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Pronounced: Foto-ther-a-pee

En Español (Spanish Version)


In phototherapy, skin is exposed to an ultraviolet (UV) light source for a set amount of time to treat certain skin conditions. Ultraviolet lights are rays of light from the sun that are not visible. Phototherapy uses a man-made source of ultraviolet light for your treatment.

Types of phototherapy include:

  • Broad band UVB—effective light therapy treatment using UVB light (ultraviolet light, type B); cannot be used in areas where there are skin folds.
  • Narrow band UVB (nbUVB)—emits a narrower range of UVB wavelengths that can reach more specific areas, even skin folds.
  • PUVA—treatment involves taking or using a medication called psoralen, a light-sensitizing medication, before exposure to UVA, ultraviolet light A. Psoralen can be taken orally (as a pill through your mouth) or applied to the skin. The psoralen makes your skin more sensitive to the ultraviolet light.
  • Lasers—excimer laser emits an ultraviolet light that is even narrower than the Narrow Band UVB lights and can be directed at specific areas of the skin. Excimer laser is a relatively new procedure.

Parts of the Body Involved

Phototherapy can be applied to skin anywhere on the body.

Reasons for Procedure

Skin conditions that are treated with phototherapy include:

  • Psoriasis—a skin disorder that causes red, silvery, scaly patches on the skin caused by rapidly multiplying skin cells


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  • Dermatitis—skin conditions due to some sort of inflammation of the skin
  • Mycosis fugoides—(cutaneous T-cell lymphoma)—a type of lymphoma confined to the skin
  • Vitiligo—a skin disorder where normal skin pigment is lost due to destruction of pigment-producing cells by the immune system
  • Itching pruritus—result of liver or kidney disease

Risk Factors for Complications During the Procedure

  • Allergy to sunlight
  • Pregnancy or nursing
  • Medical conditions (such as skin cancer or lupus ) that require you to avoid the sun
  • History of skin cancer
  • Difficulty tolerating heat
  • Liver disease (phototherapy may increase medicine levels in the blood)

What to Expect

Prior to Procedure

You will be asked to remove any clothes covering the areas that need treatment. Areas that will not be treated should be covered and protected as much as possible to avoid exposure to the light.

  • Use sunscreen to protect your neck, lips, and backs of your hands
  • Protect your eyes by wearing special glasses or goggles that protect from ultraviolet light
  • Men need to cover their genitals and women should apply sunscreen to their nipples and areola (the colored area around the nipple)—unless these are the areas that are being treated

Make sure to inform your doctor about any medications that you are currently taking. Some medications, including over-the-counter medications, increase the risk of side effects from the phototherapy.


Anesthesia is not necesary during phototherapy.

Description of the Procedure

For Broad Band UVB, Narrow Band UVB, or PUVA treatment, you will be asked to stand in a treatment unit, called a light box, which is lined with ultraviolet lights. Sometimes smaller units for treating smaller areas of your skin may be used.

For treatment with an Excimer laser, your doctor will focus a beam of laser light directly on the affected area of your skin. Treatments last less than five minutes and approximately 5-10 treatments are necessary.

After Procedure

It is important to avoid natural sunlight when you are receiving ultraviolet light treatment.

  • Clothing and sunscreen are recommended to avoid being overexposed to ultraviolet light.
  • There is an even bigger risk of sunburn after PUVA treatment because psoralen makes the skin extremely sensitive to the sun.
  • To avoid cataracts after PUVA treatment, it is important to protect your eyes from sunlight exposure for the next 24 hours.
  • Your doctor should regularly examine your skin for skin cancer.
    • Ultraviolet light exposure from sunlight causes cancer, specifically skin cancer. Long term PUVA treatment can increase the risk of skin cancer, however, no studies have found a direct link from nbUVB phototherapy to skin cancer.
  • Antihistamines (a drug typically used to reduce allergic reactions) and other medications to ease the itching may be prescribed or recommended for use.

How Long Will It Take?

Treatment for skin conditions generally requires several treatments each week. It takes approximately 10 weeks to complete the full treatment.

  • Broadband therapy requires approximately 3-5 treatments each week.
  • Narrowband therapy requires fewer treatments (2-3 treatments) each week.
  • PUVA treatments generally require about 25 treatments over a 2-3 month period.
  • Laser treatments are usually given twice a week and fewer sessions are required to clear the skin.

The first treatment is usually very short, even a few seconds. Your phototherapy sessions will vary in length and will depend on your skin type and the strength of the light chosen by your doctor. Treatments are typically just a few minutes.

Treatments will continue until your skin is clear. Sometimes occasional maintenance treatments are necessary to keep the skin conditions under control. These maintenance phototherapy sessions usually can be done right in your doctor’s office or even with a home UV light unit.

Will It Hurt?

You may feel a warm sensation, similar to a mild sunburn, on your skin.

Possible Complications

The ultraviolet lights may negatively affect your skin in a number of ways, including:

  • Skin conditions could temporarily worsen
  • Itchy skin
  • Red skin due to exposure to the lights
  • Narrowband UVB can cause serious burning of the skin

PUVA treatment specifically may cause:

  • Nausea (if you took the psoralen pills)
  • Burning skin (if psoralen was applied to your skin)
  • Cataracts (lens of eye becomes cloudy, affecting vision)
  • Headache
  • Fatigue

If you have received a great number of phototherapy treatments within a short period of time, you may be at risk for: Premature aging of the skin, such as wrinkling and dryness. Age spots or freckles may appear

Average Hospital Stay

Phototherapy procedures do not require hospital stays, in fact they are usually done in your doctor’s office.


Phototherapy will help improve, or even clear, your skin of psoriasis lesions and certain types of dermatitis.

PUVA therapy offers long-lasting remission (period when the condition seems to have disappeared).

Call Your Doctor If Any of the Following Occurs

  • Blistering
  • Side effects you experienced due to the treatment continue or worsen
  • Symptoms of infection, including redness around the skin lesions, any discharge, painful lesions, or fever
  • Development of new or surprising symptoms


American Academy of Dermatology

National Psoriasis Foundation


Eczema Canada

Psoriasis & Phototherapy Clinic


Bili Lights. Medline Plus, National Library of Medicine – National Institutes of Health website. Available at: . Accessed August 23, 2005.

Gambichler T, Breuckmann F, Boms S, Altmeyer P, Kreuter A. Narrowband UVB phototherapy in skin conditions beyond psoriasis. J Am Acad Dermatol . 2005 Apr;52(4):660-70. Review.

Muekusch G, Pitman J, Smiljanic D. Photoresponsive diseases. Dermatol Nurs . 2007 Feb;19(1):43-7.

Phototherapy. American Academy of Dermatology website. Available at: . Accessed August 23, 2005.

Phototherapy: Lasers. National Psoriasis Foundation website. Available at: . Accessed August 23, 2005.

Phototherapy: PUVA. National Psoriasis Foundation website. Available at: . Accessed August 23, 2005.

Phototherapy: Tips for your protection and comfort. National Psoriasis Foundation website. Available at: . Accessed August 23, 2005.

Phototherapy: UVB phototherapy. National Psoriasis Foundation website. Available at: . Accessed August 23, 2005.

Last reviewed November 2007 by Ross Zeltser, MD

Please be aware that this information is provided to supplement the care provided by your physician. It is neither intended nor implied to be a substitute for professional medical advice. CALL YOUR HEALTHCARE PROVIDER IMMEDIATELY IF YOU THINK YOU MAY HAVE A MEDICAL EMERGENCY. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with any questions you may have regarding a medical condition.

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