Photodynamic Acne Therapy
What is Photodynamic Therapy?
Photodynamic Therapy (PDT) is a treatment that combines a photosensitizing agent (a drug that is activated by light) and a special light source in order to treat specific skin conditions. PDT is used to treat a variety of skin conditions, but the two most common ones are pre-skin cancers called actinic keratoses and moderate to severe acne.
The photosensitizer used in PDT is Aminolevulinic acid (ALA), which is also known as Levulan. When undergoing PDT, Levulan is applied to the skin and allowed to incubate for a short period of time (usually 30 minutes to 2 hours). ALA is then preferentially absorbed by certain cells (such as pre-cancerous cells or areas of active acne). A light is then applied to the treated area (blue light, red light or laser light) which activates the ALA and has the effect of destroying the cells that absorbed the medicine (i.e. pre-cancerous cells or acne).
How does Photodynamic Therapy work in acne patients?
PDT is thought to treat acne by two primary mechanisms. First, it shrinks the skin’s oil glands (sebaceous glands) that contribute to acne formation. This can drastically reduce the amount of oil within the pores, thereby reducing comedones (blackheads and whiteheads). Second, PDT also kills the bacteria (Propionibacterium acnes) that live on facial skin and cause acne breakouts. In addition, PDT seems to improve the skin’s overall texture, and may speed the resolution of acne-induced discoloration (red or dark spots that remain after the pimples have resolved).
Is there evidence to support the safety and efficacy of PDT for acne?
There have been over 21 clinical studies evaluating PDT for the treatment of acne. These studies demonstrated that PDT is a safe and effective treatment for patients with acne.
Can you describe a treatment session?
First, excess dead cells on the skin’s surface are removed using an acetone scrub. This enhances the penetration of the photosensitizing agent. Next, the photosensitizing agent (Levulan) is applied to the skin and allowed to incubate for a period of 30 to 90 minutes. The agent is then removed and the skin is treated with light for about 15 minutes. Most commonly blue light, laser light or red light is used to activate the Levulan.
Many patients report feeling moderate warmth during the procedure but most do not feel any pain. Patients must avoid sun exposure for 2 days after the treatment.
How many treatments are required?
A series of two to five treatments are usually performed at two to four week intervals. The number of treatments recommended depends on the severity of acne. Some patients may notice results after the first treatment.
The majority of patients report significant improvements ranging from a 50% to 75% reduction in acne lesions after a few treatments. However, a small amount of patients show only modest improvements and results vary for each individual patient.
The side effects of PDT for Acne may include redness and/or peeling of the treatment site. It has been described as being similar to a sunburn. It is generally mild and resolves in 1 to 8 days.
Photodynamic Therapy is an exciting new treatment for acne that has been well studied and benefits the majority of patients who undergo treatment. It is a great addition to our armamentarium against acne and may be particularly helpful to those who have unsuccessfully tried several therapies and are looking for something new. It is also a good treatment for those who are looking for a “jump start?to their existing acne treatment regimen.
Other Uses for Photodynamic Therapy
Pre-skin Cancers and PDT
Many patients over age 40 have pre-skin cancers or actinic keratoses (AKs). Clinically, these are red, scaly rough patches of skin most often on the face, back of hands, and arms. There are many different ways to treat AKs including freezing with liquid nitrogen, applying a chemotherapy cream (for 30 days) or using PDT. Many patients have found PDT to be a superior treatment because it is less painful then freezing, is faster and more convenient then using a chemotherapy cream, and has the added benefit of reducing fine lines and improving pigmentation. Usually only one or two treatments are needed.
Additional Indications for PDT
Sebaceous Gland Hyperplasia
Mild to moderate wrinkles
Large pore size
Hidradenitis Suppurativa (boils in underarms and groin)
Basal Cell Skin Cancer
Skin cancer prevention
Side Effects of PDT
Most people experience mild burning and itching for about one hour after the procedure, although this can last a day or two. Mild to moderate redness may also be experienced for one to several days after treatment depending on the intensity of the treatment. After PDT, a small amount of activated substance remains in the skin for 24 to 48 hours. Sunlight and even indoor light may affect this and cause a sunburn like response. Use of sunscreen and a hat may diminish these undesired effects.