Skin cancer: What to expect from photodynamic therapy

Written by: Dr Raj Mallipeddi
Published: | Updated: 06/05/2023
Edited by: Laura Burgess

Photodynamic therapy is a procedure that uses a light source alongside chemicals, known as photosensitisers, as a treatment for some skin and eye conditions and some types of cancer.

Skin cancer, such as basal cell carcinoma, is the most common type of condition that is treated using photodynamic therapy techniques. If you have recently been told that photodynamic therapy is the correct procedure for your case, you may be wondering what happens and whether it will be a painful experience or not.

Here, one of our top London dermatologists, Dr Raj Mallipeddi, explains what you can expect both during and after photodynamic therapy.



When are patients referred to photodynamic therapy treatment?


If patients have been diagnosed with superficial skin cancers or pre-cancers, they might require photodynamic therapy. These conditions include superficial basal cell carcinoma, Bowen's disease (squamous cell carcinoma in situ) and actinic keratoses.

How do patients prepare for photodynamic therapy?


There is usually no specific preparation by patients beforehand.

What happens during a photodynamic therapy session? Does it hurt?


Conventional photodynamic therapy involves removing any scale or crust if necessary, and then applying a cream which is sensitive to light (photosensitiser). This is covered for around three hours so that it is absorbed by the area requiring treatment.

The dressing is then removed and a special light is shone on the area(s) after wiping away the cream. The exposure to the light is often less than 10 minutes, but allows for a chemical reaction between the light and the absorbed cream to destroy abnormal cells

Once completed, a dressing is applied for two days to prevent further light exposure. The dressing is then removed and the area is washed as usual, along with regular moisturising for the following week. It can be uncomfortable during treatment, although cold air is used to reduce the pain.  

Is there an alternative photodynamic therapy procedure?


Daylight photodynamic therapy is an alternative method for certain cases. This involves applying sunscreen on the area to be treated after removing any scale or crust, and then applying the photosensitising cream. Within 30 minutes, the area should be exposed to daylight for two hours continuously.

This is only suitable during the time of the year when there is sufficient daylight, which is usually April to October in the UK. After the two-hour exposure, the cream is wiped away and a dressing may be applied for the rest of the day to avoid further sun exposure. Then, as with conventional photodynamic therapy, the treated areas are moisturised regularly for one week to minimise scabbing. 

How many sessions are usually needed? 


For superficial basal cell carcinoma, two sessions are performed one to two weeks apart. For actinic keratoses, one session may suffice.

Dr Raj Mallipeddi is a highly-experienced dermatological surgeon who specialises in the latest treatments in skin cancer and cosmetic dermatology. Do not hesitate to book an appointment with him via his Top Doctors profile today.

By Dr Raj Mallipeddi

Dr Raj Mallipeddi is an award-winning consultant dermatological surgeon based in London who specialises in skin cancer, cosmetic dermatology and surgical dermatology alongside Mohs surgery, laser surgery, and photodynamic surgery. He practices privately for HCA Sydney Street Outpatient Centre, Dermatological Surgery, Laser Unit at Guy's Hospital Cancer Centre, and Bupa Cromwell Hospital. He also works for the Guy's and St Thomas' NHS Foundation Trust.

Dr Mallipeddi is well respected in the dermatology and skin cancer field, working in lead roles at top centres in the capital. He is the lead clinician for dermatological surgery and the laser unit at St John's Institute of Dermatology at Guy's Hospital Cancer Centre and was the lead consultant for skin cancer for his NHS trust, seeing referrals from all over the UK. Dr Mallipeddi studied at Imperial College in London where he was awarded an MBBS in 1997. During this time, he also completed an intercalated BSc (Hons) degree in psychology at University College London in 1994. Subsequently, he obtained a Doctor of Medicine higher research degree studying squamous cell carcinoma at King's College London from 2001 to 2003.

Dr Mallipeddi has been professionally recognised as well as by patients. He has been awarded the St John's Dermatological Society registrar prize, the Wooden Curette Award from the British Society for Dermatological Society and named by Marquis (American publisher of directories) as the Who's Who in Healthcare 2009-10. As well as being a highly-qualified professional, Dr Mallipeddi lectures nationally and internationally. He is also heavily involved in medical education as the national curriculum lead for Mohs and Advanced Dermatological Surgery and he has written the "practical procedures" chapter in the "ABC of Dermatology" book. 

He is also widely published, and a pioneer in his field for being one of the only UK doctors who has completed advanced training in Mohs micrographic surgery as certified by the American College of Mohs Surgery. He serves on numerous boards including chair of the UK Mohs micrographic service standards committee and was the past President of the British Society for Dermatological Surgery (2015-2017). Furthermore, he is past president of the St John's Dermatological Society (2021-2022). 

He was a member of the British Association of Dermatologists' (BAD) guideline committees for basal cell carcinoma, squamous cell carcinoma and photodynamic therapy and has helped to develop important national guidelines.

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