by Safer DA


Phototherapy uses lightwaves to treat certain skin conditions. The skin is exposed to an ultraviolet (UVB or UVA) light for a set amount of time. Phototherapy uses a man-made source of UV light. UV light also comes from the sun. UVA treatment is usually combined with a medication called psoralen, the procedure is known as psoralen UVA (PUVA). The choice of treatment may depend on the condition being treated.

This topic does not cover phototherapy for jaundice in babies.

Reasons for Procedure

UV light shuts down immune system cells in the skin. It can help in skin conditions that are caused by an overreaction of the immune system. Skin conditions that are treated with phototherapy include:

  • Psoriasis —a skin disorder that causes red, silvery, scaly patches on the skin
  • Atopic dermatitis —eczema, an itchy, red skin condition, or dermatitis due to allergies
  • 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
  • Lichen planus —an inflammatory skin condition
  • Alopecia areata —areas of baldness
  • Pityriasis rosea —skin rash most commonly affecting children and young adults
  • A rare form of Crigler-Najjar syndrome
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Possible Complications

The UV 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
  • Burning of the skin
  • Ocular toxicity (photokeratitis)

PUVA treatment may also cause:

  • Nausea and appetite loss
  • Burning skin
  • Headache
  • Fatigue

If you have received a great number of phototherapy treatments, you may be at risk for:

  • Cataracts —lens of eye becomes cloudy, affecting vision
  • Premature aging of the skin, such as wrinkling and dryness
  • Age spots or freckles
  • Skin cancer

Factors that may increase the risk of complications include:

  • Allergy to sunlight
  • Pregnancy or nursing
  • Medical conditions, such as skin cancer or systemic lupus erythematosus , that require you to avoid the sun
  • History of skin cancer
  • Liver disease—phototherapy may increase medication levels in the blood

What to Expect

Prior to Procedure

You will be asked to remove any clothes that cover the skin being treated. Areas that do not need treatment should be covered and protected as much as possible. Some safety steps include:

  • Sunscreen to protect your neck, lips, and the backs of your hands
  • Special glasses or goggles to protect your eyes from UV light
  • Cover for genitals in men
  • Sunscreen for nipples and areola in women

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

Description of the Procedure

Types of phototherapy include:

  • Broad band UVB—Uses UV light, type B. It cannot be used in areas where there are skin folds.
  • Narrow band UVB (nbUVB)—Uses a narrower range of UVB wavelengths. It can reach more specific areas, even skin folds.
  • PUVA—This UVA light treatment includes a medication called psoralen that is taken before treatment. It makes your skin more sensitive to the light. Psoralen can be taken as a pill or applied to the skin.
  • Lasers—An excimer laser emits a UV light. It can be directed at specific areas of the skin.

Treatment over a large area may be treated in a treatment unit. You can stand in this unit during treatment. Smaller areas may be treated with smaller units. A laser treatment will use a laser light that is focused on the specific area.

How Long Will It Take?

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

Generally, several treatments are required each week. The length of treatment will depend on the type of phototherapy:

  • Broad band therapy requires approximately 3-5 treatments each week.
  • Narrow band therapy requires 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.

Treatments will continue until your skin is clear. Sometimes, occasional maintenance treatments are needed. The maintenance sessions can usually be done in your doctor’s office or with a home UV light unit.

Will It Hurt?

You may feel a warm sensation on your skin, similar to a mild sunburn. Your doctor can recommend medication if you have discomfort after treatment.

Post-procedure Care

It is important to avoid natural sunlight when you are receiving UV light treatment:

  • Clothing and sunscreen should be used when outdoors. They will help you avoid overexposure to UV light.
  • There is an increased risk of sunburn after PUVA treatment. This is due to increased sensitivity from the psoralen.
  • It is important to protect your eyes from sunlight exposure for the next 24 hours. This will help you to avoid cataracts after PUVA treatment.
  • Antihistamines and other medication may be given to ease the itching.

Your doctor should regularly examine your skin for skin cancer. UV light exposure from sunlight causes skin cancer. Long-term PUVA treatment can also increase the risk of skin cancer. No studies have found a direct link from nbUVB phototherapy to skin cancer.

Call Your Doctor

Contact your doctor if your recovery is not progressing as expected or you develop complications, such as:

  • Signs of infection, including fever and chills
  • Redness around the skin lesions or any discharge
  • Severe skin burning, pain, or blistering
  • Side effects you experienced due to the treatment continue or worsen
  • New or unexpected symptoms

If you think you have an emergency, call for medical help right away.


American Academy of Dermatology 

National Psoriasis Foundation 


Eczema Canada 

Health Canada 


American Academy of Dermatology’s newest guidelines for the management of atopic dermatitis focus on treatments. American Academy of Dermatology website. Available at: Accessed December 18, 2017.

Indications for phototherapy. Derm Net AZ website. Available at: Updated November 10, 2014. Accessed December 18, 2017.

Phototherapy. National Psoriasis Foundation website. Available at: Accessed December 18, 2017.

Psoriasis. EBSCO DynaMed Plus website. Available at:  . Updated December 4, 2017. Accessed December 18, 2017.

Psoriasis: General principles for phototherapy. American Academy of Dermatology website. Available at: Accessed December 18, 2017.

UVA photo(chemo) therapy. Derm Net AZ website. Available at: Accessed December 18, 2017.

UVB phototherapy. Derm Net AZ website. Available at: Accessed December 18, 2017.

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