For about a decade now, dermatologists have begun providing in-office light therapy to their patients in a 2 step procedure which helps traditional light therapy work better by helping to shrink sebaceous (oil) glands, albeit with more side effects. Photodynamic therapy is normally administered 3-5 times at 2-4 week intervals and is often reserved for moderate to severe acne because of the seriousness of the procedure and the downtime involved.

First, a photosensitizing agent, most commonly either a 20% solution of Levulan® (5-aminolevulinic acid - ALA) or a 20% solution of methyl aminolevulinate (MAL) is applied and allowed to incubate on the skin under an occlusive dressing for up to 3 hours. This 3-hour incubation time allows the photosensitizing agent time to be absorbed into the skin and into the sebaceous (oil) glands.

Next, red and/or blue light is shone on the skin, normally for 15-20 minutes. This light activates the photosensitizing agent, which kills acne bacteria and helps shrink oil glands.

This is a critical topic when it comes to acne and something that may account for the limited or entire lack of success some people experience with PDT. Red light, because of its longer wavelength, penetrates deeper into the skin than blue light. According to a 2014 review article in the journal Clinical Cosmetic and Investigational Dermatology, "Although blue light allows sufficient tissue penetration for the treatment of thin actinic keratosis (small, rough, raised areas found on areas of your skin), red light penetrates deeper and is more effective for the treatment of thicker lesions and deeper targets such as the sebaceous gland...The literature has focused primarily on MAL-PDT followed by red light because targeting of the sebaceous glands is optimized with this regimen."1 If your dermatologist wants to use only blue light for PDT, you may want to ask why this is the case.

This is also an important topic and one that may partially account for the frustration of people who do not achieve the results they desire with PDT. With acne in particular, methyl aminolevulinate (MAL) may be a better choice since it may have a higher affinity for fatty environments like sebaceous glands and the sebum (skin oil) therein. MAL may also achieve deeper skin penetration than ALA. The length of time that the physician allows the chosen photosensitizer to incubate is also important to the success of PDT. Some evidence is showing that a full 3-hour (180 minute) incubation time may be best.1 Due to crowdedness inside doctor's offices and the desire for patient turnover, this incubation time can be cut short, potentially sacrificing results. Be sure to carefully ask your doctor about incubation time.

photodynamic therapy MAL
photodynamic therapy ALA

photodynamic therapy side effects

In contrast to at-home light devices without photosensitizing agents, patients undergoing photodynamic therapy in a dermatologist's office can expect to experience pain during treatment, sometimes severe. Side effects are also much more pronounced when photosensitizers are used and include redness, swelling, itching, and peeling and/or crusting for a week or so, as well as occasional hyperpigmentation (skin darkening) that can last for a month after the procedure and is more common in people of darker skin types. Most people prefer not to leave the house for several days after the procedure. Patients may also experience a flare of acne that is transient in nature and should subside. Because the skin is highly photosensitized, it is also imperative that patients stay completely out of the sun and even bright indoor light for 2 days after treatment.

Side effects vary depending upon the type of photosensitizer used, with MAL tending to produce the most severe pain during treatment and potentially a higher chance of hyperpigmentation. Researchers are currently performing studies on lower concentrations of photosensitizers to gauge whether this will provide the same results with less side effects.2-3 Researchers are also looking into other photosensitizers that produce less pain, fewer side effects, and require shorter incubation times, such as Indole-3-acetic acid (IAA) with green light.4

Results from studies point toward an average reduction in inflammatory acne of about 75% after 3 treatments.5-15 When results are experienced, they tend to be semi-permanent. Follow up from studies normally end no later than the 3 month point, so it is hard to tell how long results last, but some dermatologists report 1 or even 2 year reduction in symptoms. Since PDT is a relatively new procedure, we will know better how long results last as time goes on. Reviews on are mixed, but keep in mind that the type of photosensitizer, incubation time, and light source used tends to vary depending on the procedure the reviewer has undergone. If you decide to undergo photodynamic therapy, please leave your review once you are finished, or better yet, start a gallery of your progress and allow us to follow along.

Each treatment costs on average about $400 and is normally not covered by insurance. To inquire about treatment, contact your dermatologist.

  1. Wan MT, Lin JY. "Current evidence and applications of photodynamic therapy in dermatology." Clinical, Cosmetic and Investigational Dermatology. 2014; 7: 145-163.
  2. Ma L, et al. "Low-dose topical 5-aminolevulinic acid photodynamic therapy in the treatment of different severity of acne vulgaris." Photodiagnosis and Photodynamic Therapy. 2013; 10(4): 583-90.
  3. Asayama-Kosaka S, Akilov OE, Kawana S. "Photodynamic Therapy with 5% Aminolevulinic Acid is Safe and Effective Treatment of Acne Vulgaris in Japanese Patients." Laser Therapy. 2014; 23(2): 115-20.
  4. Huh SY, et al. "The effect of photodynamic therapy using indole-3-acetic acid and green light on acne vulgaris." Annals of Dermatology. 2012; 24(1): 56-60.
  5. Hong JS, et al. "Acne treatment by methyl aminolevulinate photodynamic therapy with red light vs intense pulsed light." International Journal of Dermatology. 2013; 52(5): 614-619.
  6. Wiegell SR, Wulf HC. "Photodynamic therapy of acne vulgaris using 5-aminolevulinic acid versus methyl aminolevulinate." Journal of the American Academy of Dermatology. 2006; 54(4): 647-651.
  7. Hongcharu W, et al. "Topical ALA-photodynamic therapy for the treatment of acne vulgaris." Journal of Investigative Dermatology. 2000; 115(2): 183-192.
  8. Pollock B, et al. "Topical aminolaevulinic acid photodynamic therapy for the treatment of acne vulgaris: a study of clinical efficacy and mechanism of action." British Journal of Dermatology. 2004; 151(3): 616-622.
  9. Akaraphanth R, Kanjanawanitchkul W, Gritiyarangsan P. "Efficacy of ALA-PDT vs blue light in the treatment of acne." Photodermatology, Photoimmunoloty & Photomedicine. 2007; 23(5): 186-190.
  10. Horfelt C, et al. "Topical methyl aminolaevulinate photodynamic therapy for treatment of facial acne vulgaris: results of a randomized, controlled study." British Journal of Dermatology. 2006; 155(3): 608-613.
  11. Weigell SR, Wulf HC. "Photodynamic therapy of acne vulgaris using methyl aminolaevulinate: a blinded, randomized, controlled trial." British Journal of Dermatology. 2006; 154(5): 969-976.
  12. Pinto C, et al. "Efficacy of red light alone and methyl-aminolaevulinate photodynamic therapy for the treatment of mild and moderate facial acne." Indian Journal of Dermatology, Venereology, and Leprology. 2013; 79: 77-82.
  13. Shaaban D, Abdel-Samad Z, El-Khalawany M. "Photodynamic therapy with intralesional 5-aminolevulinic acid and intense pulsed light versus intense pulsed light alone in the treatment of acne vulgaris: a comparative study." Dermatology and Therapy. 2012; 25: 86-91.
  14. Hong SB, Lee MH. "Topical aminolevulinic acid photodynamic therapy for the treatment of acne vulgaris." Photodermatology, Photoimmunology & Photomedicine. 2005; 21: 322-325.
  15. Goldman MP, Boyce SM. "A single-center study of aminolevulinic acid and 417 NM photodynamic therapy in the treatment of moderate to severe acne vulgaris." Journal of Drugs in Dermatology. 2003; 2: 393-396.