 4, 5.
• Topical treatments, such as corticosteroids and antibiotics, may be more effective in treating pruritus and rash associated with diaphoresis, especially in individuals with AD or other skin conditions 6.
• Oral H1 antihistamines may be used as add-on therapy to topical treatment for eczema, but their effectiveness is not well established, and more research is needed to determine their efficacy 5.

Mechanisms of Pruritus and Rash

• Histamine is thought to play a key role in the pathogenesis of pruritus, but the exact mechanisms are not fully understood 4.
• The scratch reflex, which is a common response to itching, can damage the epidermal layer of the skin and lead to increased transepidermal water loss and drying, which can exacerbate pruritus and rash 4.
• The relationship between sweat, itch, and skin barrier function is complex, and further research is needed to understand the underlying mechanisms and develop effective treatments for pruritus and rash associated with diaphoresis 2, 5.