How does light therapy work? The science behind the popular skincare treatment

If you want to learn how does light therapy work, you'll need to understand what it is first. 

Maybe you’ve seen those strange, robotic-looking, red light therapy device masks doing the rounds on Instagram and wondered what on earth they are. Or maybe your local salon has recently started offering LED facials, but you’re not sure what that actually involves. 

The beauty industry can, unfortunately, make it very easy to be bowled over by promises of your best skin yet and bamboozled by science, persuading you into spending vast amounts of money on treatments and gadgets without you really grasping what they do, how they work or whether they’re right for you. 

Light therapy is certainly a treatment that can cause confusion, and a key part of that is because it’s (unhelpfully) referred to by two different names. You might hear it being called light therapy, or by the the acronym LED, which stands for light emitting diode. To help shine a light on how does light therapy work, we’ve enlisted the help of four trusted skin experts to answer the most commonly asked questions.

How does light therapy work? The expert low down

What is light therapy?

“Light therapy is a non-invasive treatment that uses specific wavelengths of light to target various skin concerns and promote skin health,” explains Dr Ifeoma Ejikeme, Medical Consultant Skin Expert and Founder of award-winning Adonia Medical Clinic. Non-invasive means that it doesn’t involve anything physically entering or breaking the skin (unlike Botox, microneedling or filler). 

Instead, the device is placed close to or on top of your skin and “involves exposure to light-emitting diodes (LEDs) or other light sources to stimulate cellular responses in the skin,” Dr Ejikeme adds. The type of light source and the specific wavelengths used are key to how successful the treatment is. This isn’t just any old light, and you won’t get the results of light therapy from simply standing in the sunshine or sitting under a lamp.

Dr Ifeoma Ejikeme

Dr Ifeoma Ejikeme is a consultant, skin expert and founder of the Adonia Medical Clinic. She was voted Best Aesthetic Doctor in the UK for 2023. 

How does light therapy work and what does it do for the skin?

There are different types of light therapy, and each works in varying ways within the skin to treat a range of concerns. The most commonly used forms of light therapy are red and blue, as these have the most clinical evidence behind them to prove that they work. 

So how does light therapy work for each of these treatments? “Blue light can kill the bacteria that drive acne,” says Dr Justine Hextall, Consultant Dermatologist and Medical Director of Tarrant Street Clinic. With this bacteria no longer present, it’s less likely that blemishes will form. “It also reduces activity in the sebaceous gland that produces oil in acne-prone skin,” Dr Hextall adds. It’s best for anyone who finds that their skin is excessively oily, or who is struggling with menopausal breakouts, and wants to reduce existing blemishes as well as prevent new ones from cropping up. If done properly, light therapy for acne can really make a difference. 

If the signs of ageing are a more pressing bugbear for you, then red light is best. These are the kinds of things you want to know before buying a red light therapy device. “Red light helps stimulate the production of collagen and elastin, boosting wound healing and tissue repair and possibly helping to reduce the appearance of fine lines and wrinkles,” says Dr Sophie Shotter, Aesthetic Doctor and founder of Illuminate Skin Clinic.

 If you really want to get into the nitty-gritty science to understand how does light therapy work, Maeve O'Sullivan, Traditional Chinese Medicine Practitioner and Co-Founder of Escapada Health sums it up for us. “Red light exposure is thought to produce a positive biochemical effect in your cells that strengthens the mitochondria, which is where the energy of our cells is created,” she explains. “By increasing the energy of the mitochondria, cells may function more effectively, as well as rejuvenate and repair themselves.” Think of it like giving your skin the energy and tools it needs to behave more like its younger self to smooth out wrinkles. 

You might also come across green and yellow light therapy treatments, but there’s not been enough research yet to back up their claims. “There is emerging evidence for the anti-inflammatory effects of yellow light and the potential collagen-boosting effects of green light,” explains Dr Hextall. The prospect of new treatments is always exciting, so watch this space – there could be more light therapy options coming in the next few years.

Dr Justine Hextall

Dr Hextall is a Consultant Dermatologist and has been working in the NHS for more than a decade. She is the medical director of the Tarrant Street Clinic and an expert in rosacea, acne and skin cancer. 

Dr Sophie Shotter

Dr Sophie Shotter is an award-winning Aesthetics Doctor. She also has a podcast, called Age Well with Dr Sophie Shotter. 

Maeve O'Sullivan

A qualified nurse and Traditional Chinese Medicine Practitioner, Maeve O'Sullivan is the co-founder of Escapada Health, a space for clients to experience a more natural take on health and living. 

Who will see the best results from light therapy?

Now that we understand how does light therapy work, you'll probably want to find out whether it's right for you. You’ll see the best results from light therapy if you want to tackle the concerns that blue and red LED light are proven to treat. “It’s a great treatment for acne, eczema, psoriasis and rosacea – essentially any inflammatory skin condition,” advises Dr Shotter.  

However, light therapy is not necessarily going to transform your skin overnight. It’s more of a slow burner when it comes to results (a turn of phrase – as a treatment it should be pain-free with absolutely no burning sensations) rather than delivering a big, dramatic, overnight change. “Light therapy is for individuals with mild to moderate skin concerns who are looking for gentle treatment options to improve the skin health and appearance,” says Dr Ejikeme. It’s often used in a supporting role, alongside other, more invasive treatments to supercharge the results. A good, experienced practitioner will know exactly how to make the most of it. 

“I use LED light a lot in my clinic alongside other acne and rosacea treatments,” explains Dr Hextall. “I use it with light peels and also post-operatively to stimulate wound healing. Many patients want to minimise downtime, so LED can be used after microneedling or laser to speed recovery.”

Is there anyone that light therapy isn’t suitable for?

Although it’s considered a gentle, non-invasive treatment, there are still some people that light therapy might not be suitable for. To avoid potentially scary side effects, It’s really important to make sure you visit a reputable, reliable therapist who will take these factors into account and clearly explain any risks to you.

“Light therapy may not be suitable for individuals with photosensitive skin conditions, those taking medications that increase sensitivity to light, pregnant women and individuals with certain medical conditions,” explains Dr Ejikeme. “It’s generally suitable for all skin tones, however, blue light is not suitable for those with darker skin tones.” 

Even if you don’t fit into any of those categories, it’s still a good idea to think about your skincare routine before going ahead with the treatment. Dr Sophie Shotter says that her patients can “combine LED with any skin ingredients you wish. This could be active anti-acne ingredients or more gentle hydrating ingredients. But, if you are using retinol, always apply this after your LED session but not beforehand, as the light can provoke reactions.”

Unlike treatments like peels and laser which are best used during the summer months to reduce the risk of triggering hyperpigmentation via sun exposure, “Light therapy is safe to use all year round,” Dr Shotter continues. “Some people find that using it during winter can even help with boosting low mood which is more prevalent in the darker months.” Just make sure you’re protecting your skin post-treatment. “We always suggest shielding the skin from direct sunlight after treatment by carefully applying SPF,” says Dr Hextall. 

What are the differences between at-home light therapy devices and in-clinic treatments?

Although at-home LED devices can be eye-wateringly expensive, if you’re breaking down the cost-per-use then they’re much cheaper than a course of in-clinic treatments. So why would you choose to pay more? It’s all about the access to expertise, plus the strength of light therapy you’re getting. 

“At-home LED is less targeted and significantly less potent,” explains Dr Hextall. “In the clinic, the benefit is that the LED can be programmed to deliver the best combination of wavelengths to manage a skin condition or stimulate rejuvenation. We usually recommend one to two treatments per week and between six and 12 overall depending on the concern we’re treating and how the skin responds.” 

With at-home devices, “the power and number of LEDs is the issue,” says Dr Shotter. “They’re just not powerful enough to give the same results as an in-clinic device. The clinical studies on LED have all been done on powerful, larger devices and therefore the results are not transferable to the mask-type devices people use at home.” 

Ultimately, an at-home mask might help to maintain the results of your professional treatment or make small, incremental improvements to your skin, but it’s not as much of a sure bet as visiting a clinic. It’s up to you whether that’s enough to justify a price tag of upwards of £300 and 10 minutes a day spent looking like a robot, or not.