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 skin inflammation (swelling). Phototherapy, also known as light therapy, does this by putting ultraviolet (UV) light on your skin.

Phototherapy is used to treat a few skin conditions, including:

  • Psoriasis (suh-rahy-uh-sis), which is raised, red, scaly patches on your skin
  • Vitiligo (vit-i-li-goh), which is loss of color on patches of your skin
  • Eczema (ek-suh-muh), which is a condition that makes your skin red and itchy)
  • Lichen planus (LY-ken PLAY-nes), which is 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  along with other topical (applied on the skin) therapies.

Phototherapy can be used on one area of your body. It also can be used on all of your 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). 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) medicine called psoralen that makes your skin more sensitive to light.

Before your phototherapy

Your doctor will decide 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. These are conditions that make your skin more sensitive to the sun.
  • Ask if you’re pregnant or breastfeeding.

Tell your doctor what medicine you’re taking. This includes patches, creams, herbal supplements, and over-the-counter medicine you get without a prescription. Some medicines can make your skin more sensitive to UV light. Examples are retinoids (including tretinoin), and some antibiotics and cancer medicines. 

If you’re having PUVA light therapy, you must visit your ophthalmologist (eye doctor) to have an eye exam before you start.

Planning your phototherapy

Phototherapy is done in your local dermatologist’s (skin doctor) office.

If you need long-term therapy, you can talk to your local dermatologist about doing phototherapy from your home.


Phototherapy in your dermatologist’s office

MSK does not offer this procedure. If you’re having phototherapy in a doctor’s office, you must find a local dermatologist who does this procedure.

We can recommend a dermatologist. If they do not accept your health 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 for how long you will get phototherapy.

Give your MSK dermatologist your local dermatologist’s information. You can send them a message through our patient portal, MyMSK, or call their office.

Phototherapy at home

If you’re having phototherapy at home, you’ll need a home phototherapy machine. Your doctor’s office will send information to the company that will send you the machine. You will also get instructions about 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. You will get these forms from the doctor who ordered phototherapy for you.
  • Your doctor’s prescription, which includes the type of therapy and the dose.

You will have phototherapy at home about _____ times for _______ weeks.

Giving yourself phototherapy at home

  • Do not put on lotion or moisturizer for 24 hours (1 day) 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 some parts of your body, make sure you cover all other areas. 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 harm to your eyesight.
    • If your eyelids are the area being treated, you do not need to wear the goggles. 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 during your treatment. Your doctor or your home phototherapy machine instructions will give you the correct distance.
  • 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. 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. You may also need to follow-up with 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 any of 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 on the affected area after your treatment. These are skin growths or patches that do not look like the skin around them.
  • 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

Last Updated

Thursday, February 29, 2024

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