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Phototherapy for Skin Conditions: How It Works

A cartoon of a woman doing phototherapy for skin conditions.

If you have a chronic skin condition, your dermatologist may recommend phototherapy treatments with ultraviolet (UV) light or LED light. Please continue reading to find out how phototherapy (light) treatment works to treat skin disorders.

What is phototherapy?

Phototherapy is a treatment that uses light to treat skin conditions. It can be done under medical supervision in a doctor’s office. You can also do phototherapy at home in some cases. 

The treatment is performed using artificial UV light (ultraviolet light), other types of artificial light like LED light or fluorescent light bulbs, or natural sunlight exposure. The most common type of light therapy is UVA and UVB phototherapy. 

What skin conditions can be treated with light therapy?

Phototherapy can be used to treat itchy skin, newborn jaundice, inflammatory skin disorders like eczema, psoriasis, morphea (localized scleroderma), skin vitiligo (a skin disorder in which patches of milky white skin develop due to loss of pigment), and mycosis fungoides (a type of blood cancer called cutaneous T cell lymphoma). In addition to skin disorders, phototherapy treatments are also used to treat seasonal affective disorder (a type of depression related to changes in season).

What type of phototherapy will I need?

The choice of light therapy depends on your skin disorder. Ultraviolet rays are a part of the electromagnetic spectrum. Sunlight contains ultraviolet (UV) light, which helps the skin produce vitamin D. But too much ultraviolet light is harmful and can cause sunburns, premature aging, and skin cancer. 

There are different types of UV light used in light therapy. Ultraviolet B light has a medium wavelength. Phototherapy treatment with UVB light is used to treat skin conditions that affect the upper layers of the skin. Narrowband UVB light is a specific range of wavelengths (308-312 nm) that are most effective in treating skin diseases. However, prolonged UVB therapy can cause sunburn.

UVA light has a longer wavelength and penetrates deeper into the skin. Therefore, UVA light or PUVA treatment is used for conditions that affect the inner layers of the skin. Overexposure to UVA light can cause wrinkles and premature skin aging.

Other types of light therapy include LED light therapy, which does not contain ultraviolet radiation (UV rays). Blue LED light treatments are used to treat jaundice. Red LED light phototherapy is used to treat skin issues like wrinkles, acne, redness, and scars.

Photochemotherapy is a unique treatment in which a photosensitizing medication called psoralen is used along with ultraviolet light. The medicine helps to sensitize the skin to radiation such that a lower dose of radiation has a beneficial effect. PUVA treatments (psoralen plus UVA) are used for psoriasis and other photoresponsive skin conditions like mycosis fungoides and vitiligo

Photodynamic therapy is a two-stage treatment that utilizes topical medications (photosensitizing drugs) and specific wavelengths of light to treat acne, psoriasis, and certain types of cancers.

How does phototherapy treat skin conditions like newborn jaundice?

Light therapy is commonly used to treat newborn jaundice, a condition in which the baby’s skin and eyes turn yellow due to high levels of bilirubin. Left untreated, it can cause kernicterus (permanent brain damage), hearing loss, and cerebral palsy. 

Blue LED light therapy converts bilirubin to water-soluble byproducts that can be excreted without hepatic metabolism. These are non-toxic and do not cross the blood-brain barrier.

How does phototherapy work for psoriasis? 

Psoriasis is a chronic skin disorder with no cure. People with this disorder develop plaques (skin lesions) consisting of dry, itchy, scaly patches

The National Psoriasis Foundation says regular phototherapy sessions with UVB rays or Excimer laser light (UVB treatment with a high-intensity beam) is an effective psoriasis treatment. It can help to keep psoriasis plaques under control and reduce the severity of psoriasis symptoms. Phototherapy treatments work by causing apoptosis (programmed death of skin cells in psoriatic lesions).

How does phototherapy work for atopic dermatitis (eczema)?

This is a skin disorder characterized by dry, itchy, inflamed skin. It is common in young children but can occur at any age. A phototherapy procedure using narrowband UVB light or UVA1 can be an effective treatment for atopic dermatitis. Phototherapy works by targeting inflammatory and immune system cells and reducing the formation of inflammatory substances such as cytokines. Phototherapy also has an antimicrobial effect on the skin. 

What happens during a phototherapy procedure?

You will be asked to wear protective eyewear before a phototherapy treatment. Your healthcare provider may ask you to apply sunscreen on the treatment area, use a photosensitizing medication such as psoralen, or take medication by mouth prior to your light therapy session. 

The procedure may be done with you standing up in a phototherapy unit. If you are having laser treatment, you may be asked to lie down on a bed. 

The length of the procedure is only a few seconds to a few minutes. Phototherapy is painless, and you can expect to be reasonably comfortable. 

The number of phototherapy sessions you will need depends on your skin condition. However, in general, multiple phototherapy sessions (anywhere from 6 to 25) are required to get results. Your healthcare provider will discuss the treatment plan with you.

What happens to skin after phototherapy?

Skin is more sensitive to sunlight after phototherapy. Therefore, your provider will ask you to avoid unnecessary sun exposure or the use of tanning beds in tanning salons. You should use sunscreen and wear sunglasses when outdoors. A moisturizer can help prevent dry skin after light therapy.

Does light therapy increase the risk of skin cancer?

Prolonged use of UVA light can increase your risk of skin cancer. Prolonged use of UVB light can lead to wrinkles and premature aging. 

What are the side effects of phototherapy?

Side effects of phototherapy treatments include skin dryness, redness, a burning sensation, and blisters (similar to a sunburn), especially in the first 24 hours. You may also experience nausea if you are given photosensitizing drugs along with the UV light.

Who can get phototherapy?

Phototherapy is safe for infants, children, and adults. It can be done on every skin type. 

Who should not get phototherapy?

You may not be a candidate for UVA phototherapy if you have a personal or family history of skin cancer. Also, your doctor may recommend against UV light therapy if you are pregnant or nursing or have certain health conditions such as sun allergy, liver disease, lupus, xeroderma pigmentosa (a genetic condition associated with an increased risk of sun damage), or if you are taking certain medications that increase your skin’s sensitivity to light.



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