Photodynamic therapy (PDT)

Photodynamic therapy (PDT) is a treatment that involves light-sensitive medicine and a light source to destroy abnormal cells.

It can be used to treat some skin and eye conditions, as well as certain types of cancer.

On their own, the medicine and light source are harmless, but when the medicine is exposed to the light, it activates and causes a reaction that damages nearby cells.

This allows small abnormal areas of tissue to be treated without the need for surgery.

Uses for photodynamic therapy (PDT)

PDT can be used to treat abnormal cells in parts of the body that a light source can reach, such as the skin, eyes, mouth, food pipe (oesophagus) and lungs.

Conditions sometimes treated with PDT include:

PDT also shows promise in treating some other types of cancer, as well as warts, acne and extramammary Paget's disease (a pre-cancerous condition that affects skin around the genitals and anus).

What happens during photodynamic therapy (PDT)

There are 2 ways of having PDT:

Conventional PDT

Conventional PDT is done in 2 stages.

1) Preparation

2) Light treatment

Daylight PDT

Daylight PDT is used for some skin conditions. The medicine is a cream which is put on the affected area at a hospital or clinic, or sometimes at home. You'll then need to spend 2 hours outdoors in daylight to activate the medicine. You'll need to put on sunscreen while doing daylight PDT.

After photodynamic therapy (PDT)

Conventional PDT

If your skin was treated, the area will be covered by a dressing that should remain in place for about a day. Your care team will tell you exactly how long.

Try to avoid scratching or knocking the treated area, and keep it as dry as possible.

Once you're advised to remove the dressing, you can wash and bathe as normal, as long as you gently pat the treated area dry.

A follow-up appointment at the hospital or clinic will be arranged to assess whether the treatment has been effective and decide if it needs to be repeated.

It usually takes around 2 to 6 weeks for the area to heal completely, depending on which part of the body has been treated and how big the area is.

Daylight PDT

After daylight PDT, the medicine is wiped off and the area of skin that's been treated is covered for the rest of the day, to prevent swelling (inflammation).

If it's not possible to cover the area, you'll need to stay indoors or use a sunscreen (at least SPF 50) for the rest of the day after the treatment.

You'll have a follow-up appointment to see how well the treatment has worked and whether you need a 2nd treatment.

Risks and side effects of photodynamic therapy (PDT)

PDT is a very safe and effective treatment when it's used for conditions it's been officially approved (licensed) to treat. But the following side effects are common:

Other potential side effects depend on the area treated.

Talk to your doctors about the possible risks of PDT before having the treatment.

Page last reviewed: 31 March 2023
Next review due: 31 March 2026