Blue Light Photodynamic Therapy is a two-step process and a common treatment of Actinic Keratosis on the face and scalp. Step one is the application Levulan Kerastick solution uniformly to the treatment area. Patients then wait the recommended amount of time (typically 2 hours) in order to allow the solution to penetrate the damaged cells. During the second part of the treatment, the patient will be placed in front of the Blu U Light Therapy model and will generally be exposed to the blue light for around 17 minutes. It is important to know that not everyone is suited for this treatment. Types of patients that should not be given this treatment include, but are not limited to, patients with skin sensitivity to wavelengths of 400-450 nanometers. Common side effects seen by patients include scaling and/or crusting, hypo/hyper-pigmentation, itching, stinging and/or burning, erythema and edema. According to some studies, at least 50% of patients have reported severe stinging and/or burning at one or more lesions being treated at some time.