Photodynamic therapy (PDT)

Also known as

Conditions treated

How it’s performed

A nurse or therapist prepares the area to be treated by cleaning it with alcohol or acetone, and sometimes by microneedling (i.e. making many small punctures in the skin using an electronic device, to allow the treatment cream to penetrate the skin better. They then apply a thick layer of aminolevulinic acid (ALA) cream to the area to be treated. The cream is covered with a dressing or plastic film and left on the skin for 1-3 hours. After this period, the ALA cream is cleaned off the surface of the skin. ALA which has penetrated into skin cancer or sun-damaged cells is then activated by light. A combination of red low level light for approximately 15 minutes and/or intense pulsed light may be used. Following this, the nurse or dermal therapist will apply sunscreen and/or a cooling gel to the treated area. They may also cover it with a dressing, which should be left in place for 2-3 days.

The skin should be prepared for treatment by clearing any scale or crusts. Your doctor may prescribe or recommend a cream or ointment for this. If so, use it daily for 1-2 weeks. For 2-3 days before treatment, avoid skin irritants such as tretinoin and other retinoids, vitamin C and other acids. If possible, do not take any medications that increase skin sensitivity to light, e.g. doxycycline. (You should confirm with your prescribing doctor that it is safe to do tis.) On the day of treatment, make sure your skin is clean and do not wear any make-up.

Side effects and complications

Some people find the light treatment painful. This can be treated with a cold compress or spray or medication administered at the time of treatment. It is unusual for strong pain to persist after treatment, but the skin may sting or itch and there is often redness or peeling for several days. Serious complications of PDT are rare.

Follow-up

Return to the clinic after about 1 month so that the doctor can examine the skin and determine whether PDT has successfully treated your solar keratoses or skin cancer. In some cases, further treatment may be required.

Aftercare

Contraindications

Porphyria, systemic lupus erythematosis, rashes made worse by light, allergy to aminolevulinic acid.

Pregnancy