About Your Phototherapy Procedure

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

The goal of phototherapy is to reduce the growth of your skin cells and to treat underlying skin inflammation. Phototherapy, also known as light therapy, does this by exposing your skin to ultraviolet (UV) light.

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

  • Psoriasis (raised, red, scaly patches on your skin)
  • Vitiligo (loss of color on patches of your skin)
  • Eczema, a condition that makes your skin red and itchy
  • Lichen planus (small bumps on your skin)
  • Cutaneous T-cell lymphoma (a type of lymphoma that appears as patches or scaly areas on your skin)
  • Itchy skin

How Phototherapy Works

Phototherapy uses UV light, which is also found in sunlight. There are 2 kinds of rays in UV light, 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’s 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 Photherapy

Your doctor will determine if phototherapy is safe for you. To do this, they will:

  • Do a total body skin exam by looking at all your skin. They will also ask about your reaction to sunlight.
  • Ask you about your personal 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.

Tell your doctor what medications you’re taking, including patches, creams, herbal supplements, and over-the-counter medications. Some medications, such as retinoids (including tretinoin), certain antibiotics, cancer medications, and others can make your skin more sensitive to UV light.

If you’re having PUVA light therapy, you will need to see your ophthalmologist (eye doctor) to have an eye exam before you begin.

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Planning Your Phototherapy

Phototherapy can be done in your home or in a doctor’s office.

Phototherapy in your doctor’s office

Memorial Sloan Kettering (MSK) does not currently do this procedure. If you’re having phototherapy in a doctor’s office, you will need to find a local dermatologist (skin doctor) that does this as an in-office procedure.

We can recommend a dermatologist(s), but if they do 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 www.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’re having phototherapy at home, you will need a home phototherapy machine. Your doctor’s office will send information to the company that will send you the machine and instructions for how to use it.

You can find more information about home phototherapy units and companies that supply them at: www.psoriasis.org/about-psoriasis/treatments/phototherapy/uvb/home-equipment

Depending on the type of home phototherapy machine 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 about _____ times for _______ weeks

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Giving Yourself Phototherapy at Home

  • Don’t put on lotion or moisturizer for 24 hours before each treatment.
  • For each treatment, you will need:
    • Protective goggles. You will get these from the company that supplies your phototherapy machine.
    • The home phototherapy machine.
  • If you’re only giving phototherapy to certain areas of your body, make sure all other areas are covered. You can cover them with clothing or sunscreen. This keeps your skin from getting burned. If you have any questions about covering your body, ask your doctor or nurse.
  • Wear protective goggles during every treatment, as instructed by your doctor or nurse. Wearing goggles will help prevent damage to your eyesight.
    • If your eyelids are the area being treated, you don’t need to wear the goggles but be sure to keep your eyes closed during your entire treatment.
  • The dose of phototherapy will be calibrated (pre-set) for you by the company that makes the machine.
  • Stay the correct distance from the unit throughout your treatment, as directed by your doctor or your home phototherapy machine instructions.
  • Expose your affected skin to the phototherapy light, as directed by your doctor.
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After Your Phototherapy

  • You may experience redness, itching, or a burning sensation after your phototherapy treatment. 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 your skin
  • One or more new lesions (skin growths or patches that don’t look like the skin around them) on the affected area after your treatment
  • Flu-like symptoms, such as:
    • Headaches or body aches
    • Fatigue
    • Nausea or vomiting
    • Diarrhea (loose or watery bowel movements)
    • Cough
    • Sore throat
    • Runny or stuffy nose
  • Any open areas on your skin, including cuts, tears, blisters, burns, or ulcers
  • Redness on the skin that was treated that lasts for more than 24 hours
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American Academy of Dermatology

National Psoriasis Foundation

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