What infrared light therapy does in your body

Infrared light therapy uses wavelengths of light (typically 700 to 1100 nanometers) that penetrate deeper into skin and tissue than visible light. The mechanism is straightforward: infrared photons are absorbed by mitochondria—the energy-producing structures inside your cells—where they interact with an enzyme called cytochrome c oxidase. This interaction increases the production of ATP, the molecule cells use as fuel. The theory is that more cellular energy leads to reduced inflammation, faster tissue repair, and less pain.

The depth of penetration matters. Infrared wavelengths can reach muscle, bone, and connective tissue beneath the skin surface, whereas visible red light stops in the upper layers. This is why infrared therapy is often used for joint pain, muscle soreness, and wound healing rather than skin-surface conditions. The effect is local—the light works on the tissue it reaches, not systemically throughout your body.

Devices range from small handheld panels and wraps to full-body light beds. Some combine red and infrared wavelengths; others use infrared alone. The dose—measured in joules per square centimeter—varies widely between devices and treatment protocols, which matters because too little light produces no effect and too much may reduce benefit.

Key Takeaways

  • Infrared light increases ATP production in cells by interacting with mitochondrial enzymes, which is the proposed mechanism behind reduced pain and faster healing.
  • Human trials show modest benefit for muscle soreness, joint pain, and wound healing, but effect sizes are often small and results vary between individuals.
  • Most evidence comes from short-term studies (weeks to a few months); long-term safety and durability of benefit are not well established.
  • Infrared therapy appears safe with minimal side effects, but it is not a replacement for medical treatment of serious injury or chronic disease.

Evidence from human studies on pain and soreness

The strongest human evidence exists for delayed-onset muscle soreness (DOMS)—the ache that appears 24 to 72 hours after intense exercise. Several randomized controlled trials have found that infrared light applied before or shortly after exercise reduces soreness and speeds recovery of strength. A 2015 trial published in Photomedicine and Laser Surgery found that athletes treated with infrared light reported less soreness and regained muscle function faster than controls. However, the effect was modest—not a complete elimination of soreness, but a measurable reduction.

For chronic joint pain, the evidence is mixed. Studies on knee osteoarthritis, shoulder pain, and lower back pain show some benefit compared to sham (fake) light, but the improvements are often small and inconsistent across trials. A 2019 systematic review in Lasers in Medical Science concluded that infrared light reduced pain in musculoskeletal conditions, but noted that study quality was often poor and publication bias (the tendency to publish positive results) may inflate the apparent effect. Most trials lasted 4 to 12 weeks; whether benefit persists after treatment stops is unclear.

Importantly, these studies measure pain reduction on rating scales, not functional recovery. A person might report less pain but still have the same range of motion or strength. The clinical significance of a small pain reduction is debatable—it may matter to an athlete training hard but be negligible for someone with mild discomfort.

Wound healing and tissue repair

Infrared light shows promise in accelerating wound closure and reducing inflammation in healing tissue. Animal studies consistently demonstrate faster epithelialization (skin regrowth) and increased collagen deposition when wounds are treated with infrared light. Human trials are fewer but generally supportive: studies on surgical wounds, diabetic ulcers, and burn injuries report faster healing and reduced infection rates with infrared therapy compared to standard care alone.

The mechanism appears to involve both increased ATP production and upregulation of growth factors—signaling molecules that recruit immune cells and fibroblasts (collagen-producing cells) to the wound site. Infrared light also reduces oxidative stress, which can impair healing. However, most human wound trials are small (20 to 50 participants) and conducted in specialized settings like hospitals or wound clinics. Whether the effect translates to home use with consumer devices is not established.

One limitation: infrared light works best on wounds that are actively healing. It does not appear to restart healing in chronic, stalled wounds, and it cannot replace debridement (removal of dead tissue) or infection control if those are needed.

What remains uncertain or unsupported

Several claims about infrared therapy lack solid human evidence. Systemic anti-inflammatory effects—the idea that infrared light reduces inflammation throughout the body—rest mainly on animal studies and mechanistic reasoning. No large human trials have measured inflammatory markers (like C-reactive protein) after infrared therapy. Claims about improved circulation, detoxification, or immune function are largely speculative.

The durability of benefit is also unclear. Most trials treat participants for 2 to 12 weeks and measure outcomes at the end of treatment. What happens after therapy stops? Do effects persist, fade gradually, or disappear? Few studies follow participants beyond the treatment period, so the long-term value is unknown.

Infrared therapy is sometimes marketed for conditions with no supporting evidence—depression, cognitive decline, autoimmune disease. While the cellular mechanism (increased ATP) is real, jumping from that to clinical benefit in complex systemic diseases requires human trial evidence, which does not yet exist for most of these claims.

Safety and side effects

Infrared light therapy has a good safety record in published trials. Reported side effects are rare and mild: occasional skin redness or warmth at the treatment site, and very rarely, headache or eye discomfort if the light is directed at the face. No serious adverse events have been documented in the literature, even in studies lasting several months.

However, safety data come mainly from short-term use in research settings. Long-term safety—what happens with years of regular use—has not been systematically studied. People with photosensitivity disorders, those taking photosensitizing medications, or those with a history of skin cancer should discuss infrared therapy with a doctor before use. Infrared light can generate heat, so it should not be used over areas with impaired sensation (like diabetic neuropathy) where a person might not notice burns.

Infrared therapy is not a substitute for medical diagnosis or treatment. If pain or a wound is severe, worsening, or accompanied by signs of infection, medical evaluation is necessary.

How device type and dose affect results

Not all infrared devices are equivalent. Handheld panels, wraps, and full-body beds differ in wavelength, power output, and treatment area. Wavelengths between 800 and 1000 nanometers penetrate deepest; shorter infrared wavelengths (700–800 nm) penetrate less. Power output (measured in milliwatts per square centimeter) determines how much energy reaches the tissue; higher power can deliver the same dose in less time, but there is a ceiling—too much power may reduce benefit or cause discomfort.

Most effective trials used doses between 1 and 6 joules per square centimeter, delivered over 10 to 30 minutes. Consumer devices vary widely in their actual output; some marketed as "infrared therapy" deliver very little energy. Without independent testing or clear labeling of wavelength and power, it is difficult to know whether a home device will produce the effects seen in research.

Frequency of treatment also varies. Some studies used daily sessions; others used 2 to 3 times per week. There is no established optimal schedule, and more frequent treatment does not necessarily mean better results.

Comparing infrared therapy to other light-based approaches

Infrared therapy sits within a broader category of light-based treatments. Red light therapy (600–700 nm) works through similar mechanisms but penetrates less deeply, making it better suited to skin conditions. Near-infrared light (700–1100 nm) penetrates deeper and is preferred for muscle and joint pain. Some devices combine both wavelengths.

Other light therapies—like photobiomodulation with different wavelengths, or light therapy for seasonal mood disorders—operate on different principles and have different evidence bases. Infrared therapy should not be confused with these other modalities. Within the infrared category, the evidence is strongest for acute muscle soreness and wound healing; evidence for chronic pain and systemic effects is weaker.

Frequently Asked Questions

Does infrared light therapy work for arthritis?

Some trials show modest pain reduction in osteoarthritis, particularly in the knee, but the effect is small and inconsistent. Infrared therapy may reduce pain enough to improve function during physical therapy, but it is not a cure and should not replace medical management of arthritis. Results vary widely between individuals.

How long does it take to see results?

For muscle soreness, some benefit appears within days to a week. For chronic pain or wound healing, changes typically take 2 to 4 weeks of regular treatment. Some people see no benefit at all. If no improvement occurs after 4 weeks of consistent use, further treatment is unlikely to help.

Can I use infrared therapy at home, or do I need a professional device?

Home devices exist and are used in research, but quality varies widely. Consumer devices are not regulated the way medical devices are, so actual wavelength and power output may differ from claims. If you use a home device, look for specifications (wavelength in nanometers, power in milliwatts per square centimeter) rather than vague marketing language.

Is infrared therapy safe to use every day?

Daily use has not caused serious harm in published trials, but long-term safety data are limited. Occasional skin redness or warmth is the main reported effect. If you have photosensitivity, take photosensitizing medications, or have impaired skin sensation, check with a doctor first.

Will the benefits last after I stop treatment?

This is not well studied. Most trials end when treatment ends, so it is unclear whether improvements persist, fade gradually, or disappear. For acute soreness, benefits may fade within days or weeks. For chronic conditions, the pattern is unknown.