About Your Phototherapy Procedure

This information explains what phototherapy is and what to expect before, during, and after your procedure. 

Phototherapy, also known as light therapy, is a treatment that exposes you to ultraviolet (UV) light. The goal of phototherapy is to reduce the growth of your skin cells and to treat underlying skin inflammation.

Phototherapy can be used to treat several skin conditions, including:

  • Psoriasis (raised, red, scaly patches on the skin)
  • Vitiligo (loss of color on patches of the skin)
  • Atopic dermatitis (also known as eczema, a condition that makes the skin red and itchy)
  • Lichen planus (small bumps on the skin or mucous membranes)
  • Cutaneous T-cell lymphoma (a type of lymphoma that appears as patches or plaques on the skin)
  • Generalized pruritus (itchy skin)

How Phototherapy Works

Phototherapy uses UV light, which is also found in sunlight. There are 2 kinds of rays, ultraviolet A rays (UVA) and ultraviolet B rays (UVB). Phototherapy can also be used in combination with other topical (applied on the skin) therapies.

Phototherapy can be given to a specific area of your body or to your entire body. It is given to your entire body if more than 5% of your skin is covered with the rash or skin condition.

There are 2 main types of phototherapy:

  • Ultraviolet B (UVB)
    • There are 2 types of UVB phototherapy, including broadband and narrowband (NB-UVB). The difference is that NB-UVB gives off a shorter wavelength of UV light.
  • Psoralen-UV-A (PUVA)
    • This type of therapy uses UVA light and an oral (by mouth) medication called psoralen that makes your skin more sensitive to light. 
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Before Your Procedure

  • Tell your doctor what medications you are taking, including patches, creams, herbal supplements, and over-the-counter medications.
    • Some medications, such as retinoids (tretinoin), certain antibiotics, anticancer medications, and others can make your skin more sensitive to UV light.
  • Your doctor will determine if phototherapy is safe for you. To do this, he or she will:
    • Do a total body skin exam by looking at all your skin. He or she will also ask about your reaction to sunlight.
    • Ask you about your personal history and family history of skin cancer and photosensitizing disorders (disorders that make your skin more sensitive to the sun).
    • Ask if you are pregnant or if you are breastfeeding.

If your doctor recommends phototherapy, it can be done in your home or in your doctor’s office. If you are having PUVA light therapy, you will need to see your ophthalmologist (eye doctor) to have an eye exam before you begin.

Phototherapy in your doctor’s office

If you are having phototherapy in a doctor’s office, you will need to find a local dermatologist that does this as an in-office procedure. Memorial Sloan Kettering (MSK) does not currently do this procedure. We can recommend a dermatologist(s), but if he or she does not accept your insurance, you can find a dermatologist at: www.psoriasis.org/health-care-providers/physicians-directory or www.aad.org/for-the-public. Your nurse can also give you a list of dermatologists that do phototherapy in their office from the aad.org website.

Your dermatologist will explain what you need to do and how long you will receive your phototherapy. 

Phototherapy at home

If you are having phototherapy at home, you will need a home phototherapy unit.  Your information will be faxed to the company that will provide you with the machine and instructions for use. You can find more information about the home phototherapy unit and companies that supply them at: www.psoriasis.org/about-psoriasis/treatments/phototherapy/uvb/home-equipment

Depending on the type of home phototherapy unit you use, you will need to:

  • Fill out a home phototherapy patient order form and any other needed forms.  Your doctor who ordered phototherapy for you will give you these.
  • Have your doctor’s prescription that includes the type of therapy and the dose.

You will receive phototherapy at home approximately_____ times for _______ weeks

During Your Procedure (Phototherapy at Home)

  • Do not put on lotion or moisturizer for 24 hours before your procedure.
  • For each treatment, you will need:
    • Protective eyewear. These will be provided by the company that supplies your phototherapy machine.
    • The home phototherapy unit that your doctor prescribed.
  • The dose of phototherapy will be calibrated for you by the company that makes the machine.
  • Wear protective eyewear and cover unaffected areas in the exact same place during every treatment, as instructed by your doctor or nurse. This will help prevent burns and damage to your eyesight.
  • Stay the correct distance from the unit throughout your treatment, as directed by your doctor or your home phototherapy unit instructions.
  • Expose your affected skin to the phototherapy light.
  • Do your treatment  as directed by your doctor.
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After Your Procedure

  • You may experience redness, itching, and a burning sensation with the home phototherapy unit. These are all normal side effects of this therapy.
  • Phototherapy can dry out your skin. Moisturize your skin with a fragrance-free moisturizer, such as Aquaphor® or Cetaphil®, at least once a day.
  • It may take 6 to 8 treatments before you start to notice any improvement in your skin. For some people, it may take 2 months to see improvement. 


  • You may need to follow-up with your dermatologist who is managing your skin condition, your ophthalmologist, and your doctor at MSK.
  • Ask your doctors when you should schedule these appointments.
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Call Your Doctor or Nurse if You Have:

  •  A temperature of 100.4°F (38°C) or higher
  • Chills
  • Blistering, cracking, drainage, or a rash on the skin
  • New lesion(s) (any skin growths or patches that do not look like the surrounding skin) developing on the affected area after your treatment
  • Flu-like symptoms such as:
    • Headaches or body aches
    • Fatigue
    • Nausea or vomiting
    • Diarrhea
    • Cough
    • Sore throat
    • Runny or stuffy nose
  • Any open areas on your skin, including cuts, tears, blisters, burns, or ulcers
  • Redness lasting for more than 24 hours on the skin that was treated
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