Photodynamic therapy uses medications called photosensitizers to boost the activity of a light-based skin treatment.

It is a form of phototherapy or light therapy and is becoming more popular as an acne treatment, particularly for severe cases that do not respond to other treatments.

Photodynamic therapy (PDT) may also be effective for other skin conditions, such as sun-damaged skin, precancerous cells, and skin infection.

Fast facts on photodynamic therapy

  • A review of more than 70 studies suggests that, generally, PDT for acne produces favorable results, especially for people who do not respond well to topical or oral treatments.
  • It may take several sessions to see the benefits of photodynamic therapy for acne.
  • People with more severe forms of acne may experience the most significant improvements. Results tend to be semi-permanent, lasting for several months or longer.
  • Because photodynamic therapy is a relatively new treatment for acne and other skin conditions, any long-term effects are not known.

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PDT attempts to treat acne with intense pulsed light.

Photodynamic therapy requires three components:

  1. a photosensitizer
  2. a light source
  3. oxygen

Photosensitizers are topically applied solutions that cause certain types of abnormal cells to produce light-absorbing molecules called porphyrins. This change allows the light treatment to target the abnormal cells that are contributing to the acne.

The use of photosensitizers distinguishes PDT from other forms of phototherapy.

After applying a topical photosensitizer, a medical light source is focused on the skin to activate it. This light source may provide blue light, red light, or intense pulsed light (IPL). A doctor will decide what light source is best for the individual. Combined with the photosensitizer and the presence of oxygen, the light helps to destroy acne cells and bacteria.

Photodynamic therapy also reduces the size and activity of the oil-producing glands on the skin, known as the sebaceous glands.

Overactivity and inflammation of these glands contribute to acne development.

Is photodynamic therapy effective for acne?

PDT tends to be more effective for inflammatory, rather than non-inflammatory, acne.

For example, some research found that participants experienced a 68 percent decrease in inflammatory lesions 12 weeks after PDT treatment, when compared with a control group, but no reduction in the number of non-inflammatory lesions.

Other research shows inflamed lesions were reduced by more than 70 percent 16 weeks after the beginning of photodynamic therapy.

However, a variety of photosensitizers, light sources, and other treatment variables are used in the studies. For this reason, a 2016 research review suggests that standard guidelines should be developed and tested for PDT therapy in the treatment of acne.

PDT tends to be more effective for inflammatory, rather than non-inflammatory, acne.

For example, some research found that participants experienced a 68 percent decrease in inflammatory lesions 12 weeks after PDT treatment, when compared with a control group, but no reduction in the number of non-inflammatory lesions.

Other research shows inflamed lesions were reduced by more than 70 percent 16 weeks after the beginning of photodynamic therapy.

However, a variety of photosensitizers, light sources, and other treatment variables are used in the studies. For this reason, a 2016 research review suggests that standard guidelines should be developed and tested for PDT therapy in the treatment of acne.

Photodynamic therapy costs vary widely depending on several factors, including the severity of the acne and the part of the country where treatment is received.

PDT can cost anywhere between $100 and $400 or more per session. Up to five sessions may be required at a time. Results are not permanent, so follow-up sessions will be necessary to control acne symptoms long-term. Post-treatment skincare products may also be required and may cost extra.

There is no insurance coverage for PDT.

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PDT reduces the activity of the acne-causing sebaceous glands beneath the skin.

Photodynamic therapy may offer benefits over other therapies. Its positives include:

  • killing acne-causing bacteria on the skin
  • affecting only targeted cells, helping to maintain skin integrity
  • reducing the size and activity of sebaceous glands
  • helping fade old acne scars
  • not causing scarring
  • treating other skin conditions that may co-occur alongside acne, such as age spots and rosacea
  • can be used along with medication if needed, except isotretinoin (Accutane)

Another important benefit of photodynamic therapy is that it does not involve the use of antibiotics or oral retinoids, such as Accutane. This makes PDT a viable treatment for people who cannot take those medications.

PDT may be especially beneficial for people with severe acne or those whose acne has not responded well to other treatments.

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PDT uses topical photosensitization medicine to prime the skin for phototherapy.

Photosensitizers are prescription medications. Therefore, PDT treatment must be carried out by a dermatologist or other doctor.

Prior to treatment, the skin will be cleansed and treated with microdermabrasion or a scrub. This helps reduce blackheads and acne pustules.

The photosensitizing agent is applied to the skin for between 15 minutes and several hours, depending on the location and severity of the acne and the person's skin type. This provides adequate time for the agent to absorb into the skin cells and the sebaceous glands.

Some people may experience a stinging sensation during this portion of the treatment, which should gradually subside.

Next, a medical light source is shone on the skin for 8-20 minutes. The light activates the photosensitizing agent.

At this stage of the procedure, some people may experience a stinging or burning sensation, the intensity of which varies.

After treatment, the skin is extremely sensitive. People must stay indoors, out of sunlight, for 48 hours following treatment. This is because the photosensitizing agent makes skin sensitive to sunlight, so there is a risk of severe burns from sun exposure.

Sunscreen does not provide adequate protection during the period just after treatment.

People should discuss using topical acne lotions, makeup, and other skin products with a doctor following PDT. In particular, people may need to avoid products that contain oils or waxes for a period.

Follow-up sessions

The number of treatments required depends on the person's skin type, the number of lesions they have, and how severe those lesions are.

Anywhere between two and five sessions are necessary, at 2-4 week intervals, for optimal results. Some people may notice results after a single session.

Several adverse effects may arise following PDT, including:

  • mild to moderate pain
  • peeling skin
  • skin redness
  • crusting of the skin
  • tightness
  • swelling
  • itching
  • acne flare-up

These effects are most intense in the 48 hours following treatment and usually subside after a week.

Long-term effects and risks

The sebaceous glands excrete oil (sebum) to lubricate the skin and protect it from microbes. While people with acne tend to have larger and more active sebaceous glands, and reducing their activity may reduce acne, the long-term effects of reducing sebum production are not known.

People with lupus, porphyrin allergies, or a rare blood disorder called porphyria that causes heightened sensitivity to light, should avoid PDT.

In rare cases, some people may experience an allergic reaction to the photosensitizing solution.

Discuss the benefits, effects, and risks of PDT with a doctor before commencing therapy.