Infrared therapy shows some promise for arthritis pain relief, but the evidence is mixed and weaker than many product manufacturers suggest. Some studies report short-term reductions in pain and stiffness, particularly during and immediately after treatment sessions. However, well-designed placebo-controlled trials have found no significant difference between infrared treatment and sham devices for knee osteoarthritis outcomes, and major rheumatology organizations have not included infrared therapy in their official treatment guidelines.
What Infrared Therapy Does to Joint Tissue
Infrared light is a type of electromagnetic energy just beyond what your eyes can see. When applied to the body, it produces heat in the tissues it reaches. The therapeutic idea is that this energy stimulates cells to produce more of the fuel they need to repair and reduce inflammation, a concept called photobiomodulation.
The catch is penetration depth. Research using 820 nm infrared light (a common therapeutic wavelength) found that about 78% of the energy passes through the outermost 0.4 mm of skin, but only 10% makes it through 2 mm of skin. At 3 mm, essentially none was detected. A higher-powered 808 nm laser reached about 6 mm, but low-power LED devices couldn’t penetrate beyond 2 mm of human skin. Since the knee joint sits well below the skin surface, surrounded by muscle, fat, and connective tissue, it’s genuinely unclear how much infrared energy from consumer devices actually reaches the joint itself.
The World Association for Photobiomodulation Therapy recommends wavelengths of 780 to 860 nm and around 904 nm for musculoskeletal conditions. The 904-905 nm range penetrates somewhat deeper and may be more relevant for people with thicker tissue around the joint. But even researchers who support the therapy acknowledge that wavelengths in the 785-850 nm range have difficulty penetrating all the way into the knee joint.
Evidence for Knee Osteoarthritis
A double-blind, randomized, placebo-controlled study published in the Journal of Orthopaedic & Sports Physical Therapy tested monochromatic infrared energy therapy on patients with knee osteoarthritis. The results were clear: patients receiving real infrared treatment did not experience significantly different levels of pain relief, daily function, sports and recreation ability, psychological distress, fatigue, disability, or quality of life compared to patients receiving a placebo device. None of the outcome measures showed a statistically significant difference between the two groups.
This matters because it’s exactly the kind of study designed to separate real therapeutic effects from the placebo effect. When people hold a warm, glowing device against a sore knee, they often feel better regardless of whether the device is actually delivering therapeutic infrared energy. Placebo-controlled trials strip away that expectation, and in this case, the infrared therapy didn’t outperform the sham.
A network meta-analysis looking at the optimal wavelength for low-level light therapy in knee osteoarthritis did find that certain wavelengths (785-850 nm and 904-905 nm) showed some benefit for symptoms. The 904-905 nm wavelength, with its deeper penetration, appeared potentially useful for patients with severe cartilage damage or obesity-related osteoarthritis. But the researchers noted that questions about the right dose, power, treatment duration, and application site remain unresolved.
Evidence for Rheumatoid Arthritis
A pilot study tested infrared sauna sessions in patients with rheumatoid arthritis and ankylosing spondylitis (an inflammatory arthritis of the spine). Pain and stiffness decreased during infrared sauna sessions, with statistically significant improvements in RA patients (p < 0.05) and even stronger results in ankylosing spondylitis patients (p < 0.001). The key limitation: these improvements occurred during and immediately after sessions. Over the full four-week treatment period, the reductions in pain, stiffness, and fatigue did not reach statistical significance.
In practical terms, this means an infrared sauna session might make you feel temporarily better, similar to how a hot bath eases stiff joints. Whether that temporary relief translates into meaningful, lasting improvement in disease activity is a different question, and the data so far suggests it does not.
Why the Hype Outpaces the Science
Infrared therapy occupies an unusual space. There’s a plausible biological mechanism (light energy stimulating cellular repair), and some studies do show benefits. But the overall picture is inconsistent. A comprehensive review of photobiomodulation for arthritis noted “positive results” across various studies, yet also emphasized that fundamental questions about treatment parameters remain unanswered. Different studies use different wavelengths, power levels, treatment times, and application methods, making it difficult to compare results or write reliable treatment protocols.
Neither the American College of Rheumatology nor EULAR (the European League Against Rheumatism) includes infrared therapy in their official management guidelines for rheumatoid arthritis or osteoarthritis. This doesn’t mean it’s harmful or useless, but it does mean the evidence hasn’t reached the threshold where expert panels consider it a recommended treatment.
Safety Considerations
Infrared therapy is generally low-risk for most people. The main concerns are thermal burns, skin irritation, and eye damage from direct exposure. These risks are more relevant with high-powered clinical devices than with consumer products, but they’re worth knowing about.
Infrared therapy is contraindicated (meaning you should avoid it) if you have impaired sensation in the treatment area, since you may not feel a burn developing. This is particularly relevant for people with diabetic neuropathy, which commonly overlaps with arthritis. Other contraindications include poor circulation in the skin over the treatment area, active skin conditions like dermatitis or eczema, active infections, and fever. If you use a far infrared sauna rather than a targeted device, dehydration and low blood pressure are additional concerns.
What This Means in Practice
If you’re considering infrared therapy for arthritis, the honest picture is this: it might provide temporary pain relief similar to other heat-based treatments, but there’s no strong evidence it changes the course of arthritis or provides lasting benefits beyond what a heating pad or warm bath could offer. The most rigorous placebo-controlled research for knee osteoarthritis found no advantage over a sham device.
Some people do report feeling better after infrared sessions, and that subjective relief is real even if the mechanism isn’t fully proven. If it fits your budget and you find it comfortable, it’s unlikely to cause harm for most people. But it should complement established treatments (exercise, weight management, physical therapy, and medications when needed), not replace them. The lack of standardized treatment protocols means that even if infrared therapy works at certain wavelengths and power levels, no one can yet tell you exactly which device to buy or how long to use it for optimal results.