Photodermatoses (Sun Sensitivity) Support Protocol

Photodermatoses are skin conditions caused or worsened by exposure to light, usually sunlight. They range from common conditions like polymorphous light eruption to rare genetic disorders.

COMMON TYPES:

•Polymorphous Light Eruption (PMLE): Most common; itchy rash after sun exposure

•Solar urticaria: Hives from sun exposure

•Chronic actinic dermatitis: Severe sun sensitivity, usually in older men

•Erythropoietic protoporphyria (EPP): Genetic; severe pain with sun exposure

•Drug-induced photosensitivity: From medications

SYMPTOMS:

•Rash, bumps, or hives on sun-exposed skin

•Itching, burning, or stinging

•Redness

•Blisters (severe cases)

•Occurs shortly after sun exposure

COMMON PHOTOSENSITIZING MEDICATIONS:

•Tetracyclines (doxycycline)

•Thiazide diuretics

•NSAIDs

•Sulfonamides

•Some antipsychotics

•Some antidepressants

PREVENTION:

•Strict sun protection (sunscreen SPF 50+, reapply)

•Protective clothing (UPF-rated)

•Avoid peak sun hours (10am-4pm)

•Seek shade

•Review medications for photosensitizers

MEDICAL TREATMENTS:

•Desensitization phototherapy (for PMLE)

•Topical corticosteroids for rash

•Antihistamines for itching

•Afamelanotide (for EPP)

* Nicotinamide has strong evidence for reducing UV damage.

* Beta-carotene provides some photoprotection.

* Polypodium leucotomos is an oral photoprotectant.

Expected timeline: Supplements should be taken consistently; take beta-carotene for 10 weeks before sun season for EPP. Nicotinamide provides ongoing protection.

Clinical Perspective

Photodermatoses: Spectrum from common (PMLE ~10-20% prevalence) to rare (EPP). Classification: immunologically mediated (PMLE, solar urticaria), chemical/drug-induced, DNA repair defective (XP), metabolic (porphyrias). Diagnosis: photo-testing, history, appropriate investigations.

Treatment: Sun protection is cornerstone for all. PMLE: prophylactic phototherapy (desensitization) in spring. Solar urticaria: antihistamines, phototherapy. EPP: afamelanotide (Scenesse), beta-carotene. Drug-induced: remove offending agent. Supplements: nicotinamide has best evidence (ONTRAC trial); beta-carotene traditional for EPP/PMLE; Polypodium leucotomos emerging oral photoprotectant.

* Nicotinamide (A-grade): DNA repair. ONTRAC: (PMID: 26488693). 500mg BID.

* Beta-Carotene (B-grade): Photoprotection. Systematic review: (PMID: 7728700). 25-180mg daily.

* Polypodium Leucotomos (B-grade): Oral photoprotectant. Systematic review: (PMID: 27624749). 240-480mg daily.

* Vitamin E (C-grade): Antioxidant. Review: (PMID: 23075608). 400-800 IU daily.

* Vitamin C (C-grade): Antioxidant. Review: (PMID: 23440782). 500-1000mg daily.

* Omega-3 (C-grade): Anti-inflammatory. Review: (PMID: 27840029). 2-4g EPA+DHA daily.

Assessment targets: Symptom frequency/severity, minimal erythema dose (MED), quality of life.

Protocol notes: Sun protection: SPF 50+ broad spectrum; UPF clothing; reapply sunscreen q2h. PMLE: often improves with hardening (gradual exposure); prophylactic NBUVB in spring. Nicotinamide: shown to reduce actinic keratoses, skin cancers in high-risk; different from niacin (no flushing). Beta-carotene for EPP: 120-180mg daily; may take 10 weeks to be effective; skin turns slightly orange. Polypodium leucotomos: take with meals; 2h before sun exposure for acute protection. Drug-induced: review all medications; check package inserts. Lupus: can have photosensitivity; needs different management. XP: DNA repair disorder; requires extreme photoprotection; dermatology/genetics involvement. Photo-testing: helps identify action spectrum and diagnosis.

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