Phototherapy is a medically supervised dermatological treatment that uses specific wavelengths of ultraviolet (UV) light to manage chronic inflammatory and immune-mediated skin conditions. It is commonly indicated for psoriasis, vitiligo, eczema, chronic dermatitis, certain types of pruritus, cutaneous T-cell lymphoma (early stages), and other photo-responsive dermatoses. When administered in a controlled clinical setting, phototherapy provides an effective, non-invasive alternative to systemic medications while maintaining a strong safety profile.

The therapeutic mechanism of phototherapy involves controlled exposure to narrowband ultraviolet B (NB-UVB) or other specific light spectra that penetrate the skin and modulate immune responses. In inflammatory skin conditions such as psoriasis and eczema, immune overactivity drives excessive skin cell turnover and chronic redness. Targeted UV exposure slows abnormal keratinocyte proliferation, reduces inflammatory cytokines, and restores more balanced immune signaling. In pigmentary disorders like vitiligo, phototherapy stimulates melanocyte activity and repigmentation in affected areas.

Before initiating treatment, a comprehensive dermatological assessment is performed. This includes evaluation of diagnosis, disease severity, prior treatments, skin type, photosensitivity history, medication use, and contraindications. Treatment plans are individualized based on the patient’s skin phototype and clinical response potential. Baseline documentation helps monitor improvement and ensures safe cumulative dosing.

Phototherapy sessions are typically conducted two to three times per week. Each session lasts only a few minutes, with exposure time gradually increased according to tolerance and response. Protective eyewear is mandatory during treatment, and unaffected sensitive areas may be shielded. Patients are closely monitored for side effects such as mild redness, dryness, or transient irritation.

One of the key advantages of phototherapy is its steroid-sparing and systemic-medication-sparing effect. Many patients prefer phototherapy when topical treatments fail or when long-term oral immunosuppressants are not ideal. It may be used alone or in combination with topical therapies to enhance outcomes.

Long-term safety is carefully managed. Cumulative UV exposure is tracked to minimize the risk of premature photoaging or increased skin cancer risk. Education regarding avoidance of excessive natural sun exposure outside sessions is essential to prevent overexposure.

Results typically develop gradually over weeks of consistent therapy. Patients often experience reduction in inflammation, scaling, itching, and pigmentation irregularities. Maintenance therapy may be recommended for chronic conditions prone to recurrence.

Phototherapy offers structured, evidence-based disease control without surgical intervention. When delivered under dermatological supervision with individualized dosing protocols, it provides sustained improvement in chronic skin disorders and significantly enhances patient quality of life.