Everything Dermatologists Need to Know About UV Therapy

The use of light in dermatology for the treatment of skin disorders, otherwise known as UV or phototherapy, has been proven to improve various cutaneous conditions. By emitting and exposing patients to specific wavelengths of light, the technology works to slow down cell growth and inflammation – factors that cause many skin problems to develop. When carefully controlled, UV therapy can be a very effective outpatient treatment tool for cutaneous disease, working to mitigate symptoms and greatly enhance appearance of skin in cases of psoriasis, vitiligo, scleroderma, and other dermatologic disorders.

The Long History of UV Therapy

The phototherapy method has a long history of many uses. Medical light therapy for the treatment of skin disease can be traced back to 1877, when research reported that light exposure was able to inhibit fungal growth in a test tube study. Continuing evidence sparked a growing interest in the effects of light on parasitic skin disease and culminated in Niels Finsen being awarded the 1903 Nobel Prize in Medicine for his pioneering work. Finsen demonstrated that light could effectively treat the then common disfiguring disease, cutaneous mycobacterium tuberculosis. 

At the same time, light therapy and vitamin D were both being successfully used to treat tuberculosis up to the 1950s, when they were replaced with antibiotics. In the years following, the range of indications for phototherapy increased; by 1932, the American Medical Association listed 34 skin conditions for which UV therapy was recommended.

Advancements + Current Use

As the body of evidence supporting the benefits of phototherapy continued to grow, technological advancements paved the way for modern phototherapy. Developed in the 1980s, modern medical light therapy stemmed from the discovery of the action spectrum for psoriasis – ultimately leading to the invention of narrowband UVB.

Modern medical light therapy was developed in the 1980s with the discovery of the action spectrum for psoriasis, ultimately led to the development of narrowband UVB phototherapy.

This type of technology is delivered via a lightbox and is among the many different treatments available, also including psoralen and ultraviolet light A (PUVA) therapy, UVA-1, excimer laser therapy, and blue light photodynamic therapy.

Today, dermatologic experts use UV light therapy to shut down immune system activity to alleviate symptoms of skin conditions that are tied to overreactive immune systems. Currently, the role of UV light in the treatment of cutaneous disorders remains an active area of research, with novel technologies continuing to emerge as well as new dermatologic indications for its use.

UV Therapy Indications

Among the numerous indications for phototherapy, psoriasis is perhaps the most common, followed by eczema, mycosis fungoides, and vitiligo. At present, UVB therapy is recommended for the treatment of psoriasis, vitiligo, and other inflammatory skin disorders as is PUVA therapy. The innovative light therapy UVA-1 is not commonly available yet can be used to help treat scleroderma, morphea, and cutaneous graft-versus-host disease (GVHD). Excimer laser therapy is also used for the treatment of psoriasis and vitiligo, as well as dermatitis and mycosis fungoides as it is a highly precise technology that does not damage the skin. Furthermore, this technique requires fewer and shorter treatment than most other therapies. Finally, blue light photodynamic therapy can be used to treat acne vulgaris by reducing bacteria; it is also effective in the treatment of actinic keratoses when medication is applied to the skin and blue light is used to destroy precancerous skin lesions while leaving healthy skin untouched.

Risks of Phototherapy

As with all other treatment technologies, UV light therapy can also have adverse effects on the skin, including itchy skin, redness, burning, and making skin conditions temporarily worse. In addition, PUVA may cause nausea, burning, cataracts, headache, and fatigue. Similarly to sunlight, excessive exposure may cause premature aging and increase the risk of skin cancer. Patients at highest risk of complications include those allergic to sunlight, pregnant or nursing women, those with medical conditions that require sun avoidance, those with a history of skin cancer, and those with liver disease.

Despite its potential side effects, phototherapy has been deemed a relatively safe and extremely effective treatment method for a variety of cutaneous disorders. As further research efforts continue, the wide list of dermatologic indications may continue to expand and in the future, new light therapy technologies may emerge.