Last Updated on November 12th, 2019
Photodynamic therapy is a tool for treating acne that utilizes the interactions of certain wavelengths with acne bacteria and the skin itself. Blue light kills acne bacteria on the skin. Red light heats and shrinks oil-producing sebum glands in the skin. And the use of red and blue in a pulsating, photodynamic acne treatment system minimizes the risk of accidental overheating or burning of the skin. But light treatment is never enough all by itself to get rid of acne for good.
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For centuries, acne sufferers were advised to let the sun “dry out” their acne. It turns out that it is never a good idea to use the sun or anything else to dry out the skin to treat acne, because dry skin is tight skin, and tight skin traps sebum and bacteria in pores. The visible blue light from the sun, however, actually does treat acne by killing acne bacteria.
Acne bacteria have chemicals in their protective membranes called porphyrins. One of the poryphorins in the protective barrier of the acne bacterium resonates with visible blue light of wavelengths between 407 and 420 nanometers. These blue pigments in the bacteria respond to the blue light in a photodynamic fashion that causes them heat up and burst the membrane. Oxygen from the surrounding pore attacks the organelles inside the bacterium, and most acne bacteria, about 99.99% of all acne bacteria, die within 48 hours of exposure.
Blue light therapy has a tremendous advantage over antibiotics since bacteria cannot develop genetic resistance to the therapy, and the treatment will not create a resistant strain. Even better, the skin itself is undamaged by these wavelengths of light. UV light is not necessary to kill the bacteria.
Killing acne bacteria does not clear up blemishes instantly. Bacteria do not actually cause inflammation in the pore. The immune system’s over-reaction to the presence of bacteria is what causes itching, irritation, and, at least in part, hardening of sebum. When the bacteria die, their stimulation of the immune system stops, and the blemish can begin to heal. The skin of teenagers and young adults, however, can begin to heal within 48 hours of blue light treatment. Daily cleansing will keep blemishes away once the skin has cleared.
Bacteria and the immune system’s reaction to them is only part of acne. Another part of the problem is the over-production of sebum. Stopping the over-production of sebum can help the skin keep pores open.
The sebaceous glands that make sebum are located beneath the pores. They cannot be reached by blue light. They can, however, be reached by red light. When the skin is irradiated with visible red light, sebaceous glands are heated, and shrink. Although it is possible to irritate the skin so much that there is a rebound reaction in which pores actually fill with even more sebum, a mild dose of red light may be just enough to stop the production of new whiteheads and blackheads.
To prevent skin damage by red light treatment, dermatologists have devised treatment devices that deliver pulses of blue and red light. The idea is to heat the lower layers of the skin just enough to reduce oil production without damaging the skin.
It is very rare for any acne treatment to be completely successful. Most studies comparing photodynamic therapy find that it gets rid of about half of whiteheads and blackheads and about 2/3 of pimples after a month of weekly treatments. Benzoyl peroxide, by comparison, is usually about 50% as successful. But should everyone use light therapy no matter what their skin type?
Here are some important considerations:
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