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Phototherapy (Psoriasis)

As the name suggests, this psoriasis treatment uses natural or artificial ultraviolet light. Medically supervised phototherapy is the preferred method of phototherapy as it minimizes the risk of skin cancer by controlling the type and amount of ultraviolet light. Forms of light therapy include the medically supervised use of ultraviolet A (UVA) or ultraviolet B (UVB) light. In any form, light treatment is only effective if you get short-exposure – burns and skin damage can worsen psoriasis symptoms.

Phototherapy requires repeated exposure of the skin to ultraviolet light using one of several techniques. The procedure is done under medical supervision and may be advised when topicals alone are not effective.

Although the exact mechanism is not known, phototherapy may be both antiproliferative (i.e., inhibits cell growth) and immune modulatory (i.e., regulates or normalizes the immune system) in the way it works with respect to the treatment of psoriasis.

Phototherapy involves the use of ultraviolet light to treat psoriasis. There are multiple types of phototherapy available. It can vary from phototherapy delivered in a dermatologist’s office (narrow-band UVB phototherapy, broad-band UVB phototherapy, laser UVB phototherapy, PUVA phototherapy), to home phototherapy prescribed by a dermatologist. Your dermatologist can help determine which type of phototherapy may be most appropriate for your psoriasis and life situation.

To achieve success with phototherapy, consistency is key. Phototherapy can require a significant time commitment and thus may not be appropriate for everybody. Phototherapy sessions are typically prescribed 3 – 5 times per week, with improvement often being noticed in the first month.

Potential side effects of phototherapy include redness, itching, or skin pigmentary changes. Phototherapy may also increase one’s risk of skin cancer.

Psoralens UVA (PUVA) is not recommended during pregnancy.

UVB phototherapy is considered the safest treatment during pregnancy for widespread psoriasis not controlled with topical treatment.

Some medications can increase your sensitivity to light. If you are starting phototherapy or are on phototherapy and starting a new medication, be sure to ask your doctor or pharmacist if your medication can increase your sensitivity to light.

Types of Phototherapy

UVB, which is present in natural sunlight, penetrates the skin and slows the growth of affected skin cells. It involves exposing the skin to an artificial UVB light source for a set length of time on a regular schedule.

UVB light therapy can be narrow-band or broad-band treatment. Narrow-band is typically more effective than broad-band and may clear psoriasis faster and result in longer remissions. Both are administered using artificial light sources in a bed or booth, often located at a medical clinic or office.

UVB treatment is offered in different ways. This can include small units for localized areas such as the hands and feet, full-body units or hand-held units.

PUVA treatment comprises taking a light-sensitizing medication (psoralen) before exposure to UVA light. UVA light penetrates deeper into the skin than does UVB light, and psoralen makes the skin more responsive to UVA exposure. This more aggressive treatment is typically used for more severe cases of psoriasis. PUVA involves two or three treatments a week for a prescribed number of weeks. UVA is often administered in a stand-up booth at a medical clinic or office.

Excimer or pulsed-dye lasers can be used to treat psoriasis. The laser light is directed only at the affected areas of the skin. Excimer laser uses controlled UVB light whereas pulsed-dye lasers kill tiny blood vessels thought to contribute to psoriasis patches.

If you are considering a home phototherapy unit, your dermatologist can help determine which type of home phototherapy may be most appropriate for your psoriasis and life situation. It would also be important to discuss any potential sensitivities that you may have related to your own medical history and other possible medications or products that you use.

Some private insurance plans may cover home phototherapy units, though public plans generally do not. It is best to check what coverage you may have if you are considering a home phototherapy unit. Phototherapy equipment is currently listed as an allowable  Medical Expense Tax Credit under the Income Tax Act (see Canada Revenue Agency’s list of common medical expenses).

Last updated July 24, 2020.


This Site was designed for educational purposes only and not for the purpose of rendering medical advice. Individual variances in psoriasis cases require the consultation of a physician to make sound medical decisions. The information presented on this website is not intended to replace the counsel of your physician. It is important to see your doctor before altering anything in your treatment plan. The Canadian Psoriasis Network does not endorse any medications, products, equipment or treatments for psoriasis and psoriatic arthritis. Any of the information contained within the Canadian Psoriasis Network’s Site is not presented as a substitute for informed medical advice. Visitors to this site should not engage in self-diagnosis nor act on information contained in the Site without seeking specific advice on the particular matters which are of concern to them from qualified health professionals and advisors. Some of the information contained in the Site has been provided from external sources. While efforts have been made to ensure the accuracy, currency, and reliability of the content, the Canadian Psoriasis Network accepts no responsibility in that regard. Please refer to our Terms of Use for further details.

This resource was made possible through support from:

LEO Pharma