LED Light Therapy for Skin: The Science, Wavelengths and How to Choose a Device

By Charlotte Rye

LED phototherapy has its roots firmly planted in science. NASA first used LEDs (light emitting diodes) for experimental plant growth studies in space, and the technology went on to be developed into medical treatments for everything from skin cancer and mouth ulcers to diabetic wound healing. The possibilities for phototherapy seem endless.

Where LED skin treatment began

The photodynamic therapy (PDT) that led to the LED skin treatments we know today grew out of cancer research in Manchester, linked to the Paterson Institute for Cancer Research. Its optimised intensity and adjustable dose have been used to treat thousands of non melanoma skin lesions with great success.

During that research, clinicians noticed improvements in skin texture and colour, and increased collagen. That observation led to PDT being developed for skin rejuvenation.

Before then, lasers were widely used for resurfacing, collagen regeneration, wrinkle reduction and acne. They used light and heat energy to get results, but they carried higher risks, including hyperpigmentation for some patients, weeks of downtime for some treatments, and a risk of infection.

Then in the early 2000s, the first LED skin therapy devices, such as Omnilux, came to market and changed the face of skin rejuvenation. For the first time it was possible to improve photoageing, scarring, uneven skin colour and acne without lasers or UV light, making treatment suitable for all skin types with zero downtime.

What does the research say?

Current data and clinical studies support the use of red, blue and near infrared light. There is currently little or no evidence for green, yellow, violet or other colours.

One of the best known studies is a controlled trial of 136 volunteers published in Photomedicine and Laser Surgery in 2014. Twice weekly red and near infrared light treatments, over 30 sessions, significantly improved skin complexion and skin feeling and increased collagen density, measured by ultrasound, compared with a control group.

Today, phototherapy is used for a wide range of skin conditions, from acne to psoriasis, without heat or trauma, which makes it an integral part of skin treatment for both therapists and medics.

Understanding wavelengths

We use LEDs everywhere, from phones and computer screens to car headlights. They all emit different colours and wavelengths of light within the visible spectrum. For skin treatment we use specific wavelengths, measured in nanometres (nm), which enter the skin at different depths and target different concerns.

The most studied wavelengths of single colour (monochromatic) light are:

• Blue (415nm), used to treat acne.
• Red (633nm), used for skin rejuvenation, wrinkle reduction, calming acne inflammation, pigmentation and rosacea, and medically in PDT for certain non melanoma skin cancers. Red light has both a rejuvenating and an anti inflammatory effect, and increases cellular energy (ATP), which boosts cell renewal.
• Near infrared (830nm), the most deeply penetrating wavelength. It works through absorption at the cell membrane to stimulate processes that increase collagen, elastin and growth factor production, helping to treat the visible signs of photodamage and supporting the repair mechanisms essential to wound healing.

A wavelength outside these well documented ranges may still give some results. But missing the target chromophore in the cell, combined with inconsistent power, could lead to photosensitivity reactions, or too much energy could actually stop the cell responding at all.

How LEDs work, and why quality matters

Light emitting diodes are small lights that produce light when an electric current passes through them. Electrons in the semiconductor recombine with electron holes and release energy as a photon. During manufacture, the materials used can fine tune the light to a pre selected peak wavelength, giving a defined spectrum of light.

Many LEDs available off the shelf are the same type used in TVs, lighting and computer screens. These are RGB LEDs, which combine red, green and blue to produce many different hues. Devices using RGB LEDs for skin are generally cheap to produce, and often use single LEDs that change colour rather than individual LEDs that each emit one colour and wavelength.

RGB LEDs can't deliver the energy needed for results (measured in joules), and their wavelength can vary by as much as 20nm either way. An inconsistent wavelength combined with variable energy could be hazardous, or simply ineffective. Blue light in particular can be harmful to the eyes over time, especially without the right eye protection.

All LED devices must state warnings based on their optical power. If a device has no eye safety warnings at all, either it doesn't conform to safety standards, or it sits at the lowest measured optical output and may not produce enough energy for significant results.

In LED skin treatment, light energy is delivered to the target chromophore to activate the cell. Poorly designed LEDs deliver energy the cells can't absorb effectively, and wasted energy can increase skin heating, which could aggravate inflammatory conditions such as acne and rosacea. Some devices also get hotter over time, which reduces their power and results, so check whether a device has cooling technology.

How close should an LED machine be to the skin?

The key to effective light therapy is how much energy the skin absorbs. The power of the LEDs determines how close the device needs to be for optimal results, and because manufacturers use different power LEDs, that distance varies from machine to machine.

Single wavelength LEDs are designed to deliver optimised intensities of light, and packing them closely together allows the maximum light and proven doses to reach the treatment area. The number of LEDs also varies between devices. More is often assumed to be better, but an even distribution of optical power is the most important factor.

Certification and markings

The market is now full of LED devices, from handheld wands with a few LEDs to masks that sit on the face and large canopy machines. With so much choice, different ways of measuring data and a lack of common standards, it can be very hard for a practitioner to compare devices fairly. Some devices have little or no clinical data, some don't conform to basic safety standards, and some could even damage the skin, so research every device before you part with your money.

A device with medical CE certification carries the CE mark together with a Notified Body number, showing it meets general safety and performance requirements. A CE mark without a Notified Body number is a basic safety mark, not a medical certification. Be wary of look alike marks on some imported devices, which can resemble the CE mark but don't mean the device has been assessed.

In Great Britain, the UK government has extended the acceptance of CE marked medical devices, so a UKCA mark isn't yet compulsory. According to GOV.UK, CE marked devices can be placed on the GB market until 2028 or 2030, depending on which EU regulation they were certified under, and a 2026 consultation has proposed recognising them indefinitely. Wherever you work, check the markings your country requires.

Some insurance companies now ask for proof of equipment certification, too.

Look for results

Buying a device without understanding the technology can lead to poor choices, potentially disastrous consequences and little or no result for the client. As we strive for the best outcomes for our clients, we must offer the very best technology we can without compromising safety.

The most important thing to consider is results, because that is why we bring these machines into our businesses in the first place. A medical device company making results based claims will have spent years and a great deal of money producing the data to support them, and will be proud to share it.

How to choose an LED phototherapy device

Due diligence is essential. It is our duty as professionals to consider all the information available, to keep our clients and ourselves safe. Skipping the research could have serious consequences, or leave clients seeing no results at all. Here are my top five things to check:

1. Clinical evidence. Ask the distributor or manufacturer for white papers, independent clinical trials and photos of results from their own device. Don't accept generic LED studies or papers about a machine that simply looks similar. PubMed is a free source of research, and doing your homework pays dividends.
2. Wavelengths. Which wavelengths are used? How are they delivered in treatment? Can you combine wavelengths, such as red and blue together, without reducing effectiveness?
3. The LEDs themselves. Are they single colour, single wavelength LEDs? If they change colour, how does the device stay effective at each wavelength, and is there data to prove it?
4. Certification. Does it have medical CE certification or FDA clearance? Does it meet safety standards and the requirements of your industry body and insurer?
5. Manufacturing and markings. Where is it made, and what markings does it carry? Check that the CE mark is genuine and, for a medical device, has a Notified Body number.

LED works beautifully alongside other skin treatments, such as microneedling and skin peels, to calm the skin and support healing. If you are a client, you can search the directory to find a qualified professional offering LED near you.