About Your Phototherapy Procedure

Time to Read: About 4 minutes

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 putting ultraviolet (UV) light on your skin.

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. 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 if more than 5% of your skin is affected.

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.

Before Your Phototherapy

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’re pregnant or if you’re breastfeeding.

Tell your doctor what medications you’re taking, including patches, creams, herbal supplements, and over-the-counter medications (medications you get without a prescription). 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.

Planning Your Phototherapy

Phototherapy is done in your local dermatologist’s (skin doctor) office but if you will need long-term therapy, you can talk to your local dermatologist about doing phototherapy from your home.


Phototherapy in your dermatologist’s office

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

We can recommend a dermatologist(s), but if they don’t 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 healthcare provider 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.

Give your MSK dermatologist your local dermatologist’s information by sending them a message on the portal or by calling their office.

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.

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 getting 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 healthcare provider.
  • Wear protective goggles during every treatment, as instructed by your healthcare provider. 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.

After Your Phototherapy

  • You may have 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 your skin starts getting better. 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.

When to Call Your Healthcare Provider

Call your healthcare provider if you have the following:

  • A fever 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 (feeling more tired or weak than usual)
    • Nausea (feeling like you’re going to throw up)
    • Vomiting (throwing up)
    • 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


American Academy of Dermatology


National Psoriasis Foundation

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Last Updated

Tuesday, March 3, 2020