Red light therapy for rheumatoid arthritis is something many people start reading about after months or years of managing the disease with medication. The morning stiffness that takes an hour to ease, the swollen knuckles, the pain that flares even when bloodwork improves: these are the parts of RA that send people looking for something to add to their treatment. Red and near-infrared light has been tested in people with rheumatoid arthritis since at least 1980 (Goldman et al., 1980). The early placebo-controlled trials were later pooled in a Cochrane review. Researchers call the therapy photobiomodulation, and the human trials used a form called low-level laser therapy. Lab teams have also shone light on joint cells taken from RA patients, and on arthritic animals, to see what happens to the inflammation inside a joint.
Key Takeaways
- A Cochrane review pooled placebo-controlled trials in rheumatoid arthritis. About four weeks of laser treatment, mostly on the hands, cut pain by 1.1 points on a 10-point scale and shortened morning stiffness by about 28 minutes. No side effects were reported (Brosseau et al., 2005). In a randomized trial presented at a 2021 rheumatology meeting, people added laser treatment to methotrexate. At six months, they had less pain, shorter morning stiffness, and less need for anti-inflammatory painkillers than people on methotrexate alone (Zhuravleva et al., 2021).
- In lab studies, red and near-infrared light lowered inflammation signals in joint-lining cells taken from people with rheumatoid arthritis. In arthritic mice, red LED light reduced joint inflammation and cartilage damage. Paired with methotrexate, it worked better than either treatment alone (Yamaura et al., 2009; Ryu et al., 2023).
What Rheumatoid Arthritis Does, and Where Standard Treatment Falls Short
Rheumatoid arthritis is an autoimmune disease, which sets it apart from the wear-and-tear joint disease covered in our review of red light therapy for osteoarthritis. In RA, the immune system attacks the thin lining inside the joints. That lining swells and thickens, and over the years the inflamed tissue can wear away cartilage and bone. The knuckles, wrists, and ankles are among the joints it hits most often (Lourinho et al., 2023).
Methotrexate and other disease-modifying drugs are the foundation of RA care. They take time to work, and they can significantly slow the disease (Zhang and Qu, 2023). They don't work fully for everyone, though. Between 30% and 40% of people do not respond well enough to methotrexate on its own (Goodman et al., 2015). Its most commonly reported side effects are stomach and digestive problems, which affect about one in three people who take it (Sherbini et al., 2021). Biologic drugs carry their own trade-off. At standard doses, they bring about six more serious infections per 1,000 people each year than traditional drugs (Singh et al., 2015).
For people whose medication helps but doesn't fully settle their joints, researchers have studied light therapy as something to add to that care.
Disease-modifying drugs are the foundation of rheumatoid arthritis care, and patients should stay on them. What makes the light therapy research worth a close look is where the light acts. In lab studies, it calmed inflamed joint-lining cells taken from people with RA, and in placebo-controlled trials, short courses eased pain and morning stiffness with no side effects reported. For patients who still have pain or stiffness on their medication, that makes light therapy a reasonable addition to discuss with their rheumatologist.— William Carter, MD
How Red Light Therapy Works for Rheumatoid Arthritis
Red and near-infrared light passes through the skin and is absorbed inside cells. Its main targets are an enzyme in the part of the cell that makes energy and certain channels that control calcium levels (Hamblin, 2017). In the same review, light therapy researcher Michael Hamblin listed lower inflammation as one of the therapy's most reliably repeated effects. He called that effect particularly important for joint disorders. Our review of red light therapy for inflammation looks at the same effect in other conditions.
Clinical Trials of Red Light Therapy for Rheumatoid Arthritis Pain and Stiffness
A Cochrane review pooled six studies of low-level laser therapy (LLLT) with more than 220 people with rheumatoid arthritis (Brosseau et al., 2005). Laser light went mostly on the hands, usually two to three times a week for about four weeks. Compared with placebo, pain dropped 1.1 points on a 10-point scale and morning stiffness was about 28 minutes shorter. Fingertips could also bend 1.3 cm closer to the palm. None of the studies reported side effects. The reviewers concluded that laser therapy could be considered for short-term relief of pain and morning stiffness, especially since it has few side effects. Research on the knee, including rheumatoid arthritis of the knee, is collected in our review of red light therapy for knee pain.
Two later meta-analyses added to the picture. A 2021 analysis of 10 controlled trials found significant pain relief right after a course of laser treatment, along with better physical function (Chia et al., 2021). A 2024 meta-analysis pooled 22 studies and found stronger grip and shorter morning stiffness, and its authors wrote that laser therapy shows promise for both (Salajegheh et al., 2024).
What happens when light is added to the drugs people already take? Two randomized trials tested exactly that. One 114-person trial was presented at the 2021 EULAR rheumatology meeting as a conference abstract, a short summary rather than a full published paper. In it, half the people added laser treatment of their joints to methotrexate (Zhuravleva et al., 2021). Those who did were more likely to cut back on anti-inflammatory painkillers: 21 of 57, compared with 10 of 57 on methotrexate alone. At the six-month check, the laser group also had less pain and shorter morning stiffness. An independent review put the stiffness difference at about 18 minutes and rated that evidence as low certainty (Lourinho et al., 2023). A smaller trial of 60 adults aged 65 to 75 added four weeks of laser treatment at acupuncture points to methotrexate and an exercise program. Compared with methotrexate and exercise alone, the laser group had lower levels of two blood markers of inflammation and better quality-of-life scores (Adly et al., 2022).
Red Light Therapy Dose: Why More Is Not Always Better
The rheumatoid arthritis trials in the Cochrane review used many different wavelengths and doses. Grouping the trials by those settings showed no significant differences. The reviewers wrote that they lacked the data to say how wavelength, dose, session length, or the treated spot changes the result. They called for trials designed to find out (Brosseau et al., 2005). A 2021 meta-analysis of 10 RA trials offered a first clue. High-intensity clinic lasers, and light aimed over nerves, gave more pain relief right after treatment. The analysis found no clear link between results and either wavelength or the number of sessions (Chia et al., 2021).
Across light therapy research, effects rise with dose up to a point, then fall off, and very high doses can work against the goal. Researchers call this pattern a biphasic dose response. Animal studies of arthritis show it plainly (Hamblin, 2017). In arthritic rats, a moderate laser dose reduced inflammation, inflammatory cells, and an enzyme that damages cartilage. A dose 16 times higher had no measurable effect (Hsieh et al., 2014). A rat study from the Wellman Center for Photomedicine found that how long the light was applied mattered more than the total dose. Sessions of 10 minutes or longer worked, and one-minute sessions did not (Castano et al., 2007).
How Red Light Therapy Affects Joint Inflammation in Rheumatoid Arthritis
At the Wellman Center for Photomedicine at Massachusetts General Hospital, a lab study tested near-infrared light on joint-lining cells taken from people with rheumatoid arthritis (Yamaura et al., 2009). The light lowered several of the inflammation signals that drive the disease, including the same signal that the most widely used biologic drugs are designed to block.
Red LED light went through a similar test in 2023, this time in both RA joint-lining cells and mice given a standard lab form of the disease (Ryu et al., 2023). In the cells, light cut how much the inflamed cells multiplied, moved, and invaded nearby tissue. Two weeks of daily treatment reduced joint inflammation and cartilage damage in the mice. The team also put light up against methotrexate. The combination beat either treatment alone, and the authors concluded that the two work together.
A separate red LED lab study found that light switched on a gene in RA joint-lining cells, and in two mouse models of arthritis, higher levels of that gene came with less joint damage (Du et al., 2023).
How Red Light Therapy Affects Immune Cells in Rheumatoid Arthritis
Some immune cells can switch between fueling inflammation and repairing tissue. They are called macrophages. Hamblin's review reported that light lowered inflammation markers in macrophages that were already active. In resting macrophages, light could have a stimulating effect instead (Hamblin, 2017). A 2023 lab study, using macrophages that did not come from RA patients, found the same split. In macrophages already driving inflammation, near-infrared light lowered inflammation markers and raised repair markers. In resting macrophages, it raised both (Tian et al., 2023).
In rats developing a lab form of rheumatoid arthritis, red light's effect on immune cells reached beyond the joint itself. Applied while the arthritis was developing, the light reduced the number of immune cells in the lymph nodes that drain the affected joints. Adding resistance exercise on top of the light did not increase that benefit (Reginato et al., 2026).
Red Light Therapy and Cartilage Protection in Rheumatoid Arthritis
Two rat studies looked directly at cartilage and joint tissue. In rats with a lab-induced form of rheumatoid arthritis, near-infrared laser three times a week lowered the enzymes that break down cartilage. The treated cartilage also withstood more force before breaking (Fernandes et al., 2025). Pain sensitivity improved after two weeks of treatment. One week was not enough.
A 2013 study in arthritic rats examined joint tissue under the microscope after laser treatment (Alves et al., 2013). Eight measures of inflammation and tissue repair improved compared with untreated arthritic rats. Timing made little difference: the gains held whether treatment started 12 hours after arthritis was triggered or a full week later.
How Red Light Therapy Acts on Pain
Rheumatoid arthritis trials measured pain relief. Broader pain research suggests how light might produce it. A 2021 narrative review of pain research across conditions concluded that light therapy appears to act on pain through several routes at once. These include the nerves that carry pain signals, the body's own pain-relieving system, and inflammation (Cheng et al., 2021). Most of the evidence behind it comes from animal studies. Two of the review's authors disclosed a patent and a business partnership related to green-light therapy.
Proteins the Immune System Targets in Rheumatoid Arthritis
A five-person lab study asked one of the most specific questions in rheumatoid arthritis light research. Could light lower the very proteins the immune system attacks? Researchers took joint-lining tissue removed during knee surgery from five people with rheumatoid arthritis. They treated it with near-infrared laser light (Bálint et al., 2011). In RA, the immune system attacks certain proteins once they have been chemically altered, and the laser reduced two of those proteins. One fell in four of the five samples, the other in two. The authors proposed that lowering the immune system's targets could be part of how laser therapy helps.
Conclusion
Red light therapy for rheumatoid arthritis has its firmest support where it has been tested most. Short courses of laser treatment on the hands eased pain and morning stiffness compared with placebo, with no side effects reported. Lab and animal research offers a believable explanation for why, with light calming inflamed joint cells, moving immune cells toward repair, and protecting cartilage in arthritic animals. Light therapy is a low-risk option, studied as an addition to the treatment that already protects your joints.
