Red light therapy refers to the therapeutic application of red and infrared light wavelengths to assist with the treatment of various skin conditions and/or health conditions of the body. Because red light therapy has been used for many different ailments and across different industries, there are multiple names used to describe red light therapy, such as LLLT (low level laser therapy), PBM (photobiomodulation), cold laser therapy, and in the case of skin treatments, simply “red LED.”

Red light therapy includes a wide range within the red light spectrum. Although Red light therapy may vary due to differences in their energy output, in general wavelengths in the range of 390 nm to 600 nm are used to treat superficial tissue, and longer wavelengths in the range of 600nm to 1,100nm, which penetrate further, are used to treat deeper-seated tissues.⁵

Red light therapy may be administered by placing a panel of lights close to the area to be treated, as is the case in applications of red light therapy for the skin. Alternatively, low level laser therapy or LLLT photobiomodulation is not within a visible light range and professional devices generally employ a handpiece that emits a laser-like beam of visible light at the target area to direct the invisible LLLT light energy. Applications of red light therapy are not painful, do not produce excessive heat, and require no downtime.

There is not currently evidence that red light therapy damages cellular DNA or induces cancerous cell growth. In fact, some preliminary studies suggest the use of red light therapy may inhibit melanoma, but further studies are needed.⁶ However, photobiomodulation does have an effect on cellular activity and proliferation, and, for this reason, it is not performed on patients with active cancer, although it may be used to alleviate some symptoms of cancer treatment such as oral mucositis, or tissue swelling in the mouth.

Red light therapy is a wonderful addition to nearly anyone’s skin care regimen because it produces a spectrum of favorable results with zero downtime and a very low probability of adverse effects. However, in lieu of augmenting positive results, overuse of red light therapy may actually lead to tissue damage. What might constitute “overuse” is determined by the wavelengths and energy output of the light. This explains why red light therapy devices may differ in their recommendations for frequency and duration of use. It’s best to follow the instructions of an experienced practitioner or of a specific device to achieve optimal photobiomodulation results.

Although red light therapy is considered safe, researchers are not exactly certain how or why red light therapy benefits the skin or body. It is known that a certain level of light energy must be delivered to specific layers of the skin to achieve different outcomes, but not every red light therapy device is designed to address the same conditions or work under the same energy output. Therefore, there are no set rules on how long and how often red light therapy or low level laser therapy should be used. For the best results with photobiomodulation, it’s best to follow the recommendation of a healthcare provider, or, in the cases of an at-home device, the manufacturer's guidelines for red light therapy.

Red light therapy may potentially address multiple factors that influence the appearance of the skin. The light emitted by a photobiomodulation device is absorbed by the mitochondria in the skin cells, helping them to create more adenosine triphosphate (ATP), which is the main energy source for cells. This boost in energy spurs more activity on the cellular level which can lead to an increase in collagen and elastin production as well as activating multiple other cellular functions, such as DNA repair. The combination of these effects accounts for the frequent patient report of firmer or “tightened” skin after red light therapy, although it may take several treatments to achieve these visible results. However, red light therapy does not deliver the level of thermal heat necessary to cause contraction of existing collagen fibers, as is seen in stronger modalities using radiofrequency or ultrasound. The tightening effect from red light therapy is due to healthier skin and increased collagen and elastin production.⁷

Those who suffer from acne may know the frustration of being told to avoid the sun, while noticing that sun exposure improves their acne. The reason is that light can alter the way the sebaceous glands behave, by slowing overactive oil-production. But, of course, that benefit comes with the damaging effects of UVA and UVB exposure. Thankfully, photobiomodulation offers multiple approaches for improving acne, and red light therapy is often combined with blue LED for significant improvement in inflamed acne without side effects.⁸ Even at-home photobiomodulation devices blending or alternating between blue and red LED lights have been shown to improve acneic conditions.

Low level laser therapy (LLT) has been cleared for a variety of treatment options since the late 1980s when the FDA first began to regulate medical devices. Since then the number of FDA-cleared LLT devices on the market has steadily grown with clearances for the treatment of various pain and dermatologic conditions. Much of the use of LLLT is for whole-body pain, but it is also an approved device for skin healing and skin discorders that benefit from inflammation reduction such as psoriasis and eczema. Since the first red light therapy device in the US was developed in the 1960s, the market has continued to grow with recent reports citing red light therapy as the “most widely preferred treatment for multiple ailments”. To verify the FDA clearance and therapeutic claims of a particular photobiomodulation device, it’s recommended to consult the “medical devices” database on the FDA website.

In general, devices for red light therapy and low level laser therapy (LLT) are low-risk devices cleared for sale by the FDA. This does not mean that the claims made by manufacturers of said devices have been verified by clinical studies or approved by the FDA.

To date, studies show no adverse events from low level laser therapy.⁹ However, red light therapy is generally not performed in cases of pregnancy, epilepsy, active thyroid conditions, and if the patient takes medications that increase light sensitivity. For most patients, receiving LLT treatment from a knowledgeable clinician or following the guidelines of use of an at-home photobiomodulation device should present no safety issues or negative side effects besides mild erythema.