What is PDT?

It feels good to lounge in the sunshine, but over the years, too much time outdoors can put you at risk of wrinkles, age spots, scaly patches known as actinic keratosis, and skin cancer. In this month’s journal I explain the benefits of daylight photodynamic therapy (PDT), a light-based treatment for pre-cancerous, sun-damaged skin.

Daylight PDT involves applying a special cream to the affected area of your skin followed by exposure to sunlight for several hours to destroy damaged skin cells, leaving nearby healthy cells unchanged.

Daylight PDT can be used to treat general photodamage and actinic (solar) keratosis. It can also be used for acne.

How does photodynamic therapy work?

Photodynamic therapy involves the application of a light-sensitive (photosensitiser) cream onto the affected area of your skin. When exposed to specific wavelengths of light, the photosensitiser is activated.  This affects the oxygen molecules within the damaged skin and ultimately causes destruction of abnormal skin cells.

What can you expect at your daylight PDT appointment?

Chemical sunscreen will be applied to the area to be treated and any other areas which will be exposed to sunlight during the treatment. This will be left for around twenty minutes to absorb into your skin. The next step is to prepare your skin by degreasing and removing any overlying crusting. The photosensitising cream will be applied to the area of treatment and left uncovered.

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You will then be asked to sit outside in the natural sunlight for two continuous hours. This activates the cream which begins to destroy the damaged cells. There is enough daylight for the treatment to work even on a dull or cloudy day.

After two hours, the treated area is cleansed at home. Sun exposure should be avoided for 48 hours.

What happens after your daylight PDT appointment?

You’ll be given detailed instructions on how to care for your skin afterwards, but you can shower and bathe as normal. Some clients find that the area may weep a little and form a crust, this is normal.

What are the potential side effects of daylight photodynamic therapy?

Short term:

  • Mild stinging or tingling during treatment
  • Inflammation, blistering and ulceration, the treated area may become swollen or puffy. This is normal and should be resolved in a few days
  • Infection, there is a small risk of infection due to the broken skin barrier.  This can be easily treated

Long term:

  • There is a very small risk of scarring, but this is rare, usually, skin texture is improved
  • Colour change, treated areas may become slightly lighter or
  • The condition may come back again. Further PDT or an alternative treatment may be needed.

Finally, be sun aware!

After PDT patients should adopt a regime of sun protection immediately post-treatment and for the long term. This should include avoiding the sun during peak hours, wearing protective clothing and using SPF 45+ sunscreens on all exposed parts of your skin.