Sun Allergies: Understanding Photodermatoses
Yes, you can be allergic to the sun, though true sun allergies (photodermatoses) are relatively uncommon conditions where the immune system reacts abnormally to ultraviolet (UV) radiation or visible light. 1 These conditions can significantly impact quality of life by limiting outdoor activities and causing uncomfortable symptoms.
Types of Sun Allergies
Several distinct photodermatoses exist:
1. Solar Urticaria (SU)
- Presentation: Rapid onset (minutes) of itching, weals, and erythema after sun exposure 1, 2
- Demographics: Affects both sexes, peak age between 20-30 years 2
- Duration: Nearly half of patients experience resolution within 5 years 2
- Triggers: Primarily visible light (67%) or UVA radiation (28%) 2
- Severity: Can be severe enough to restrict normal daily activities 3
2. Polymorphous Light Eruption (PLE)
- Presentation: Polymorphous skin eruptions that typically appear in spring 4
- Risk: High risk of provocation during initial phototherapy exposures (12-50%) 1
- Management: May require corticosteroid cover during treatment 1
3. Chronic Actinic Dermatitis (CAD)
- Presentation: Persistent eczematous reaction to light
- Management: Requires specialist care with knowledge of the patient's specific action spectrum 1
Distinguishing True Sun Allergies from Other Reactions
It's important to note that many people who believe they have "sunscreen allergies" are actually experiencing:
- Skin irritation rather than true allergic reactions 1
- Contact dermatitis to ingredients in sunscreens 5, 6
- Photocontact dermatitis when sunscreen ingredients interact with UV light 5
Research shows that true photoallergy to sunscreens is much less common than patients believe, with only a small percentage of self-reported "sunscreen allergies" confirmed through photopatch testing 6.
Diagnosis
Diagnosis of photodermatoses requires specialized testing:
- Photopatch testing: Essential for confirming photoallergic contact dermatitis 6
- Monochromator phototesting: Determines the action spectrum and minimum urticarial dose (MUD) 1
- Laboratory examinations: May show increased IgE in about 33% of solar urticaria patients 2
Management Approaches
Treatment options depend on the specific photodermatosis:
For Solar Urticaria:
- First-line: High-dose H1 antihistamines 1
- Phototherapy options:
- Refractory cases: Cyclosporin A (4.5 mg/kg/day) has shown success in severe cases resistant to other treatments 3
For Chronic Actinic Dermatitis:
- PUVA therapy with corticosteroid cover (prednisolone 20-30mg on treatment days) 1
- Small dose increments (0.05 J/cm²) with each exposure 1
- Gradual reduction from three times weekly to once weekly 1
Prevention Strategies
For individuals with photodermatoses:
- Sun avoidance: Particularly during peak hours
- Protective clothing: Hats, long sleeves, and UV-protective fabrics
- Shade seeking: Reduces direct UV radiation by up to 65% 1
- Sunscreens: As a complementary measure, though patients should be aware of potential allergens (benzophenone-3 and dibenzoyl methanes are common allergens) 1
Important Caveats
- Sunscreen selection: Patients with suspected sunscreen allergies should note active ingredients and try products with different chemical compositions 1
- Phototherapy risks: Treatment of photodermatoses with phototherapy carries risk of provocation, syncope, and even anaphylaxis 1
- Maintenance: The photoprotective effect of therapy diminishes several weeks post-treatment, requiring continued sun exposure or repeated courses 1
- Long-term risks: Repeated PUVA courses must be balanced against skin cancer risks 1
By understanding these conditions and implementing appropriate management strategies, patients with photodermatoses can significantly improve their quality of life and safely enjoy outdoor activities.