AAD and NPF Guidelines Reinforce Phototherapy as a Safe, Effective Psoriasis Treatment
The American Academy of Dermatology (AAD) and the National Psoriasis Foundation (NPF) have jointly released updated clinical guidelines that reinforce the use of phototherapy as a highly effective treatment for moderate to severe psoriasis. The guidelines highlight phototherapy’s value as both a first-line therapy and a complementary option for patients who cannot tolerate systemic or biologic medications.
The full AAD and NPF phototherapy guidelines offer in-depth, evidence-based recommendations on treatment protocols, dosing strategies, and safety considerations for light-based therapies.
Read the full guidelines here.
Why Consider Phototherapy for Psoriasis?
While systemic and biologic treatments are commonly prescribed for psoriasis, they often come with a range of side effects or contraindications. Many patients may prefer to avoid them altogether. The new guidelines underscore that phototherapy is a clinically proven, well-tolerated treatment option for:
- Patients who do not respond well to topical therapies
- Individuals who prefer to avoid systemic medications
- Cases where phototherapy can complement an existing regimen
“Phototherapy serves as a reasonable and effective treatment option for patients requiring more than topical medications and/or those wishing to avoid systemic medications or simply seeking an adjunct to a failing regimen.” — AAD/NPF Guidelines
What Is Narrowband UVB (NB-UVB) Phototherapy?
Among all phototherapy modalities, Narrowband UVB (NB-UVB)—which emits ultraviolet light at 311–313 nanometers—is considered the most effective and widely used treatment for psoriasis.
Benefits of NB-UVB:
- Targeted wavelength minimizes the risk of burning
- Proven results with regular treatment
- Can be administered in-office or at home
Recommended Treatment Frequency:
- 2 sessions per week: Average clearance in 88 days
- 3 sessions per week: Faster clearance, ~58 days
A thin application of emollient (e.g., petrolatum) before each session can improve UV absorption and reduce irritation. However, thick application may block UVB light and reduce efficacy.
How to Start NB-UVB Treatment: Dosing by Skin Type or MED
The guidelines outline two approaches to establishing an initial NB-UVB dose:
1. Based on Skin Type (Fitzpatrick Scale)
| Skin Type | Description | Starting Dose |
| I–II | Very fair to fair | 300 mJ/cm² |
| III-IV | Light to medium | 500 mJ/cm² |
| V-VI | Dark to very dark | 800 mJ/cm² |
2. Based on Minimal Erythema Dose (MED) Testing
MED is the smallest amount of UVB light that causes redness in the skin 24 hours post-exposure.
How to perform MED testing:
- Use a test patch on a sun-protected area (e.g., buttock or hip).
- Deliver UVB in increasing increments using a MED patch or grid.
- After 24 hours, determine which area shows the first visible erythema.
- That dose is your patient’s MED.
Note: For skin types V and VI, MED testing is not typically recommended. Begin treatment at 800 mJ/cm² and increase gradually as tolerated.
Adjusting NB-UVB Dosage Over Time
According to the AAD and NPF guidelines, adjust phototherapy dosing based on the patient’s erythema response:
| Skin Reaction | Recommended Dose Adjustment |
| Mild erythema < 24 hours | Increase dose by 20% |
| Erythema lasting 24–48 hours | Maintain previous dose |
| Erythema > 48 hours | Skip treatment; resume last tolerated dose |
Managing Missed Treatments
When patients miss appointments, follow this approach:
| Days Missed | Dosing Adjustment |
| <1 week | Continue same dose |
| 1–2 weeks | Reduce dose by 25% |
| 2–4 weeks | Reduce dose by 50% |
| 4 weeks | Restart at initial dose |
Maintenance Therapy After Clearance
Once the patient achieves full or near-full skin clearance, maintenance therapy can help prolong remission:
- Treat every 1–2 weeks
- Reduce the final dose by 25%
- Keep the dose consistent for maintenance sessions
Phothera Phototherapy Devices: Clinical and Home Solutions
At Phothera, we support providers and patients with advanced phototherapy equipment tailored to your needs. Our devices are designed to deliver NB-UVB, UVA, and broadband UVB light therapy, and feature SmartTouch™ software that allows you to customize treatment protocols in accordance with AAD/NPF guidelines or your own clinic’s specifications.
Whether you’re a dermatologist offering in-office treatment or helping patients transition to home phototherapy, Phothera is your trusted partner in care.
Ready to incorporate phototherapy into your practice or help patients access home treatment options?
Contact us today to learn more.