"I've taken medication and tried squeezing, but the acne keeps coming up over a wide area — I heard there's a treatment done with light?"
"How is this PDT thing different from a laser?"
These are questions people worried about recurring acne have been asking a lot lately.
Hello, I'm Director Kwon Si-jin & Yoon Ju-hyun at DA Clinic Myeongdong ^^
We're getting ready to open our doors in Myeongdong soon, and since so many people have been asking about PDT ahead of our opening, we wanted to put together this overview for your information first.
Getting it while thinking you just shine a light really means going in knowing only half of it, so let me honestly start with the principle.
PDT isn't a 'treatment where you just shine a light' but a two-step treatment where you 'first apply a medication, then make that medication react to light.'
PDT Is a Treatment Where You Apply a 'Photosensitizer' and Then Shine a Light
Let me first get the principle down.
PDT (photodynamic therapy) is a treatment where a light-reactive photosensitizer is applied to the skin, absorbed for a set time, and then a specific wavelength of light is shone to trigger its action.
The key is that it isn't the light itself, but that the pre-applied medication meets the light and becomes activated, acting on the sebaceous glands and areas of inflammation.
A match does nothing if you just leave it, but it lights only when it meets the condition of friction. Likewise, PDT's action begins only when the two conditions of the photosensitizer and light meet.
That's why there's a waiting time to apply and absorb the medication, and then the light is shone in that order, which is what differs from an ordinary laser.
It's Mainly Used for Moderate-or-Above Acne and Sebum Activity
It's quicker to understand if we look at what conditions PDT is used for.
Rather than light little bumps, it's often used for moderate-or-above acne that recurs over a wide area or has high sebum activity.
As the photosensitizer is activated, it works on the sebaceous glands producing excess sebum and on areas of inflammation, so it's used, after judging the indications, for chronic acne that keeps coming up in the same spot.
It's also considered as another approach when oral or topical medications don't quite bring it under control, or when medication is hard to use for a long time.
That said, it isn't needed for all acne. After diagnosing the type, depth, and sebum condition, we think it's right to recommend it in stages only to those for whom it suits.
It Tends to Be Done Over Several Sessions Rather Than One
PDT too is closer to a treatment built up over several sessions than one that ends in a single go.
Sebaceous gland activity and inflammation are hard to sort out in one shot with a single treatment, so we watch the response over the sessions and adjust the intensity and interval.
Usually we proceed at intervals of a few weeks, finely matching the photosensitizer concentration and the light-shining conditions session by session.
So rather than nailing down the number of sessions at the start, it's more reasonable to coordinate the needed sessions together while watching how it progresses.
The number of sessions needed and the degree of response differ from person to person depending on the pattern of the acne and the skin condition. (The degree of improvement varies by individual)
After the Treatment, 'Photosensitivity' Care Matters Above All
This is the part I'll speak about with the most care.
Because PDT is a treatment where a photosensitizer is applied, the skin enters a 'photosensitive' state where it's sensitive to light for a set period after the treatment.
If it touches strong light or UV during this period, unintended irritation or redness can grow, so for a few days after the treatment, actively avoiding light and UV is the key part of care.
So on the day of the treatment and for a few days after, it's good to avoid strong sunlight, pay attention to UV protection and covering up when going out, and keep your distance from strong lighting even indoors.
Right after the treatment, redness, flaking, or stinging can occur, and these usually settle over a few days. That said, the degree and duration differ from person to person depending on the photosensitizer concentration and skin condition.
Just keeping this photosensitivity care makes recovery much more comfortable, so it's good to approach it with the mindset of tending to the aftercare even more than the treatment.
People in These Situations Should Check One More Time
PDT isn't a treatment casually recommended in every situation.
Because it's a treatment that uses a photosensitizer and light, if you have a constitution oversensitive to light or you're taking a photosensitizing medication, it's safer to check your condition first and then decide whether to proceed.
If your skin barrier has weakened a lot, or there's an ongoing wound or severe inflammation at the area, it's better to calm it down first and then adjust the timing.
If you're pregnant or have a specific condition or medication, the suitability has to be weighed separately, so if you let us know in advance, we'll set the direction together.
And to say one more thing honestly: acne is a chronic, recurring condition for which it's hard to promise a 'cure.' PDT too is closer to an approach of managing it well to maintain a clear state than a treatment that makes it disappear forever in one shot, and knowing that in advance will put your mind at ease.
Frequently Asked Questions
Q. How is PDT different from a laser?
A. Unlike an ordinary laser that uses only light, PDT is a two-step treatment where a light-reactive photosensitizer is applied first and then light is shone. It isn't the light itself that acts, but the pre-absorbed medication that meets the light and becomes activated, acting on the sebaceous glands and areas of inflammation. So there's a separate waiting time to apply and absorb the medication, and after the treatment, photosensitivity care becomes more important as the skin becomes sensitive to light. Which approach suits which condition varies depending on the pattern of the acne and the skin condition, so it's better to decide after a diagnosis. The degree of response differs from person to person.
Q. Can I go out right after getting PDT?
A. Right after PDT, you're in a photosensitive state where the skin is sensitive to light, so on the day of the treatment and for a few days after, it's good to actively avoid strong sunlight and UV. If it touches light as is during this period, redness or irritation can grow. If you need to go out, pay attention to UV protection and covering up, and it's safer to avoid the times when strong sunlight comes in. It's also good to keep your distance from strong lighting even indoors. The period the photosensitivity lasts varies depending on the type and concentration of the photosensitizer, so keeping to the care period you're advised after the treatment helps your recovery.
Q. About how many times should I get it?
A. PDT is usually done over several sessions at intervals of a few weeks rather than just once. Sebaceous gland activity and inflammation are hard to sort out in one go, so it's an approach where we watch the response over the sessions and adjust the intensity and interval. Since we finely match the photosensitizer concentration and light-shining conditions session by session, rather than nailing down the number at the start, it's more reasonable to coordinate it together while watching the progress. The number of sessions needed differs from person to person depending on the pattern of the acne, the sebum condition, and the skin's response. Please keep in mind that there are individual differences in the degree of improvement.
In Closing
If I sum up today's content in one line, it's this.
PDT isn't a 'treatment where you just shine a light' but a treatment that has to go together with 'the photosensitizer and light, plus post-treatment photosensitivity care.'
If you've grown weary of acne that medication just won't bring under control, I completely understand that feeling. But if you first go over the principle and the aftercare of photosensitivity, recovery is much more comfortable and you can go further. Just please remember that there are individual differences in the response and the result.
This isn't an article recommending a treatment, but an informational article we've put together for your reference while preparing to open.
DA Clinic Myeongdong is set to open soon. We'll share news of our opening and treatment information first on our blog and Instagram ^^
Thank you for reading this long piece. This was Director Kwon Si-jin & Yoon Ju-hyun at DA Clinic Myeongdong.
This column is an informational article meant to provide general medical information, and the effects and side effects of treatments may vary by individual. DA Clinic Myeongdong is set to open soon. (Medical Service Act Art. 56)