What Is Red Light Therapy? The Complete Guide to How It Works and What It Can Do

Red light therapy (RLT) is a non-invasive form of photobiomodulation (PBM) that uses specific wavelengths of red and near-infrared light to stimulate cellular function. It can be delivered using LEDs or low-power lasers, also known as low-level laser therapy (LLLT), and is commonly used to support skin health, muscle recovery, pain management, wound healing, and hair growth.

Researchers believe these benefits occur because red and near-infrared light interact with light-sensitive components inside cells, helping support cellular energy production and other biological processes involved in repair and recovery. Unlike ultraviolet (UV) light from the sun, which can damage the skin, therapeutic red and near-infrared wavelengths are designed to trigger beneficial cellular responses without causing harm to healthy tissue.

Although red light therapy is often discussed in terms of its benefits, how it works is just as important. Factors such as wavelength, irradiance, treatment frequency, and dose can all influence treatment outcomes. Understanding the science behind photobiomodulation can help explain why different red light therapy devices are designed the way they are, what results to realistically expect, and how to get the most from treatment.

Red Light Therapy: The Basics

Red light therapy is part of a broader category of treatments known as photobiomodulation (PBM), which refers to the use of light to influence biological processes within the body. While the terms are often used interchangeably, photobiomodulation is the scientific umbrella term, while red light therapy typically refers to treatments that use red and near-infrared wavelengths.

Although red light therapy has become increasingly popular in recent years, the technology itself is not new. Researchers have been studying the effects of therapeutic light since the 1960s, when early experiments suggested that certain wavelengths could support wound healing and tissue repair. Over the following decades, research expanded into areas such as inflammation, chronic pain, muscle recovery, skin health, hair growth, and circulation.

Today, photobiomodulation treatments may be delivered using either lasers or LEDs, depending on the device and intended application. Both technologies are capable of delivering therapeutic wavelengths, but they differ in how light is delivered to the body. 

How Does Red Light Therapy Work?

Red light therapy works by delivering specific wavelengths of red and near-infrared light that are absorbed by cells and converted into biological signals. These wavelengths can be delivered using either LEDs or lasers, and while both approaches aim to stimulate photobiomodulation, factors such as wavelength, irradiance, treatment dose, and device design may influence how much light reaches the target tissue and how cells respond.

The process can be broken down into three key steps: first, cells absorb the light; next, that absorbed light influences cellular energy production and signaling pathways; and finally, those cellular changes may help support processes involved in healing, recovery, and overall tissue health.

1. Light Energy Is Absorbed by Your Cells

For red light therapy to have an effect, the light must first be absorbed by the body. This occurs through light-sensitive molecules called chromophores, which absorb specific wavelengths of light and help trigger biological responses inside cells. One of the most studied chromophores in photobiomodulation is cytochrome c oxidase, an enzyme found within the mitochondria. Multiple reviews of photobiomodulation literature have identified cytochrome c oxidase as a primary target of red and near-infrared light and a key driver of the cellular responses associated with treatment.

Chromophores act like tiny light receptors. When they absorb therapeutic wavelengths of red and near-infrared light, they initiate a chain of cellular events that ultimately drive many of the biological effects associated with photobiomodulation.

2. The Absorbed Light Increases Cellular Energy and Signaling

Once chromophores absorb red and near-infrared light, they can influence activity within the mitochondria (often referred to as the “powerhouses” of the cell). Mitochondria produce adenosine triphosphate (ATP), the primary source of energy that cells use to function. ATP powers countless cellular processes, including repair, growth, communication, and recovery. Because nearly every cell in the body relies on ATP to function, researchers believe that supporting cellular energy production may help explain many of the biological effects associated with red light therapy.

The increase in cellular energy also appears to trigger a variety of signaling pathways throughout the body. According to research on the mechanisms of photobiomodulation, light absorption can influence nitric oxide, reactive oxygen species (ROS), calcium signaling, and other cellular messengers that help regulate how cells communicate and respond to their environment. Researchers believe these signaling changes help translate light absorption into broader biological effects throughout the body.

3. These Cellular Changes May Support Healing and Recovery

The cellular changes triggered by red light therapy may influence several biological processes associated with healing, recovery, and overall tissue health. Research suggests photobiomodulation can help support healthy blood circulation, regulate inflammatory pathways, and influence cellular processes involved in tissue repair.

For example, increased nitric oxide availability may help support blood flow by encouraging blood vessels to relax and widen. Researchers have also observed effects on inflammatory signaling and oxidative stress, which may help explain why red light therapy is commonly studied for applications involving recovery and inflammation.

These mechanisms may also influence processes involved in collagen production, wound healing, muscle recovery, and other aspects of cellular repair. While the specific effects vary depending on the tissue being treated, many of the proposed benefits of red light therapy can be traced back to these underlying biological responses.

Red Light Therapy Wavelengths

Red light therapy uses specific wavelengths of red light, typically ranging from about 600 nm to 660 nm. However, many modern photobiomodulation devices also incorporate near-infrared (NIR) light, which falls just beyond the visible red spectrum and typically ranges from about 800 nm to 870 nm. Although red and near-infrared light are distinct wavelengths, they are often used together because each reaches different depths within the body. Red light is generally absorbed closer to the skin's surface, while near-infrared light can penetrate deeper into underlying tissues.

The difference in penetration depth is supported by a computational study examining light-tissue interactions, which shows that penetration depth generally increases as wavelength increases. This helps explain why near-infrared wavelengths are often used when targeting structures below the skin’s surface. Together, red and near-infrared light allow photobiomodulation devices to deliver light energy across multiple tissue layers.

What Is Red Light Therapy Used For?

Red light therapy has been studied for a wide range of health and wellness benefits, including skin health, hair growth, oral health, muscle recovery, pain management, wound healing, and inflammation support. While the specific effects may vary depending on the tissue being treated and the wavelengths used, many of these applications are rooted in the same underlying mechanisms discussed above: supporting cellular energy production, cellular signaling, circulation, and tissue repair.

Research is ongoing, and not every application is supported by the same level of evidence. However, the following are among the most common uses of red light therapy today.

Skin Health and Signs of Aging

Skin health is one of the most studied applications of red light therapy. Research suggests that red and near-infrared light may support collagen production, tissue repair, and cellular renewal, making photobiomodulation a popular addition to many skincare routines.

Red light therapy has been studied for a variety of skin-related concerns, including fine lines and wrinkles, uneven skin tone, age spots, acne, scars and stretch marks, wound healing, rosacea, psoriasis, and eczema. A 2024 review examining photobiomodulation in dermatology highlighted its potential role in supporting skin health through its effects on cellular function and signaling pathways.

While results vary depending on the individual and the condition being treated, skin-focused applications remain among the most researched and widely used areas of photobiomodulation.

Muscle Recovery, Pain Relief, and Inflammation Support

Red light therapy is also commonly used to support muscle recovery, pain management, and healthy inflammatory responses. Researchers have studied photobiomodulation for a variety of recovery-related applications, including exercise recovery, muscle soreness, joint discomfort, and chronic pain.

Research suggests that red and near-infrared light may influence biological processes involved in circulation, tissue repair, and inflammation regulation. A review on the anti-inflammatory effects of photobiomodulation found that red and near-infrared light can influence inflammatory pathways and reduce markers associated with inflammation in a variety of tissues.

These effects help explain why red light therapy has become increasingly popular among athletes, active individuals, and people seeking non-invasive ways to support recovery and physical wellness.

Oral Health and Gum Support

Oral health is a popular area of photobiomodulation research. Researchers have studied red and near-infrared light for applications related to gum health, oral inflammation, tissue healing, and overall oral wellness. Because the mouth contains highly vascular tissues that regularly undergo repair and regeneration, scientists have become increasingly interested in how photobiomodulation may support these natural processes.

Research suggests red light therapy may help support healthy inflammatory responses, circulation, and cellular activity within oral tissues. Studies have investigated its use alongside routine oral hygiene practices and professional dental care for a variety of applications, including gum health and oral tissue recovery. While research is ongoing, oral care has become one of the fastest-growing consumer applications of photobiomodulation.

Hair Growth and Hair Health

Hair growth is another area where red light therapy has received significant research attention. Researchers have studied photobiomodulation for hair thinning and certain forms of hair loss, particularly those involving changes in hair follicle function and growth cycles.

While the exact mechanisms are still being investigated, research suggests that red and near-infrared light may help support cellular activity within hair follicles and promote conditions that encourage healthy hair growth. For this reason, red light therapy is commonly incorporated into specialized devices such as caps and helmets designed for scalp treatments.

As a result, hair growth has become one of the more popular consumer applications of red light therapy, alongside skin health and recovery support.

Emerging Areas of Research

Beyond skin health, recovery support, and hair growth, researchers continue to explore the potential of photobiomodulation in a variety of other fields. Ongoing studies are investigating applications related to cognitive and neurological health, metabolic health and weight loss, sleep quality, women’s health, and gut health, among others.

While some early findings are promising, many of these applications require additional research before firm conclusions can be drawn. As the science continues to evolve, researchers are working to better understand where red light therapy may offer the greatest benefits and which treatment protocols are most effective.

Red Light Therapy Best Practices

Getting the most from red light therapy often comes down to three factors: using an appropriate device, following a consistent treatment schedule, and maintaining realistic expectations about results. While treatment protocols vary depending on the device and treatment goal, a few best practices apply to most red light therapy routines.

1. Follow Your Device’s Instructions

Treatment distance, session length, and frequency can vary significantly between devices. Factors such as wavelength, irradiance, and overall device design influence how much light reaches the target tissue, which is why manufacturer recommendations should always be followed.

2. Be Consistent

Red light therapy is generally most effective when used regularly over time rather than sporadically. Many people incorporate treatments into an existing routine, such as after exercise, during their skincare regimen, or as part of a recovery protocol. If you’re unsure how often to use red light therapy, we’ve put together a more detailed guide on creating an effective treatment schedule.

3. More Is Not Always Better

Photobiomodulation appears to follow a biphasic dose response, meaning there is likely an optimal treatment range. Too little light may not produce meaningful effects, while excessive exposure may reduce the desired biological response. Following recommended treatment guidelines is typically more effective than simply increasing session length or frequency.

4. Choose a Quality Device

When comparing devices, factors such as wavelength, irradiance (the amount of light energy delivered), and overall device design can influence treatment effectiveness. Both LED and laser-based devices can support photobiomodulation, but lasers often deliver a more concentrated dose in less time, while LEDs typically cover a larger treatment area. When comparing devices, look for manufacturers that clearly disclose specifications such as wavelengths, irradiance, and treatment recommendations.

5. Set Realistic Expectations

Some applications of red light therapy may produce noticeable changes within a few weeks, while others can require several months of consistent use. Results vary based on the condition being treated, the device being used, and individual biological factors. For a more detailed breakdown of what results to expect and when, see our guide on how long red light therapy takes to work.

Is Red Light Therapy Safe?

Red light therapy is generally considered safe and well-tolerated when used according to the manufacturer’s instructions. In fact, one reason photobiomodulation has gained popularity is that it’s a non-invasive treatment that doesn’t involve drugs, injections, or surgery.

Side effects are typically mild and uncommon but may include temporary redness, warmth, irritation, or eye discomfort if proper eye protection is not used when recommended. Following the manufacturer’s guidelines for treatment distance, frequency, and session length can help reduce the risk of unwanted effects.

You should speak with a healthcare provider before using red light therapy if you:

• Are pregnant or breastfeeding

• Have a history of skin cancer

• Have a medical condition that causes light sensitivity

• Take medications that increase sensitivity to light

• Are receiving treatment for a serious medical condition

As with any wellness or therapeutic modality, red light therapy should be viewed as a complement to — not a replacement for — appropriate medical care.

The Growing Appeal of Red Light Therapy

Red light therapy is a non-invasive treatment that uses specific wavelengths of red and near-infrared light to support cellular energy production and influence biological processes involved in recovery, repair, and overall tissue health. While researchers continue to explore new applications for photobiomodulation, existing research has already investigated its potential role in areas such as skin health, hair growth, muscle recovery, pain management, and inflammation support.

One of the biggest advantages of red light therapy is its versatility. Whether you’re looking to support a skincare routine, improve post-workout recovery, promote healthy hair growth, or simply incorporate a science-backed wellness tool into your daily routine, red light therapy offers a convenient way to bring the benefits of photobiomodulation into your home.

Novaalab offers a wide range of red light therapy devices designed to support everything from recovery and pain relief to skincare and oral health. With clinically relevant wavelengths, transparent device specifications, at-home convenience, and a growing lineup of products, Novaalab makes it easy to find a solution that fits your goals and lifestyle.