Photodynamic therapy uses a light-sensitive drug that is activated inside the body by laser light to kill cells, usually cancer cells. First, you receive a special drug — typically by injection — that is absorbed by cancer cells. One to three days later, your doctor applies a laser light to the targeted areas, which causes cancer cells to be killed by reacting with oxygen. Photodynamic therapy also appears to damage blood vessels in tumors and to activate the immune system to attack cancer cells.

For surface tumors such as skin cancer, your doctor may put a drug on the skin and use light-emitting diodes (LEDs) instead of lasers.

Photodynamic therapy treatments may be repeated. This therapy can be used alone or in combination with other treatments, such as surgery, chemotherapy or radiation therapy.


In photodynamic therapy, the combination of the laser and the drug causes a chemical reaction that destroys the targeted cells. This is a two-part treatment:

  1. First, the doctor applies the light-sensitive drug (photosensitizer). For internal conditions, such as esophageal or lung cancer, the drug is injected into your vein. The drug is absorbed into your body, especially by fast-growing cancer cells.
  2. One to three days later, the doctor inserts a thin, lighted, flexible tube (endoscope) into the area that needs treatment — for instance, your esophagus (the muscular passageway that runs from your throat to your stomach) or your lungs. Through the endoscope, the doctor shines a high-powered laser light (different from radiation therapy or heat-producing lasers) onto the diseased tissue to activate the drug.

Photodynamic therapy is used to treat conditions such as:

Side effects can occur with photodynamic therapy, including:

  • Sensitivity to light, which means you'll need to avoid any bright light, including the sun, for several weeks to prevent sunburn, redness and swelling.
  • Swelling and inflammation around the site being treated, and other signs and symptoms, depending on the treatment site, such as pain or trouble swallowing or breathing from treatment of the esophagus.
  • Expertise and experience. Mayo Clinic doctors were the first to use photodynamic therapy in humans in the late 1950s, pioneering its application in the lung and GI tract. The clinic remains on the forefront in researching and using this therapy.
  • Team approach. Mayo Clinic's team approach to treatment means specialists from different areas work together to develop a treatment program for your specific needs.

At Mayo Clinic, we assemble a team of specialists who take the time to listen and thoroughly understand your health issues and concerns. We tailor the care you receive to your personal health care needs. You can trust our specialists to collaborate and offer you the best possible outcomes, safety and service.

Mayo Clinic is a not-for-profit medical institution that reinvests all earnings into improving medical practice, research and education. We're constantly involved in innovation and medical research, finding solutions to improve your care and quality of life. Your doctor or someone on your medical team is likely involved in research related to your condition.

Our patients tell us that the quality of their interactions, our attention to detail and the efficiency of their visits mean health care — and trusted answers — like they've never experienced.

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Mayo Clinic doctors were the first to use photodynamic therapy in humans in the late 1950s, and the clinic remains a pioneer in researching and using this therapy.


See a list of publications by Mayo Clinic doctors on photodynamic therapy on PubMed, a service of the National Library of Medicine.

Jun. 16, 2011