Light Therapy (Phototherapy) for Psoriasis Treatment

Reviewed by: HU Medical Review Board | Last reviewed: January 2024

Phototherapy is a type of treatment for people with psoriasis. It is also called light therapy. Light therapy involves using a machine or device to expose skin to ultraviolet (UV) light. This exposure is done for specific amounts of time on a planned schedule.1,2

How does light therapy work?

The specific way light therapy works depends on the type that is used. Light therapy can help reduce inflammation and immune response, which are causes of psoriasis. Light therapy can help kill or slow the growth of extra skin cells that people with psoriasis overproduce. It can also reduce itching.3,4

Examples of light therapy

There are several different types of light therapy for psoriasis. Your doctor will determine which option is best for you based on where your psoriasis is and how severe it is. Light therapy options include:1-3

  • Ultraviolet light B (UVB)
  • Psoralen + UVA (PUVA) bath, cream, or pills
  • Sunlight

UVB involves exposing the skin to an artificial UVB light source. UVB is the most common light therapy for psoriasis. There are different types of UVB therapy available, including narrowband and broadband. Broadband UVB may be more effective for psoriasis.1,3

The excimer laser is also approved by the Food and Drug Administration (FDA) for psoriasis. This laser uses a high-intensity beam of UVB and usually takes fewer sessions to work.1,3

UVA alone does not help psoriasis. But UVA with drugs called psoralens can treat psoriasis. Psoralen makes your skin more sensitive to UV light. This process is called psoralen UVA (PUVA). You can use psoralens as a pill, cream, or in a bath. After this, you receive UVA light exposure. If you are using psoralens, avoid sunlight exposure.1,2

Natural sunlight gives off UVB and UVA light. However, natural sunlight is not as effective as targeted light therapy. Protect your healthy skin with sunscreen or clothing if you use sunlight on your psoriasis. It is important to note that sunburn can make psoriasis worse.1,2

Do not use tanning beds as a substitute for light therapy or natural sunlight. Tanning beds mostly give off UVA light. UVA light alone is not effective for psoriasis. Indoor tanning also greatly increases your risk for skin cancer.1,2

What are the possible side effects of light therapy?

Side effects can vary depending on the specific treatment you receive. Possible side effects include:1,2

  • Sunburn-like skin irritation, such as red or tender skin
  • Stinging or burning feeling
  • Dark spots on skin
  • Blisters or burns on skin

Long-term effects can include freckles or early signs of skin aging, like wrinkles or age spots. There is also an increased risk of skin cancer. Dermatologists can help manage these risks. However, light therapy may not be recommended for some people including:1,2

  • People with skin cancer
  • People at risk of developing skin cancer
  • Anyone with sensitivities to UV light

These are not all the possible side effects of light therapy. Talk to your doctor about what to expect when using light therapy. You also should call your doctor if you have any changes that concern you when using light therapy.

Other things to know

Light therapy is typically given at a hospital or treatment center. However, there are some at-home options. You will typically need 2 to 3 treatments per week. Attending the prescribed number of treatments is important for overall success.1,2

Before beginning treatment for psoriasis, tell your doctor about all your health conditions and any other drugs, vitamins, or supplements you take. This includes over-the-counter drugs.

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