Red Light Therapy: The Science Behind The Light + Benefits, Side Effects + FAQ

Plenty of esthetic treatments come with a pamphlet packed with side effects and strict post-treatment protocols (like chemical peels, for example). But what if there were treatments that got right to the point and started healing the skin ASAP—wouldn't that be nice? 

Luckily, there are—and one of them is red light therapy. You may have seen these high-tech masks on the shelves at beauty stores, but these devices are more than just a flashy item to add to your routine—here's the science behind the light.

Red light therapy—also known as red LED light therapy, low-level light therapy (LLLT), photobiomodulation, and cold laser therapy—involves exposing the skin to red and near-infrared light between the wavelengths of 660 nm and 890 nm with either low-level lasers or red LED lights. And they're thought to be absorbed by skin up to 10 millimeters.

LED light therapy comes in all shapes and sizes, too. You may find them in handheld wands, face masks, desk lamps, or even full-body beds.

At this point you may be wondering: Isn't light bad for the skin? Isn't that why we're always told to avoid UV rays? Rest assured: These specific wavelengths do not burn or damage the skin (unlike the dangerous UVA/UVB rays from the sun or in tanning beds).

Red light works via a phenomenon called photobiomodulation. "This is where different components of our cells are activated or respond to different wavelengths of light," board-certified dermatologist Erum Ilyas, M.D., MBE, FAAD, tells mbg.

The exact mechanisms of photobiomodulation are not completely understood, but the effects have been clinically studied1. "Studies seem to show that light acts on the mitochondria of cells, which leads to increased production of different factors that increase the proteins and factors that allow cells to communicate," Ilyas explains.

By allowing the cells to communicate, red light therapy essentially helps your skin work more effectively. "This may help stimulate collagen production and other factors that help with skin remodeling," Illyas says.

The activation of these mitochondria also appears to stimulate the production of growth factors and reduce oxidative stress in the skin—both things that can improve the health of the skin2, according to board-certified dermatologist Apple Bodemer, M.D. She goes onto explain that these also have anti-inflammatory benefits3.

And one of the easiest ways to explain how red light (RLT) and other low-level light therapies work is to compare it to other traditional skin care devices like lasers and intense pulsed light (IPL). 

"Lasers traditionally work by causing controlled damage in the skin in an attempt to trigger an inflammatory reaction," she notes. This can result in positive changes such as wrinkle reduction, improved hyperpigmentation, or reduced redness, Ilyas says.

"Red light therapies and other LLLTs are different in that they are atraumatic to the skin," she says. Meaning that instead of creating microtraumas that trigger healing, they start to positively impact the skin right away. Pretty cool, right?

The best part? "The effects are seen without the discomfort, healing time, and possible reactive swelling that are seen with traditional laser and IPL platforms," she notes. Translation: You're tending to the skin on a cellular level without a bunch of negative side effects—more on that in a bit.

"A brighter and more radiant complexion is achieved after just one session. But completing multiple sessions will yield greater results over time," master esthetician Sarah Akram once told mbg.

How long red light therapy takes to yield the results you're after will differ greatly depending on how consistently you receive red light therapy, the tools used, and of course, the results you're after. But you should be seeing more dramatic results after a few weeks to a month.

"Those with acne-prone, sensitive, and reactive skin can also benefit from the red light since it's helping to promote overall skin health," Ross says. While it may be assumed that a higher wavelength of light would be more effective for treating acne, the opposite has been demonstrated.

In one study, patients with mild to moderate acne received red light therapy in two different wavelengths on either side of their face—630 nm on the right, 890 nm on the left—and only the lower wavelength significantly reduced acne lesions4.

In many studies, red light has been combined with blue light for acne treatment, as blue light can also provide antibacterial effects—which is much needed for many people struggling with breakouts.

In one 2017 study in the Journal of the American Academy of Dermatology5, low-level blue and red light therapy was shown to be both well tolerated and effective at reducing the total count of acne lesions6 over the 12-week study compared with the baseline.

To sum up, red light therapy—especially when used in combination with blue light therapy—has been proved effective at reducing breakouts.

One 2017 research review7 suggested that red light therapy can help improve the appearance of plaque psoriasis. The participants in the study were sequentially treated in two 20-minute sessions for four or five weeks.  Just over half of the participants needed a second round, but the results were impressive.  The authors reported : "Sixty to 100% of clearance rates8 were achieved without any significant side effects."

"There are some studies evaluating the use of red light therapy for increasing collagen and potentially elastin production as well with a demonstrable increase in collagen density," Ilyas notes.

One study found that patients receiving red light therapy on their face twice a week for 30 total sessions experienced improved skin complexion9, skin tone, skin smoothness, and collagen density (as measured with an ultrasonographic test).

In fact, the study included some before-and-after pictures9, which are pretty impressive. A possible explanation for the role of red light therapy on collagen production is because of the photobiomodulation mechanism. "This means that the light stimulates different pathways in cells that can trigger different outcomes," Ilyas explains.

"Some theories suggest that red light therapy may reduce damaged collagen in the skin from traumatic injury or UV damage altering the balance to make way for new collagen production to occur," she continues.

All in all, studies have demonstrated that red light therapy can improve collagen density, which leads to fewer fine lines and wrinkles and tighter skin, among other benefits.

Increased collagen production is great for skin aging but not so much for scar formation. Take keloid scars for example—the scar continues to grow even after the wound is healed, due to too much collagen production on the site of the scar.

Luckily, red light therapy actually helps to regulate collagen production, meaning it can help to slow down collagen production when there's an overload, too. It's pretty much the best of both worlds.

"Red light therapy is used for and studied for its ability to reduce collagen production in scar tissue and wound formation," Ilya notes. "A review of the medical literature10 shows that red light therapy has several potential mechanisms for down-regulating collagen production," she continues.

Altogether, scars can become thicker when too much collagen is produced on the scar site. Red light therapy can help regulate collagen production, so your body is making the right amount of collagen for the right areas. Essentially it can increase it in areas where collagen has been damaged, and also decrease it in scars and thus preventing them from getting too thick, notes Bodemer.

The same study that demonstrated promise for red light therapy in healthy skin aging also showed an improvement in skin tone and texture9. These benefits may come from red light therapy's ability to encourage effective cellular function in the skin.

"Perhaps the most notable benefit of red light therapy in studies is the improved quality and texture of the skin," Ilyas states. "Reducing redness and inflammation of the skin can help those affected by acne, sun damage, and wound healing," she continues.

To sum up, if you're not looking to reduce breakouts or regulate collagen production, red light therapy can improve the look and feel of the skin by targeting tone and texture.

Apart from the many skin health and esthetic benefits, red light therapy can impact the body as well. Some common benefits are, put simply, not totally backed by science yet. Others, however, have shown some promise in research. Here's what we know.

Let's debunk this common LED myth: Red light therapy cannot reduce body fat. "Red light therapy, especially at-home devices, probably cannot penetrate deep enough in the skin to have an impact," Ilyas says.

"Although red light will not help with body fat alone, it is helping the body to perform at its best, and when combined with diet and exercise, there can be a minor benefit," Ross mentions.

As mentioned earlier, red light therapy can regulate collagen production, leading to tighter skin. "With the potential for increased collagen and elastin, there is the potential to improve the overall quality of aging skin and reduce laxity," Ilyas explains.

If you're looking to tighten crepey skin, red light may be one approach. But the tools used for the face and body may be different—more on that in a bit.

Research conducted by NASA has found that red light therapy helps counter a side effect of chemotherapy called oral mucositis, characterized by extremely painful sores, redness, dryness, and burning sensations in the mouth and throat.

A two-year trial in which cancer patients were given a far-red and near-infrared LED treatment determined that 96% of patients experienced reduced pain as a result of this treatment. This is great news since it could help increase food intake, reduce use of painkillers, and boost morale among cancer patients.

The difference between in-office and at-home red light therapy treatments is largely the range in wavelength and how deeply those waves can penetrate into the skin. In-office devices can penetrate deeper than at-home devices, Ilyas says.

To be more specific, medical-grade devices can penetrate about 6 millimeters in depth, while at-home devices has much more variability in what it can penetrate.

One perk of receiving in-office treatments is the combination approach. "In-office, red LED therapy may often be coupled with other modalities to improve efficacy," Ilyas explains. Some of these modalities include microneedling or photosensitizers (like aminolevulinic acid, for example). 

This combination method helps to increase the absorption of the light to gain more benefit, Ilyas says. Which therapy is used in combination with the red light will depend on the skin conditions present and the goals of the patient.

Red light therapy can be done in a medical office or by a trained esthetician, such as during a LED facial. When red light therapy is used on its own, there's typically no downtime after treatment. However if used in combination with an invasive treatment, like microneedling for example, that's another story.

There are a few things to keep in mind for pre- and post-LED facial care, especially when it comes to topical products. "I would advise to refrain from any aggressive exfoliant products or sun exposure prior to LED light therapy skin treatment," esthetician Aneta Zuraw, co-founder of Atelier Beauté once told mbg.

Be sure to ask your esthetician or medical professional for exact pre- and post-care to ensure you're reaping all of the possible benefits.

While medical-grade red light therapy devices may be able to penetrate deeper into the skin, these treatments can get pricey. Luckily, there's a plethora of at-home devices to choose from that will obviously include a one-time payment (which, yes, can also be expensive), but will provide lasting access to red light treatment.

"Devices that provide closer access to the light through well-fitted masks that can stay on for a window of time will have a higher potential of gaining some benefit," Ilyas says. "Devices that rely on flat screens of lights or wands may require the user to take into consideration the distance from the light and time allotted in each area," she continues.

As mentioned above, in-office treatments can combine both red and blue light for even more benefits. Luckily, there are at-home tools available that have both too—such as the one created by Ross, the Trilogy Wand. ("It combines multiple therapies including both red and blue LED, warming massage, cryotherapy, along with lymphatic drainage," Ross notes. He recommends using the wand up to three times a week—but how often you use another at-home device may differ.)

As we noted above, there's a wide range of devices available: from wands to masks to lamps. But not all of them are created equal, so it's important to do your research before investing. Here's our list of the best at-home devices to kick off your search right.

It's important to note that these devices and office treatments can be pricey. If you're not ready to buy a red light therapy device, don't worry—there are plenty of other ways to treat acne, encourage collagen production, smooth texture, and improve the appearance of scars at home that are budget-friendly and more accessible.

So, are there any negative side effects of red light therapy? "Studies11 demonstrate that red light therapy is effective on all skin types; however, it may require dose adjustment to decrease the potential for adverse effects including hyperpigmentation," Ilyas notes.

If you get an in-office treatment, be sure to chat with your expert about the side effects of the specific device they're using and any concerns you have. If you opt for an at-home device, start slow by using the tool once or twice a week, and keep an eye on how your skin reacts. If you notice anything unusual, consult your dermatologist.

Red light therapy devices have the power to start encouraging better skin function from the start. You can use red light therapy both through in-office treatments and at-home devices. There's a long list of benefits for inflammatory skin conditions, collagen production, and more. If you're ready to invest, check out our curated list of the best devices on the market.

04/14/23: We got this story medically reviewed by a board-certified dermatologist, and added more context to studies where it was relevent.