☀️ PUVA vs NB-UVB Treatment Comparator Simulator

PUVA — Oral and Topical Psoralen Photosensitization

Psoralen molecules intercalate DNA and require UVA activation to work.

• Oral/topical: Psoralen route (8-MOP common agent)
• 1.5–2 h: Dosing window (before UVA exposure)
• 320–400 nm: UVA range (long-wave ultraviolet)
• High: Photosensitivity (eye/skin protection required)

How psoralen sensitization works

Placeholder: psoralen binds DNA and awaits UVA photoactivation.

UVA Deep Penetration Mechanism

UVA reaches deeper dermal layers than UVB, engaging sensitized cells.

• Deep dermis: Penetration depth (vs. shallow UVB)
• Mono/bi-functional: Crosslink type (psoralen-DNA adducts)
• T-lymphocytes: Target cells (and keratinocytes)
• ~20 min: Session length (typical exposure)

Depth of action

Placeholder: UVA travels past the epidermis into deeper skin layers.

NB-UVB — Narrowband UVB Without Photosensitizer

311nm UVB acts directly on epidermal cells, no pill required.

• 311 nm: Wavelength (narrowband peak)
• None: Sensitizer needed (simpler protocol)
• Epidermis: Penetration depth (shallower than UVA)
• Preferred: Pregnancy use (safer profile)

Direct epidermal action

Placeholder: NB-UVB triggers apoptosis of pathogenic T-cells directly.

Efficacy and Side-Effect Comparison

PUVA clears thicker plaques faster but carries more long-term risk.

• Faster: PUVA clearance (fewer sessions needed)
• Better: NB-UVB safety (lower carcinogenic risk)
• Skin cancer: PUVA long-term risk (cumulative dose linked)
• PUVA only: Nausea/GI effects (oral psoralen side effect)

Balancing speed against safety

Placeholder: efficacy and cumulative risk trade off between modalities.

Choosing Modality by Disease Severity

Severe thick plaques may favor PUVA; moderate disease favors NB-UVB.

• NB-UVB: Moderate disease (first-line choice)
• PUVA: Severe/thick plaques (deeper penetration helps)
• NB-UVB: Children/pregnancy (preferred safety profile)
• Limits apply: Cumulative sessions (lifetime dose tracked)

Matching therapy to patient

Placeholder: severity, skin type, and history guide the final choice.

Placeholder: shared decision-making weighs speed versus cumulative risk.