What infrared light does and doesn't do
Infrared light is electromagnetic radiation with wavelengths longer than visible red light—roughly 700 nanometers to 1 millimeter. When infrared light reaches your skin, it converts to heat and penetrates into tissue below the surface. This heat can increase blood flow, reduce inflammation markers in lab settings, and ease muscle soreness after exercise. The effect is real and measurable, but it is not a cure or treatment for disease.
The distinction matters because infrared light's actual effects are narrower than marketing claims suggest. Human studies show it can reduce pain and swelling in specific contexts—delayed-onset muscle soreness, minor joint inflammation, wound healing—but the evidence is strongest for short-term relief rather than long-term reversal of chronic conditions. Animal studies and lab work hint at deeper cellular effects, but those have not consistently translated to human benefit.
Infrared light comes in two main forms: near-infrared (700–1400 nm), which penetrates deepest and is used in most research devices, and far-infrared (3000–1000 nm), which produces more surface heat and is common in saunas and heating pads. The two behave differently in tissue, so studies of one do not automatically explore to the other.
Key Takeaways
- Infrared light increases blood flow and tissue temperature, which can reduce muscle soreness and minor inflammation in the short term, but human evidence for long-term disease reversal is limited.
- Near-infrared light penetrates deeper into tissue than far-infrared, so the two are used for different purposes and studied separately.
- Most human studies involve small groups and short follow-up periods, so larger and longer trials are needed to confirm effects beyond a few weeks.
- Infrared light is not a substitute for medical care; it may complement physical therapy or pain management but should not replace diagnosis or treatment of underlying conditions.
How infrared light affects tissue at the cellular level
The main mechanism involves mitochondria, the energy-producing structures inside cells. Near-infrared light is absorbed by cytochrome c oxidase, an enzyme in the mitochondrial electron transport chain. In lab and animal studies, this absorption increases ATP production—the cell's energy currency—and reduces oxidative stress. The theory is that more ATP allows cells to repair damage faster and reduces inflammation.
This mechanism is well-established in cell cultures and animal models. Mice exposed to near-infrared light show faster wound healing, reduced inflammatory markers, and improved muscle recovery after injury. However, the leap from mouse tissue to human tissue is not automatic. Human skin is thicker, blood flow patterns differ, and the dose of light that reaches deep tissue in a living person is much lower than in a laboratory dish.
Far-infrared light works differently. It does not penetrate as deeply and produces its effects mainly through heat—increasing local blood flow, relaxing muscle, and triggering the body's natural cooling response. This is why far-infrared saunas feel warm but do not require the specialized devices that near-infrared therapy uses.
What human studies show about muscle soreness and recovery
The strongest human evidence involves delayed-onset muscle soreness (DOMS)—the ache that appears 24 to 48 hours after intense or unfamiliar exercise. Several small randomized trials found that near-infrared light applied to the affected muscle reduced soreness and improved strength recovery over 3 to 7 days. A 2017 systematic review in Photomedicine and Laser Surgery identified 22 studies on DOMS and infrared light; most showed benefit, but study sizes ranged from 10 to 40 people, and follow-up lasted days to weeks, not months.
The effect size is modest—typically a 20 to 30 percent reduction in soreness compared to placebo or no treatment. This is meaningful for an athlete or someone returning to exercise, but it is not dramatic. The benefit appears to fade once treatment stops, so infrared light seems to speed recovery rather than produce lasting change.
For other types of pain—chronic joint pain, arthritis, fibromyalgia—the evidence is thinner. A few small trials suggest infrared light may reduce pain in osteoarthritis of the knee or shoulder, but the studies involved 20 to 50 people, lasted 4 to 12 weeks, and often lacked a true control group. Larger, longer trials are needed before infrared light can be called a standard approach to chronic pain.
Wound healing and skin health
Infrared light has been studied for its effect on wound healing, particularly in diabetic foot ulcers and surgical wounds. The theory is that increased blood flow and ATP production speed tissue repair. Animal studies consistently show faster healing with infrared exposure. In humans, the evidence is mixed and limited by small sample sizes.
A 2014 review in Photomedicine and Laser Surgery found that near-infrared light reduced healing time in some surgical wounds and chronic ulcers, but the studies involved 10 to 30 people and lasted weeks to months. Some trials showed no difference compared to standard care. The quality of evidence is rated as low to moderate, meaning larger and better-designed studies are needed.
For general skin health—collagen production, wrinkle reduction, skin tone—infrared light is marketed heavily but studied minimally in humans. Animal and cell studies suggest it may stimulate collagen synthesis, but human trials are rare and small. Any skin benefit would likely require repeated, long-term exposure, and the effect would be modest compared to sun protection or retinoid use.
Inflammation and immune response
Infrared light reduces inflammatory markers in blood and tissue in animal studies and cell cultures. Exposure lowers levels of tumor necrosis factor (TNF), interleukin-6 (IL-6), and other cytokines that drive inflammation. In theory, this could help with inflammatory conditions like rheumatoid arthritis or inflammatory bowel disease.
In humans, the evidence is preliminary. A small 2019 trial found that near-infrared light reduced inflammatory markers in people with knee osteoarthritis, but the study involved 40 people and lasted 12 weeks. Another study in people with chronic pain found reduced IL-6 after infrared treatment, but again, the sample was small and follow-up was short. These results are promising but not yet strong enough to recommend infrared light as a primary treatment for systemic inflammation.
It is also unclear whether reducing inflammatory markers in the short term translates to long-term health benefit. Inflammation is necessary for healing and immune defense; suppressing it too broadly or for too long can be harmful. No long-term studies have tracked whether infrared light exposure changes disease outcomes or reduces complications in inflammatory conditions.
Safety and practical considerations
Infrared light is generally safe for skin and eyes when used at standard therapeutic doses. Near-infrared light does not cause sunburn because it does not damage DNA the way ultraviolet light does. However, excessive heat can cause burns, so devices should have built-in temperature controls and should not be used on broken skin or areas with impaired sensation (such as diabetic neuropathy).
Infrared light devices vary widely in wavelength, power output, and design. A small handheld device used at home delivers far less light to deep tissue than a clinical panel used in a physical therapy office. This matters because most human studies used clinical-grade devices, so results from a study may not explore to a consumer product. The FDA does not regulate infrared light devices as strictly as it does drugs or medical devices, so quality and consistency vary.
Cost is also a practical factor. Clinical infrared light therapy sessions typically cost $25 to $75 per session, and benefit usually requires multiple sessions over weeks. Consumer devices range from $50 to several hundred dollars. For comparison, ice, compression, elevation, and over-the-counter pain relievers are cheaper and have stronger evidence for acute muscle soreness.
Infrared light versus other light therapies and heat treatments
Infrared light is often grouped with red light therapy and photobiomodulation, but they are not identical. Red light (600–700 nm) is visible and overlaps with near-infrared in some wavelengths. Both are studied for similar effects—wound healing, muscle recovery, pain reduction—and the mechanisms are related. However, red light penetrates less deeply than near-infrared, so the two are used for different tissues.
Infrared light also overlaps functionally with heat therapy—heating pads, hot baths, saunas. Both increase blood flow and reduce muscle tension. The advantage of infrared light is that it penetrates deeper than surface heat and may trigger cellular effects beyond warming. The disadvantage is that it requires a device, costs more, and the added benefit over straightforward heat is not always clear. For acute muscle soreness, a heating pad may be just as effective and cheaper.
Far-infrared saunas are marketed for detoxification and weight loss, but evidence for these claims is weak. Saunas do increase heart rate and blood flow, similar to moderate exercise, but they do not burn significant calories or remove toxins more effectively than the liver and kidneys do naturally. The relaxation and mild cardiovascular stimulus from sauna use may have health value, but that is separate from infrared light's specific cellular effects.
What remains unknown
The biggest gap in infrared light research is the lack of large, long-term human trials. Most studies involve 20 to 50 people, last weeks to a few months, and measure short-term outcomes like pain or soreness. No large trial has tracked whether infrared light changes the course of a chronic disease, reduces disability, or improves quality of life over years.
It is also unclear which wavelengths, doses, and treatment schedules work best for which conditions. Studies use different devices, different numbers of sessions, and different intervals between sessions. This makes it hard to compare results or know what dose a person should use at home. Standardization would help, but it has not happened yet.
Finally, the mechanisms observed in cells and animals may not fully explain what happens in whole humans. Infrared light may trigger effects in the lab that do not occur reliably in living tissue, or the body may compensate in ways that reduce the net benefit. Only larger human studies can answer these questions.
Frequently Asked Questions
Can infrared light replace physical therapy or pain medication?
No. Infrared light may reduce soreness or swelling alongside physical therapy or medication, but it should not replace them. If you have a diagnosed condition or chronic pain, work with a healthcare provider to develop a complete plan. Infrared light can be one tool in that plan, not the only one.
How long does it take to see results from infrared light?
For muscle soreness, studies show benefit within 3 to 7 days of treatment. For chronic pain or wound healing, results take weeks to months, if they occur at all. Many people see no change. Benefit usually fades once treatment stops, so ongoing use is needed to maintain any effect.
Is infrared light safe for all skin types?
Infrared light does not cause sunburn and is generally safe for all skin types. However, do not use it on broken skin, areas with impaired sensation, or over active infections. If you have a skin condition or take medications that increase light sensitivity, ask a healthcare provider before using infrared light.
What is the difference between near-infrared and far-infrared light?
Near-infrared penetrates deeper into tissue and is used in clinical devices for muscle and joint pain. Far-infrared produces more surface heat and is used in saunas and heating pads. The two have different effects and are studied separately, so results from one do not explore to the other.
Do consumer infrared light devices work as well as clinical ones?
Most human studies used clinical-grade devices with higher power output than consumer products. A handheld home device delivers much less light to deep tissue. Consumer devices may help with surface pain or soreness, but they are unlikely to produce the same results as clinical treatment. Check the device specifications and compare them to the studies you are reading.