Red Light Therapy 101: Benefits, Side Effects, Risks and How to Use It

This article is for general education and isn't medical advice. Check with your doctor before starting a new therapy, especially if you have light sensitivity or an eye condition, are pregnant, or take medications that increase light sensitivity.

Red light therapy has moved from niche biohacking circles into mainstream recovery and wellness — and for good reason. As a certified personal trainer, stretch therapist, and massage therapist, I've watched the research stack up over the past several years, and I now consider red light therapy one of the most versatile recovery tools available for my clients. This guide covers what red light therapy actually does at the cellular level, the benefits backed by peer-reviewed research, the side effects and risks you should know about, and exactly how to use it.

What Is Red Light Therapy and How Does It Work?

Red light therapy — also called photobiomodulation (PBM) — uses specific wavelengths of red and near-infrared (NIR) light to stimulate cellular function. The most clinically studied wavelengths are 660nm (red) and 850nm (near-infrared), though wavelengths between 630nm and 1064nm all show therapeutic potential.

The mechanism is well-documented in peer-reviewed literature. Red and NIR photons penetrate the skin and are absorbed by cytochrome c oxidase (CCO), an enzyme in the mitochondrial electron transport chain. CCO is the primary photoacceptor — when it absorbs light energy, it dissociates inhibitory nitric oxide from the enzyme, which increases electron transport, boosts mitochondrial membrane potential, and ramps up ATP (adenosine triphosphate) production. ATP is the energy currency your cells use for repair, regeneration, and normal function.

The downstream effects include increased cellular metabolism, reduced oxidative stress, modulated inflammation, and enhanced blood flow. A small 2016 study in Scientific Reports (11 healthy adults) found that a 1064nm infrared laser applied to the forearm increased cytochrome c oxidase activity and hemoglobin oxygenation in the treated tissue compared with placebo.

Red Light Therapy Benefits Backed by Research

The clinical evidence for red light therapy spans skin health, pain management, muscle recovery, inflammation, and more. Here are the benefits with the strongest research support.

Skin Health and Collagen Production

A controlled clinical trial published in Photomedicine and Laser Surgery (Wunsch & Matuschka, 2014) enrolled 136 volunteers and treated them twice weekly for 30 sessions with filtered lamp units in the 611–650nm and 570–850nm ranges. Compared with untreated controls, treated participants showed reduced skin roughness on profilometry and increased collagen density on ultrasound, and blinded evaluators rated wrinkles as improved in 69–75% of treated participants versus 4% of controls. The study used lamp-based devices rather than LED panels, and it was funded by the device maker.

A 2025 Stanford Medicine overview quoted Stanford dermatologists describing fairly robust evidence for wrinkle reduction and hair growth, while noting that in-clinic treatments are almost always more powerful than at-home devices and that dosing for home devices is largely unknown.

Pain Relief and Joint Health

Pain is one of the most studied applications of photobiomodulation, but much of that research has used clinical low-level lasers rather than home LED panels, and the overall picture is mixed: Stanford Medicine's 2025 overview noted that results for chronic pain haven't been scientifically validated.

For joint-specific conditions, a 1992 randomized trial of 50 older adults with knee osteoarthritis found that self-applied red or infrared light (15 minutes twice a day for 10 days) reduced pain by more than 50%, while the placebo group saw no significant improvement. It was a small, older study, so treat it as encouraging rather than conclusive. If you're dealing with joint pain, I cover specific protocols in our guides on knee pain and red light therapy, hip pain and red light therapy, and wrist pain and red light therapy.

Muscle Recovery and Athletic Performance

This is where red light therapy gets especially interesting for athletes and gym-goers. A 2018 systematic review and meta-analysis of 39 trials with 861 healthy participants found low- to moderate-quality evidence that photobiomodulation (laser, LED, or both) has some beneficial effect on exercise performance and fatigue, and the authors called for better-designed studies.

Keep expectations realistic: Stanford Medicine's 2025 overview noted that evidence for athletic performance benefits is still lacking.

I recommend pairing red light therapy with other recovery tools — a session before training plus cold plunge therapy or infrared sauna post-workout creates a comprehensive recovery stack.

Wound Healing

A 2024 meta-analysis of 18 randomized controlled trials — mostly clinician-applied low-level laser therapy, many in diabetic foot ulcers — found higher rates of complete healing, greater reductions in wound size and lower pain scores compared with controls, though the authors called for higher-quality trials. These were supervised clinical treatments, not home panels, so talk to your doctor before using a device on a wound.

Inflammation Reduction

Chronic inflammation plays a role in many pain conditions and in slow recovery. A review published in the AIMS Biophysics journal detailed how photobiomodulation can modulate the NF-κB inflammatory pathway and lower pro-inflammatory cytokines in activated cells. Most of that evidence comes from cell and animal studies, and the review notes that human data are still limited.

Red Light Therapy Side Effects and Risks

One of the advantages of red light therapy is its strong safety profile compared to pharmaceuticals or more invasive treatments. That said, there are side effects and risks to be aware of.

Common side effects are mild and temporary: slight skin redness, warmth, or tightness in the treated area that typically resolves within a few hours. Some people with sensitive skin may experience temporary dryness or mild irritation. These effects are normal and usually diminish as your body adapts to treatment.

Eye safety is critical. Don't look directly into the light. The American Academy of Dermatology advises wearing the eye protection your device's directions recommend — and not substituting sunglasses for protective goggles.

Skin tone considerations: According to the American Academy of Dermatology, people with darker skin tones are more sensitive to visible light such as red light, which can lead to hyperpigmentation (dark spots). If this applies to you, the AAD recommends talking with a dermatologist before using an at-home device.

What red light therapy is NOT: It isn't ultraviolet (UV) light. Cleveland Clinic notes that, unlike the cancer-causing UV light from the sun or tanning beds, red light therapy doesn't use UV, and that it appears safe when used short-term and as directed — though its long-term safety isn't yet known.

FDA status: Many home-use red light devices are FDA-cleared, which means the FDA considers them low-risk. However, FDA clearance is not the same as FDA approval for treating specific conditions — it speaks to safety, not proven efficacy for a particular diagnosis. Device quality and output power vary significantly between manufacturers, which is why I recommend investing in clinical-grade panels from reputable brands like Therasage and Kineon.

When to avoid red light therapy: Consult your doctor before starting if you're pregnant, taking photosensitizing medications, have active cancer, or have a history of eye conditions. While research hasn't shown harm in these populations, there isn't enough data to confirm safety either.

How to Use Red Light Therapy: Dosage and Protocol

Getting the dosage right matters more than most people realize. Too little light produces no therapeutic effect; too much can actually inhibit cellular function (a phenomenon called the biphasic dose response). Here are general starting points.

Dosage basics: Dose is measured in joules per square centimeter (J/cm²). The formula is simple: Dose = Power Density (mW/cm²) × Time (seconds) × 0.001. There's no single agreed dose for home devices — Stanford dermatologists note that dosing is largely unknown for at-home tools — so treat the ranges below as general starting points and follow your device's instructions.

Frequency: Start with 3–5 sessions per week for the first 4–8 weeks. Once you've established a baseline response, many people maintain results with 3–4 sessions per week.

Distance: Follow your device manufacturer's recommendations, but as a general rule, position the panel 6–12 inches from the treatment area. Irradiance drops as you move farther from the panel, so distance matters more than most users realize.

Timing relative to exercise: Research on the best timing around exercise is still limited, so follow your device manufacturer's guidance. Avoid combining with ice or cold therapy simultaneously — use them sequentially for best results.

Red Light Therapy vs Other Wavelengths

Not all light therapy is the same, and the differences between LED and laser delivery, as well as between red and near-infrared wavelengths, matter for treatment selection. Red light (630–660nm) is mainly used for surface-level goals like skin health. Near-infrared light (810–850nm) penetrates deeper — light-tissue modelling shows penetration depth increases with wavelength — which is why it's typically chosen when the target is muscle or joints rather than skin. For a detailed breakdown, see our guide on LED vs laser light therapy.

Build Your Red Light Therapy Setup

If you're ready to add red light therapy to your recovery routine, the key is choosing a device that delivers clinical-grade power output at the right wavelengths. Panel-style devices offer the best coverage for large treatment areas like the back, legs, or full torso. Targeted devices and mats work well for joints and localized treatment.

At Peak Flow Fitness, we carry professional-grade red light therapy devices from brands like Therasage and Kineon, including red light panels for full-body sessions and red light mats for targeted therapy. Browse our full red light therapy collection to compare devices and find the right fit for your recovery needs.

Related reading: LED vs Laser Light Therapy · Knee Pain and Red Light Therapy · Herniated Disc and Red Light Therapy · Red Light Therapy for Fertility