Psoriasis is a chronic skin condition characterized by an accelerated production of skin cells, leading to thick, red patches covered with silvery scales. These patches, known as plaques, can be itchy, uncomfortable, and sometimes painful. Ultraviolet B (UVB) phototherapy is a treatment that uses specific wavelengths of ultraviolet light to slow down this rapid skin cell growth and reduce inflammation.
Understanding UVB Therapy Sessions
UVB therapy sessions are carefully controlled. Initially, exposure times might be as short as several seconds, gradually increasing to a few minutes. This duration is determined by the specific dose required, varying by treatment area.
Treatment frequency typically involves sessions two to three times per week. Patients with moderate to severe psoriasis often require 20 to 36 sessions of narrowband UVB (NB-UVB) phototherapy for significant improvement. A minimum of 24 hours is required between sessions to allow skin response and prevent overexposure.
Individualized Treatment Planning
The overall duration of UVB therapy is highly individualized. Several factors influence the total course of treatment, including the severity and extent of the psoriasis. More widespread or severe cases may require a longer treatment period to achieve clearance.
Skin type, categorized using the Fitzpatrick scale, plays a significant role in determining the initial dose and subsequent adjustments. Patients with fairer skin types typically start with lower doses compared to those with darker complexions. Patient response is continuously monitored, with doses incrementally increased as tolerated to optimize results.
The type of UVB equipment also affects treatment planning. Narrowband UVB (NB-UVB) is preferred over broadband UVB (BB-UVB) for its greater effectiveness and safety profile, leading to faster skin clearance and longer remission periods. While clinic-based phototherapy is common, home UVB units are an option, requiring strict adherence to prescribed protocols and regular physician follow-ups.
Recognizing Treatment Endpoints
Healthcare professionals determine when to adjust or conclude UVB therapy by observing the patient’s skin response. The primary goal is “clearance,” meaning lesions significantly improve or disappear, often reaching a 90% or greater reduction in psoriasis extent. This typically occurs after 12 to 24 treatments.
Once significant clearing is achieved, phototherapy session frequency may be gradually reduced to a maintenance phase, such as once weekly, for long-term management. Treatment might also be paused or stopped if there is an insufficient response, or if adverse effects, such as excessive redness or discomfort, become problematic. The skin may remain clear for months after treatment is discontinued.
Managing Potential Effects
The duration and cumulative exposure to UVB light necessitate careful management of potential effects. Acute effects include sunburn-like reactions, mild stinging, or burning, especially if doses are not appropriately managed. While some redness is expected after a session, blistering is a rare but possible side effect.
Long-term considerations related to cumulative UVB exposure include premature skin aging, characterized by freckles, age spots, and wrinkles. Although studies have not consistently found a significant increased risk of skin cancer with NB-UVB phototherapy, the risk may correlate with the total number of treatments. Medical supervision is important to monitor for suspicious skin changes and ensure the benefits of treatment outweigh potential long-term risks.