Photosensitizers make the body sensitive to light. The period of time over which a patient is sensitive, and therefore should avoid light exposure, varies according to the type of photosensitizer used, but can last up to 6 weeks after treatment. Patients are given light precautions, including avoidance of direct sunlight and bright indoor light for the period of sensitivity. If light precautions are not followed, there is the possibility of sustaining burns, swelling, and pain. Other side effects of PDT are related to the area that is treated and can include coughing, trouble swallowing, stomach pain, painful breathing, local swelling, and/or shortness of breath.