What should you know about topical photodynamic therapy?

A clinician applies a photosensitising medicine to the target area and allows it to absorb. A specific light then activates the medicine, creating a reaction that can damage selected unhealthy cells. The approach may be used for some sun-damaged changes and certain superficial skin cancers, including appropriate basal cell carcinoma. It is different from ordinary cosmetic light treatment because the medicine and light are chosen as a pair.

During activation, warmth, stinging, or discomfort can occur. The treated skin may become red, swollen, crusted, or tender before it settles. Suitability depends on the lesion, its depth, location, skin condition, and whether a sample or another treatment is needed.

Follow the clinic's instructions about cleansing, medicines, and the time to avoid strong light. After treatment, protect the area from daylight and bright indoor light for the period advised; ordinary sunscreen alone may not provide enough protection during the sensitive window. Wear covering clothing, avoid picking crusts, and use only the recommended cleanser or moisturiser.

Tell the clinician about medicines that increase light sensitivity, a history of unusual reactions to light, active skin infection, or difficulty avoiding light after treatment. Keep follow-up appointments so the treated area can be checked and any further care arranged.

Contact the treating team promptly if pain is severe or worsening, swelling spreads, blisters develop, the area becomes increasingly hot, or pus and fever appear. Seek urgent medical help for facial swelling that affects breathing or vision. A sore that fails to heal, bleeds repeatedly, or changes after treatment also needs review rather than repeated self-treatment.

Ask which diagnosis is being treated, why this light-and-medicine approach fits the lesion, how long light precautions last, what pain relief is suitable, and how healing will be assessed. Ask whether a biopsy, another session, or an alternative such as topical 5-fluorouracil is more appropriate.