Starting Dose by Fitzpatrick Phototype
Baseline NB-UVB dose scales with skin phototype.
- I–VI: Phototypes (Fitzpatrick scale)
- ~100 mJ: Type I dose (lowest starting dose)
- ~300 mJ: Type VI dose (highest starting dose)
- ~20%: Increment step (per visit, typical)
Phototype lookup
Darker phototypes tolerate higher initial UV-B doses.
Always confirm phototype by patient history, not visual estimate alone.
Minimal Erythema Dose Reference Chart
MED anchors the starting dose calculation per patient.
- Lowest UV: MED definition (dose causing erythema)
- ~200 mJ/cm²: Type I MED (reference chart value)
- ~600 mJ/cm²: Type VI MED (reference chart value)
- Phototest: Test method (or phototype estimate)
MED chart use
Chart-based MED is used when phototesting is unavailable.
Measured MED is preferred over chart estimates when feasible.
Percentage-of-MED Starting Protocol
Standard protocols start at 50% of estimated MED.
- 50%: Standard start (of estimated MED)
- 25–30%: Conservative start (for sensitive patients)
- 10–20%: Increase per visit (if no erythema)
- ~40 mJ: Max increase cap (per session, typical)
Percent-based dosing
Dose escalation follows tolerance and erythema response.
Reduce percentage if prior erythema or missed sessions occurred.
Body Site Sensitivity Adjustment
Sensitive body sites require lower starting doses.
- Face, neck: High-sensitivity sites (and flexural areas)
- ~30%: Reduction factor (typical dose reduction)
- Trunk, limbs: Standard sites (full calculated dose)
- Genitalia: Shielding advised (routinely shielded)
Site-specific dosing
Adjust dose downward for thin or sensitive skin regions.
Sensitive-site burns are a leading cause of treatment interruption.
Initial Dose Confirmation
Final adjusted dose is confirmed before first exposure.
- Phototype +: Final check (site adjustment combined)
- Chart entry: Documentation (recorded per session)
- Each visit: Review interval (reassess tolerance)
- Built-in: Safety margin (below erythema threshold)
Confirmed starting dose
Adjusted dose is logged and used for session one.
Confirm no photosensitizing medications before starting treatment.