What are the treatment options for sun allergy (photosensitivity)?

Treatment Options for Sun Allergy (Photosensitivity)

The primary treatment options for sun allergy include photoprotection, topical corticosteroids, antihistamines, and phototherapy, with PUVA therapy being particularly effective for severe cases of polymorphic light eruption (PLE), chronic actinic dermatitis (CAD), and solar urticaria (SU). 1

First-Line Treatments

• Photoprotection: Minimize sun exposure, especially during peak hours, and use high SPF sunscreens to reduce photosensitivity reactions 2
• Topical corticosteroids: Effective for managing acute flares and can be used prophylactically before sun exposure in susceptible individuals 1
• Antihistamines: High-dose H1 antihistamines are the standard therapy for solar urticaria, though many patients receive only modest benefit 1

Phototherapy Options

PUVA (Psoralen plus UVA) Therapy

PUVA therapy is particularly effective for several types of photosensitivity disorders:

• For Polymorphic Light Eruption (PLE):

  • Typically administered in early spring before natural sun exposure 1
  • Usually given twice weekly in the UK, with 12-20 treatments total 1
  • Risk of provoking PLE is high during initial treatments (12-50% of courses) 1
  • Provocation episodes can be managed with potent topical steroids and lower dose increments 1
  • Some protocols use oral prednisolone (40-50mg) for the first 2 weeks of phototherapy to prevent provocation 1

• For Chronic Actinic Dermatitis (CAD):

  • Should be performed under close supervision with topical or systemic corticosteroid cover 1
  • One approach uses prednisolone (20-30mg) on phototherapy days with small dose increments of 0.05 J/cm² 1
  • Treatment frequency: three times weekly initially, then reduced to twice weekly, then once weekly 1
  • Annual repeated courses can be considered, balancing benefits against skin cancer risk 1

• For Solar Urticaria (SU):

  • Requires determination of action spectrum and minimum urticarial dose (MUD) before starting 1
  • Initial dose should be lower than the MUD 1
  • For patients with very low MUD, UVA alone or pre-PUVA UVA desensitization has been used 1
  • Whole-body PUVA at 80% MUD, three times weekly for 4-8 weeks has shown increased sun tolerance 1

Other Phototherapy Options

• Narrowband UVB (NB-UVB):
  • Effective for solar urticaria with good tolerance 1
  • Reported 20% relapse rate at 3 months 1
  • No comparative trials between NB-UVB and PUVA are available 1

Advanced Treatment Options

• For refractory cases of Solar Urticaria:

  • Combination therapy of PUVA with plasmapheresis or intravenous immunoglobulins (IVIg) has shown increased sun tolerance 1, 2

• For severe Chronic Actinic Dermatitis:

  • Ciclosporin (5 mg/kg daily) in combination with PUVA and initial prednisolone has been reported effective 1
  • Mycophenolate mofetil (1g twice daily) with PUVA and initial prednisolone cover, followed by maintenance PUVA once weekly 1

Post-Treatment Management

• Continue natural sunlight exposure after phototherapy to maintain photoprotection 1
• Exposure recommendations range from 2 hours weekly to "cautious exposure with sunscreens for extended outdoor stay" 1
• Annual desensitization is not usually recommended due to potential long-term skin cancer risks 1

Special Considerations

• Timing of PUVA therapy is crucial - if administered too early in the year, photoprotective effect may subside by mid-summer; if too late, the patient may have already suffered an eruption 1
• For sunscreen allergies, identify the specific UV filter causing the reaction and advise patients to avoid products containing that ingredient 3
• Phototoxic reactions (resembling exaggerated sunburn) are more common than photoallergic reactions (resembling allergic contact dermatitis) 4

Treatment Algorithm

1. Mild cases: Photoprotection + topical corticosteroids + antihistamines 2
2. Moderate cases: Add prophylactic phototherapy before peak sun season 1
3. Severe cases: Consider PUVA with appropriate corticosteroid cover, potentially adding immunosuppressants for refractory disease 1