What is the efficacy of red light therapy (RLT) for treating psoriasis?

Red Light Therapy for Psoriasis: Limited Evidence and Not a First-Line Treatment

Red light therapy is not recommended as a primary treatment for psoriasis, as there is insufficient evidence supporting its efficacy compared to established phototherapy modalities like narrowband UVB.

Established Phototherapy Options for Psoriasis

Phototherapy remains a mainstay treatment for psoriasis, with several well-studied modalities:

Narrowband UVB (NB-UVB)

• First-line phototherapy option for psoriasis 1
• More effective than broadband UVB with superior clearance rates 1
• Operates at 311-313 nm wavelength spectrum 1
• Mechanism: Decreases keratinocyte proliferation, reduces Langerhans cells, down-regulates Th17 cells, and induces T-cell apoptosis 1

Broadband UVB (BB-UVB)

• Traditional treatment used for over 75 years 1
• Less effective than NB-UVB with lower clearance rates 1
• Higher percentage of erythema-inducing wavelengths 1

PUVA (Psoralen + UVA)

• More effective for refractory psoriasis plaques 1
• FDA-approved since 1982 1
• Higher remission rates than NB-UVB (35% vs 12% at 6 months) 1
• Significant side effects: photosensitivity, nausea, headaches, and long-term skin cancer risk 1

Red Light Therapy Evidence

The evidence for red light therapy in psoriasis is limited and inconclusive:

• A 2012 small comparative study showed some improvement in psoriatic plaques with both blue and red light, but blue light demonstrated better improvement for erythema 2
• A 2023 pilot study using red/near-infrared emitting fabric showed subjective improvement in only 3 psoriasis patients who completed the study 3
• A 2019 expert review concluded that low-level light therapy (including red light) cannot be recommended for inflammatory skin diseases due to lack of well-controlled studies 4

Treatment Algorithm for Psoriasis

1. First-line phototherapy: Narrowband UVB (NB-UVB)

   • Dosing: Based on skin type or minimal erythema dose (MED)
   • Frequency: 3-5 times weekly for at least 3 months 5
   • Monitor: Monthly examinations by a dermatologist 1

2. For refractory cases: Consider PUVA if NB-UVB fails

   • Higher efficacy but increased side effect profile
   • Requires careful monitoring for adverse effects 1

3. For localized resistant lesions: Consider excimer laser (308 nm) 4

Important Considerations and Precautions

• Patient screening: Exclude those with lupus erythematosus, xeroderma pigmentosum, photosensitivity disorders, or history of melanoma 1
• Sun protection: Use physical sunscreens (zinc oxide/titanium dioxide) with SPF 30-50+ during phototherapy treatment 6
• Maintenance therapy: Consider for prolonged remission (55% vs 33% remission at 1 year with maintenance) 1
• Monitoring: Regular follow-up for efficacy assessment and side effect detection 1

Conclusion on Red Light Therapy

While red light therapy shows some promise in small studies, it lacks sufficient evidence to be recommended for psoriasis treatment. The established phototherapy modalities, particularly NB-UVB, have stronger evidence supporting their efficacy and safety profiles. Patients interested in red light therapy should be advised that it remains experimental and should not replace proven treatments for psoriasis.