Photodynamic Therapy

Light-activated treatment for sun-damaged skin.

Photodynamic therapy (PDT) uses a photosensitizing medication followed by exposure to a specific light source to help treat certain precancerous or sun-damaged skin lesions.

An overhead shot of a person inside a photodynamic therapy machine with protective glasses on. The picture is tinted purple.

What is photodynamic therapy (PDT)?

Photodynamic therapy (PDT) uses a photosensitizing medication that is activated by a specific light source. When the medication is exposed to the light, it helps treat certain precancerous or localized skin lesions. PDT is most commonly used for patients with sun-damaged skin and actinic keratoses.

In addition to its medical use, PDT may also improve the appearance of sun-damaged skin by helping it look clearer and smoother, though individual results vary.

Photodynamic therapy may be used for:

Actinic keratoses
Superficial basal cell carcinoma
Squamous cell carcinoma in situ (Bowen’s disease)

Dr Ben standing in the right side of the picture in scrubs and a mask beside a person sitting in a photodynamic therapy machine with DUSA written down the side.

How photodynamic therapy works.

A photosensitizing medication is applied to the area being treated and allowed time to absorb into the skin. After the appropriate interval, a blue or red medical light is directed at the area to activate the medication. This light activation triggers a reaction that helps target the abnormal or sun-damaged cells being treated.

The period between applying the medication and activating it with light is called the drug-to-light interval. The length of this interval can range from immediately to several hours, depending on the specific photosensitizing agent being used.