NB-UVB Dosing Calculator
Phototherapy Treatment Protocol
Calculates narrowband UVB (311-313 nm) treatment time from Fitzpatrick skin type and measured irradiance. Includes a session-by-session dose escalation schedule following AAD-NPF phototherapy guidelines.
About the NB-UVB
Clinical Background
NB-UVB phototherapy (311-313 nm) is a first-line treatment for moderate-to-severe psoriasis, vitiligo, atopic dermatitis, and other inflammatory dermatoses. Initial dosing can be determined by Fitzpatrick skin type: Types I-II start at 300 mJ/cm2 (max 2,000), Types III-IV start at 500 mJ/cm2 (max 3,000), and Types V-VI start at 800 mJ/cm2 (max 5,000). Doses are escalated by approximately 20% per session.
Treatment time is calculated from the fundamental relationship: Time (seconds) = Desired Dose (mJ/cm2) / Measured Irradiance (mW/cm2). Irradiance should be measured before each session or at regular intervals, as UV lamp output degrades over time. Fluorescent NB-UVB lamps (Philips TL-01) lose 30-40% of output in the first 200 operating hours, then stabilize.
Dose escalation should be guided by erythema response: if asymptomatic pink erythema occurs, hold at previous dose; if symptomatic erythema lasts longer than 24 hours, reduce by 10-20%; if erythema persists beyond 48 hours, withhold treatment and resume at the last non-erythemogenic dose.
References
- Elmets CA, Lim HW, Stoff B, et al.. Joint AAD-NPF guidelines of care for the management and treatment of psoriasis with phototherapy. J Am Acad Dermatol. 2019;81(3):775-804. doi:10.1016/j.jaad.2019.04.042
- Hauptman M, et al.. Narrowband-ultraviolet B phototherapy for psoriasis treatment in skin of color: a systematic review and meta-analysis. Photodermatol Photoimmunol Photomed. 2025;41:e70051. doi:10.1111/phpp.70051
- Cameron H, Dawe RS, Yule S, et al.. A randomized, observer-blinded trial of twice vs. three times weekly narrowband ultraviolet B phototherapy for chronic plaque psoriasis. Br J Dermatol. 2002;147:973-978. doi:10.1046/j.1365-2133.2002.04996.x
- Mehta D, Lim HW. Ultraviolet B phototherapy for psoriasis: review of practical guidelines. Am J Clin Dermatol. 2016;17(2):125-133. doi:10.1007/s40257-016-0176-6
Getting Started
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