What is the condition where you get hives from something brushing up against your skin?

Symptomatic Dermographism: The Condition Where Hives Develop from Skin Contact

The condition where you get hives from something brushing up against your skin is called symptomatic dermographism (also known as dermatographism or factitious urticaria). This is a specific form of physical urticaria where mechanical stimuli like pressure or scratching trigger the development of wheals (hives) 1.

Understanding Symptomatic Dermographism

Symptomatic dermographism is characterized by:

• Red, raised, itchy wheals that develop within minutes after the skin is stroked, scratched, or subjected to pressure
• Wheals typically follow the exact pattern of the triggering stimulus (hence the name "dermographism" - literally "skin writing")
• Lesions usually resolve within 30-60 minutes without treatment
• Unlike other forms of urticaria, the wheals are directly induced rather than spontaneous

Pathophysiology

The mechanism involves:

• Mechanical stimulation triggering mast cell degranulation
• Release of histamine and other inflammatory mediators
• Increased vascular permeability in postcapillary venules
• Development of localized edema, erythema, and pruritus 2

Clinical Presentation and Diagnosis

Diagnosis is primarily clinical and can be confirmed with a simple provocation test:

• Stroking the skin with a blunt object (like a tongue depressor)
• Observing for the development of linear wheals along the stroke lines
• The wheals of symptomatic dermographism typically disappear within an hour 1, 3

Unlike other forms of urticaria that may last 2-24 hours, the wheals in symptomatic dermographism are characteristically short-lived. This helps distinguish it from other urticarial conditions 1.

Management Approach

Treatment follows a stepwise approach:

1. First-line therapy: Second-generation H1-antihistamines

   • Non-sedating options like fexofenadine 180mg, cetirizine 10mg, or loratadine 10mg daily 4
   • These have minimal sedation and a favorable safety profile

2. For inadequate response: Increase antihistamine dose

   • Doses can be increased up to 4 times the standard dose 4
   • For example, fexofenadine can be increased to 180mg four times daily

3. For resistant cases: Consider additional therapies

   • Add leukotriene receptor antagonists (e.g., montelukast)
   • For severe cases unresponsive to antihistamines, consider omalizumab or cyclosporine 4

Important Considerations

• Trigger avoidance: Minimize tight clothing, vigorous toweling after bathing, and other mechanical stimuli
• Emergency preparedness: While symptomatic dermographism rarely progresses to anaphylaxis, patients should stop antihistamine use and seek medical help if an allergic reaction occurs 5
• Prognosis: The condition may resolve spontaneously, but can persist for years in some patients

Special Populations

• Elderly: Avoid sedating antihistamines due to increased fall risk and cognitive impairment 4
• Children: The condition presents similarly in children and adults, but long-term oral corticosteroids should be avoided 4, 6

Symptomatic dermographism is a relatively common condition that, while not life-threatening, can significantly impact quality of life through persistent itching and visible skin changes. Proper diagnosis and management with antihistamines can effectively control symptoms for most patients.