How does light therapy work and what acne does it treat best? A dermatologist explains.

Anyone who’s ever experienced the struggles of acne, as a teen or in their adult years (or both, if you’re lucky like me), would have considered all manner of treatments in the quest for clear skin.

There are so many pills, creams, treatments and cleansers that claim to be the cure-all for acne out there, and it can get confusing, expensive and disappointing when they don’t work.

One such treatment that many people swear by is light therapy treatment.

It’s the treatment of the stars that boasts a potential solution to troublesome skin, keeping your constant desire to hide under layers of make-up at bay.

But how do you know if it’s the right option for you? And with blue and red light therapy both available – which is the most effective? Do they work in conjunction, or separately?

We have lots of questions, so we consulted dermatologist Dr Garry Cussell, owner of Rejuvenation Clinics of Australia, to find out the ins-and-outs of light therapy for acne treatment.

First off, Dr Cussell, who has been a doctor for 42 years and a physician for 20, explained that acne is a “very complex situation”, adding that light therapy treatment may not work for everyone.

“We don’t want people to believe that simply buying a phototherapy blue light or red light, or even going to a salon, is going to do a lot of things because there are so many factors to do with the control and management of acne,” Dr Cussell said, in reference to the at-home masks available for purchase.

“We still have problems controlling many people’s acne, and a lot of people get very frustrated when they’re trying something that’s given a lot of promise and it doesn’t clear up their skin.”

What exactly is light therapy, and how does it work?

“It originated in the ’90s,” Dr Cussell said.

“The big breakthrough was the discovery that acne’s bacteria (Propionibacterium acnes or P. acnes for short) – the main bacteria involved with the inflammation and infection and therefore the soreness in acne – can be killed with the blue light, a non invasive light, and not ultraviolet, so it doesn’t cause any damage.

“It basically oxidises a chemical in the cell wall of the bacteria and kills the bacteria, so when that was discovered it started to be used, and there have been a lot of variations since then.”

What about red light therapy?

“The red light is used in the same way, but it doesn’t kill the bacteria – it reduces the inflammation and the redness associated with it so helps with the healing process. We use them in conjunction,” Dr Cussell explained.

“So basically, the blue light is very effective in killing the main offending organism in causing acne inflammation, which can often cause scarring and pigmentation, and the red light phototherapy, in a different wavelength, helps with inflammation and also promotes healing with a little bit of collagen.”

What does the collagen do?

“People overemphasise the fact that it uses a lot of collagen. It’s just an aid in improving the speed of healing, so it does help reduce scarring,” Dr Cussell said.


“The most important therapy for acne is collagen peptides – it’s an active compound in serum. It’s the same as trying to promote scar repair by using antioxidants, vitamin A, B and C, and trying to prevent pigmentation with serums morning and night.

“There are other advances in using collagen peptide masks in addition to using phototherapy to help healing. We can do that in our clinics, but we prefer to use these from home with a compacted serum every morning and night.”

So, in a nutshell, the blue light kills the bacteria, the red light helps with inflammation, and the collagen helps reduce scarring.

Dr Cussell says light therapy is better at treating "inflamed acne". Image: Getty.

How many light therapy sessions are needed before you start seeing results?

"Generally, we recommend coming in twice a week, every week for four weeks and then you start to see a response then," Dr Cussell said.

"Some people continue with it for eight weeks."

He added: "[The blue and red lights] are combined together - so you only need to have the one session with the one light. Twenty minutes is all you need to kill the bacteria, but the bacteria does keep growing.

"Because the bacteria grow in an environment where the oil can't escape, you need to do it repeatedly. [Light therapy] is not a cure for acne, the bacteria builds up once the oil glands block up - so the most important thing is to try and unblock the sebum plugs with topical treatment, and try and get them to drain out in the first place.

"This is why good exfoliates and cleansers - particularly lactic acid cleansers, oil reducing serums and the vitamin antioxidants - are so important."

What type of acne does light therapy treat?

"[The blue light] kills the PH bacteria, but they don't kill the surface bacteria as such," Dr Cussell explained.

"To explain that - the P. acnes bacteria are normal bacteria found in everyone's oil, usually they don't do any harm. What happens with acne is the oil gland is blocked, and the sebum plug doesn't allow the oil to escape, so oil builds up under the skin, and then you get an overgrowth of P. acnes bacteria and that's what causes inflamed pimples and cysts and acne. That's what the phototherapy cures."


"It'll help with all acne - but it is better with inflamed acne, where there's a lot of P. acnes bacteria and the pimples are more inflamed, red and sore to touch, and trapped under the skin," he added.

"The oral antibiotic we use for acne will kill the surface bacteria and help to reduce the inflammation, but they don't kill this particular bacteria - which is why light therapy is so successful in treating.

"People who just have trapped oil, without a lot of bacterial infection - that's more your blackheads - and your non-inflamed acne isn't going to respond so well. But most of the inflamed acne and most of the adult hormonal acne is very inflamed and that will respond."

Are there any side effects to light therapy?

"Usually not - but for some people it does backfire and they get an increased inflammation after blue light and red light therapy. That's the exception - but you can never say it's going to work for absolutely everyone," Dr Cussell said.

Is this type of light therapy used for anything else?

"The red light phototherapy we use for many other conditions apart from acne. It helps reduce inflammation and redness with other treatments using various specific lasers. We use red light immediately afterwards to help with swelling and redness so people can get a quicker recovery - so they're very versatile," Dr Cussell said.

"We've got a whole range of  lasers we use - from Q-switch, to Pico laser, to Q-switched ruby lasers, high-peel therapy - we've got 15 different types of lasers and about 50 lasers in our practices, and it's very complex."

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