Table IV. Dosing Guidelines for Narrowband UVB.

According to skin type:
Skin Type	Initial UVB dose (mJ/cm2)	UVB Increase After Each Treatment (mJ/cm2)	Maximum dose (mJ/cm2)
I	130	15	2000
II	220	25	2000
III	260	40	3000
IV	330	45	3000
V	350	60	5000
VI	400	65	5000

According to MED:
Initial UVB	50% of MED
Treatments 1 -20	Increase by 10% of initial MED
Treatment ≥ 21	Increase as ordered by physician

If subsequent treatments are missed for:
4-7 d	Keep dose same
1-2 wk	Decrease dose by 25%
2-3 wk	Decrease dose by 50% or start over
3-4 wk	Start over

Maintenance therapy for NB-UVB after >95% clearance:
1×/ wk	NB-UVB for 4 wk	Keep dose same
1×/ 2 wk	NB-UVB for 4 wk	Decrease dose by 25%
1×/ 4 wk	NB-UVB	50% of highest dose

MED, Minimal erythema dose; NB, narrowband; UV, ultraviolet.

Administered 3-5×/wk.

Because there is broad range of MED for NB-UVB by skin type, MED testing is generally recommended. It is critically important to meter UVB machine once weekly. UVB lamps steadily lose power. If UV output is not periodically measured and actual output calibrated into machine, clinician may have false impression that patient can be treated with higher doses when machine is actually delivering much lower dose than number entered. Minimum frequency of phototherapy sessions required per week for successful maintenance as well as length of maintenance period varies tremendously between individuals. Above table represents most ideal situation where patient can taper off phototherapy. In reality, many patients require 1×/wk NB-UVB phototherapy indefinitely for successful long-term maintenance.

Reprinted from Journal of the American Academy of Dermatology, Volume 62, Menter A, Korman NJ, Elmets CA, Feldman SR, Gelfand JM, Gordon KB et al., Guidelines of care for the management of psoriasis and psoriatic arthritis. Section 5. Guidelines of care for the treatment of psoriasis with phototherapy and photochemotherapy, pages 114-135, Copyright 2010, with permission from the American Academy of Dermatology.