Background Pain may be a limiting factor in the use of photodynamic therapy (PDT). The consequences of the pain i.e. the resources spent on pain-intervention during routine PDT therapy are poorly described. Objectives To describe the consequences of pain during PDT by describing the use of pain-reducing interventions in routine use. We studied the frequency as well as level of pain-reducing intervention. Methods Descriptive data from PDT treated patients. The level of pain-reducing intervention was graded 0, no intervention; +, cold water spray and ++, pause or nerve block. Results Data from 983 PDT treatments on 579 lesions distributed on 301 patients: 56% did not require pain-reducing intervention, 35% required spraying of cold water, while 9% required pause or nerve block. Ordinate logistic regression revealed an association between lesion size and pain-reducing intervention: the larger the lesion, the more frequent the intervention. Lesion size did not, however, appear associated with the level of intervention. Intervention was most frequently required when treating the scalp/forehead and the extremities. The scalp/forehead also required the highest level of intervention. No significant association between pain-reducing intervention and diagnosis, pre-treatment, gender or age was found. Conclusions Pain-reducing intervention was required in 44% of the PDT treatments. Intervention was particularly required when treating lesions in areas suited for PDT therapy for cosmetic reasons such as the scalp/forehead or extremities. Treatment of large areas more frequently calls for pain intervention than treatment of small areas.