Light Therapy for Psoriasis: How It Works and What to Know

Disclaimer: This article shares general insights and common experiences from people living with psoriasis. It is not medical advice—always consult your dermatologist or healthcare provider before starting any light therapy, as it requires professional supervision and may not be suitable for everyone.

Light therapy (also called phototherapy) is one of the most established and effective non-systemic treatments for moderate to severe psoriasis. It uses controlled ultraviolet (UV) light to slow the rapid skin cell growth that causes plaques, reduce inflammation, and improve scaling, redness, and itch.

Main Types of Light Therapy

• Narrowband UVB (NB-UVB) — The most common and preferred type. It uses a specific wavelength (311–313 nm) that targets psoriasis effectively with fewer side effects than older broadband UVB. Sessions are typically 2–3 times per week in a clinic or at home (with a prescription device). Many people see significant clearing (often 75% or more improvement) after 20–30 sessions, with maintenance treatments as needed.

• PUVA (Psoralen + UVA) — Combines a light-sensitizing medication (psoralen) with UVA light. It's effective for thicker plaques but carries higher risks (e.g., skin aging, increased skin cancer risk with long-term use) and is used less often today.

• Excimer Laser — A targeted form of UVB delivered in high doses to small areas (great for stubborn spots like scalp, knees, or elbows). It requires fewer sessions and minimizes exposure to healthy skin.

Home phototherapy units (NB-UVB panels or handheld devices) are available with a prescription and can be more convenient for ongoing management. Studies show home NB-UVB is as effective as clinic-based treatment for many people, with good safety when monitored.

Benefits and Considerations

• Effectiveness — Phototherapy often achieves PASI 75 (75% improvement) in 60–80% of patients with moderate-severe psoriasis.

• Side Effects — Mild burning, redness, or itching during early sessions; long-term risks include premature skin aging and slight increased skin cancer risk (especially with PUVA).

• Who It's Best For — People with widespread plaques who don't respond well to topicals or prefer to avoid systemic medications.

Many find combining light therapy with moisturizers and gentle skin care enhances results and comfort.

Here are examples of what phototherapy sessions and home devices typically look like:

Light therapy remains a cornerstone of psoriasis care—safe, effective, and often covered by insurance when prescribed.

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