Red Light Therapy for Osteoarthritis: What the Evidence Actually Shows

By the RedLightPainLab Research Team · Published June 8, 2026 · Last updated June 8, 2026

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Red light therapy, also called photobiomodulation or low-level laser therapy (LLLT), is the use of red and near-infrared light on the body. For osteoarthritis it can take the edge off the pain, and the knee is where it has earned the most credibility. Pooled trial data show red and near-infrared light easing knee OA pain, usually working best as a partner to exercise rather than a fix on its own. The story for hands is thinner. If you want to try it, aim a near-infrared device at the sore joint for 10 to 15 minutes most days and give it a few weeks before you judge it.

Does red light therapy work for osteoarthritis?

For the knee, the answer is a qualified yes. In 2019, a team writing in BMJ Open pooled 22 randomized, placebo-controlled trials covering 1,063 people and found low-level laser and light therapy beat a sham treatment for knee OA pain. The gap was about 14 mm on a 100 mm pain scale right after treatment, and it actually widened to roughly 32 mm two to four weeks later once you look only at the better-studied doses. Disability scores improved too, and no one reported harm from the light itself (Stausholm et al., BMJ Open, 2019).

A 2024 review in Physical Therapy went back over the question across 10 studies and 542 patients, and it landed in a similar spot: pain at rest dropped against placebo, a standardized mean difference of -0.7, which counts as a moderate effect. The authors were blunt about the catch, though. They rated the certainty of that result as very low and said photobiomodulation belongs next to proven treatments like exercise, not in their place (Physical Therapy, 2024). Plenty of articles quietly leave out that second half.

How does it actually work on a sore joint?

The short version is that it gives your cells more fuel. Red and near-infrared light gets absorbed by an enzyme in your mitochondria called cytochrome c oxidase. When that happens, the enzyme releases the nitric oxide that had been throttling energy production, the cell’s power chain speeds back up, and ATP output climbs (Hamblin, Photochemistry and Photobiology, 2018). In a cranky joint, a bit more energy and a bit less local inflammation can add up to less pain. What it cannot do is rebuild cartilage or undo the wear that defines osteoarthritis, so anyone promising that is overselling.

What does the evidence show for each joint?

Osteoarthritis behaves differently depending on where it sits. The light has to physically reach the joint, and both joint depth and the quality of the research vary a lot, so the answer shifts as you move from the knee to the hand.

Sources: Stausholm 2019, Physical Therapy 2024, Brosseau 2005.

The knee

This is the strongest case by a distance. Both meta-analyses point the same way, and the 2019 paper even teased out a dose-response. The wins clustered at 4 to 8 joules at 785 to 860 nm, or 1 to 3 joules at 904 nm, per spot. The practical reading: hitting the right wavelength at a real dose matters more than parking under the panel forever, and the studies that moved the needle paired the light with an exercise program.

The hands and thumbs

Temper your hopes here. When researchers put 88 people through six weeks of laser therapy against a sham, the active group did no better on pain, morning stiffness, or function, though a couple of side measures like grip strength nudged ahead (Brosseau et al., 2005). The newer hand studies have not settled it either. If your osteoarthritis lives in your fingers or thumb, go in with modest expectations.

What about the hip, shoulder, or spine?

Here the honest answer is that the direct trial evidence thins out fast. Almost all of the strong osteoarthritis research sits on the knee, with a little on the hands. Larger, deeper joints like the hip are also physically harder for light to reach, because the joint can sit several centimeters below the surface. Shoulders are easier to get at than hips, but the studies are sparse. If you treat one of these joints, treat it as an experiment: aim near-infrared at the joint from a close, comfortable distance, and anchor your expectations to the knee data rather than to marketing.

What wavelength is best, and why does depth matter?

For a joint, near-infrared is the part that earns its keep, because the joint sits too deep for red light to do much on its own. Inside the so-called optical window of roughly 600 to 1100 nm, the longer the wavelength, the deeper it travels. Red light around 660 nm mostly stops at the skin and the tissue just beneath it. Near-infrared from about 800 nm upward pushes further toward the joint. That one fact is why this site keeps circling back to depth.

Here is the thing we will not oversell. Most of the osteoarthritis trials that worked sat in the 785 to 905 nm range. The argument for 1064 nm reaching the deepest joints is good physics, but the high-quality 1064 nm trials in osteoarthritis specifically are still thin on the ground. So treat “deeper is better” as a well-grounded hunch, not a closed case. Our depth and wavelength science page digs into the trade-offs.

How to use red light therapy on an arthritic joint

The setups that worked in the studies were not fancy. They aimed the light straight at the joint, kept the sessions short, and repeated them. Here is a routine you can copy at home.

1. Pick a device with near-infrared (around 800 to 850 nm or longer), not a red-only panel.
2. Sit 6 to 24 inches from the joint, with bare skin facing the light.
3. Run 10 to 15 minutes per joint, about 5 days a week.
4. Work the joint from a few angles. For a knee, that means front, back, and the sides.
5. Keep up your exercise. The combination is what the trials rewarded.
6. Give it 4 to 6 weeks, and wear the eye protection.

Is it safe, and who should skip it?

Safety is the easy part. Across the osteoarthritis trials, side effects were rare to nonexistent. The few that turn up are mild: a little eye strain if you skip the goggles, some warmth, or short-lived redness if you crowd the panel. Wear the eye protection that ships with the device, stick to the suggested distance and time, and check with your doctor first if you are pregnant, take a medication that makes you sensitive to light, or have a condition that does.

How does it stack up against other treatments?

Treat red light as a sidekick, not the hero. Exercise, weight management, and physical therapy still carry the strongest osteoarthritis evidence, and that 2024 review put photobiomodulation squarely in the support role beside them. Its appeal is that it is drug-free and low risk, which makes it a sensible thing to stack on top of the basics, especially if you are trying to lean on pain pills less often. Run the plan past your clinician.

What does it cost, and will insurance cover it?

Expect to pay out of pocket. In the US, insurance rarely covers red light therapy for osteoarthritis, because it is treated as a general wellness tool rather than a proven medical treatment. In practice the choice is between paying a clinic for each visit, which adds up across a multi-week course, or buying a home panel once and using it as often as you like. Home units are usually less powerful than clinic machines, so they can take longer to show an effect; that is the trade-off for the lower running cost. Either way, the money only makes sense if you also keep up the exercise and the basics that carry the real evidence.

Choosing a device for osteoarthritis

For a joint, the spec that counts is real near-infrared output at enough power to reach the tissue from a comfortable distance, backed by third-party testing rather than a marketing sticker. That is the lens behind our top 5 devices for pain. Our current pick for depth and value is the RLT Home TotalSpectrum, which carries the near-infrared and deep near-infrared bands that suit joints.

Frequently asked questions

Does red light therapy work for knee arthritis?

The knee is its best result. Two separate meta-analyses found red and near-infrared light eased knee OA pain compared with a placebo, and disability improved as well. The effect is real but the certainty is low, so use it alongside exercise rather than on its own.

How long before it helps?

Give it a few weeks. In the knee trials the benefit built over a course of sessions and often peaked two to four weeks after the course ended. A fair trial looks like 10 to 15 minutes per joint, most days, for 4 to 6 weeks.

What wavelength should I look for?

Near-infrared, because the joint sits below the surface. The successful trials mostly used 785 to 905 nm. A 660 nm red-only panel is built for skin, so for arthritis you want near-infrared, and ideally deep near-infrared for bigger joints.

Can it reverse osteoarthritis or regrow cartilage?

No. The evidence is about easing pain and improving function, not about reversing the joint changes of osteoarthritis or growing back cartilage. Think of it as symptom relief that sits on top of exercise and medical care.

Is red light therapy FDA approved or cleared for arthritis?

Neither. Red light therapy panels are FDA registered, not FDA cleared or approved. Registration just means the maker has listed the device with the FDA as a general wellness product; it is paperwork, not proof that it treats arthritis. A handful of medical laser units carry the higher 510(k) clearance, but the consumer panels you will actually shop for do not.

Will it help arthritis in my hands?

Probably less than you would hope. A randomized trial found laser therapy did no better than a sham for hand OA pain, stiffness, or function. It can still be worth a careful try, but the case is much weaker than it is for the knee.

References

1. Stausholm MB, et al. Efficacy of low-level laser therapy on pain and disability in knee osteoarthritis: a systematic review and meta-analysis of randomised placebo-controlled trials. BMJ Open. 2019;9(10):e031142. PubMed
2. Effectiveness of photobiomodulation in reducing pain and disability in patients with knee osteoarthritis: a systematic review with meta-analysis. Physical Therapy. 2024;104(8):pzae073. Journal
3. Brosseau L, et al. Randomized controlled trial on low level laser therapy (LLLT) in the treatment of osteoarthritis (OA) of the hand. Lasers in Surgery and Medicine. 2005. PubMed
4. Hamblin MR. Mechanisms and mitochondrial redox signaling in photobiomodulation. Photochemistry and Photobiology. 2018;94(2):199-212. PMC

Medical disclaimer: This article is for informational purposes only and is not medical advice. Always consult a qualified healthcare professional before starting any new treatment, including red light therapy.

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