Red light therapy is a possible add-on treatment for knee pain, especially pain linked to knee osteoarthritis, but it is not a proven cure and should not replace exercise, weight management, physical therapy, or medical treatment.
The evidence base includes a 2024 review of 10 randomized placebo-controlled studies involving 542 people, a 2025 clinical trial, and a 2025 umbrella review. Together, these studies suggest that red light therapy may reduce pain for some people, but the size and duration of the benefit remain uncertain.
Red Light Therapy for Knee Pain at a Glance
| Question | Evidence-based answer |
|---|---|
| Does red light therapy help knee osteoarthritis pain? | It may reduce pain compared with placebo in some studies. |
| Does it work for every type of knee pain? | No. Most research involves knee osteoarthritis, not every knee injury or condition. |
| Does it repair cartilage? | Human clinical research has not established that it repairs or regrows cartilage. |
| Is it a first-line treatment? | No. Exercise, strengthening, weight management when appropriate, and established pain treatments have stronger guideline support. |
| Is it generally safe? | It appears low risk when used correctly, but some people should avoid it or seek medical advice first. |
What Does the Research Say?
Research suggests that photobiomodulation may lower knee pain, but it has not established a dependable treatment effect.
A 2024 systematic review and meta-analysis examined 10 randomized placebo-controlled studies involving 542 people with knee osteoarthritis. Photobiomodulation reduced pain at rest compared with placebo. The researchers rated the certainty of evidence as very low because the studies were small, used different treatment settings, and had unclear or high risk of bias. The treatment did not significantly improve performance on the Timed Up and Go test.
A 2025 randomized controlled trial included 65 participants in its final analysis. The study used a 790-nanometer laser that delivered 4 joules per treatment point. It reported better pain and function outcomes than sham treatment and no treatment. One small trial cannot show that the same results will occur with consumer LED panels or other home devices.
A 2025 umbrella review found moderate-certainty evidence that photobiomodulation may improve disability related to knee osteoarthritis. It also found that most outcomes had low or moderate certainty because treatment protocols varied and high-quality research was limited.
What Does That Mean in Practice?
Some people with knee osteoarthritis may have less pain after a course of treatment, but the improvement may be modest and may not last. The research does not show that red light therapy rebuilds cartilage, removes arthritis, or allows someone to avoid standard treatment.
Most studies involve photobiomodulation, also called low-level light therapy or low-level laser therapy. It uses low-intensity visible red or near-infrared light. Researchers have proposed that it changes cellular activity and pain signaling without substantially heating the tissue.
Results can depend on the wavelength, dose, treatment time, distance from the device, and delivery method. A laser protocol used in a clinical trial may not produce the same result as a consumer LED panel.
Does Red Light Therapy Work for Knee Pain Other Than Osteoarthritis?
The evidence is much less certain for knee pain caused by meniscus tears, ligament injuries, tendinitis, bursitis, patellofemoral pain, gout, inflammatory arthritis, infection, or recent surgery.
Most clinical studies involve knee osteoarthritis, so their findings should not automatically be applied to every cause of knee pain. Persistent or unexplained pain should be assessed before you rely on a light device. The National Center for Complementary and Integrative Health advises against using complementary treatments as a substitute for proven medical care or as a reason to delay evaluation.
Is Red Light Therapy Worth Trying for Knee Osteoarthritis?
Red light therapy may be reasonable as an add-on treatment if:
- Your knee pain has been assessed.
- Osteoarthritis is the likely cause.
- You understand that any improvement may be modest.
- The device has clear safety and treatment instructions.
- You continue exercise and strengthening.
- You are not using it to delay necessary medical care.
It is a poor fit if you expect it to repair cartilage, permanently remove pain, or replace physical therapy and exercise.
What Treatments Should Come First?
For knee osteoarthritis, guidelines give stronger support to exercise, strengthening, self-management, weight loss when appropriate, and established pain treatments.
Common options include:
- Supervised, home-based, or aquatic exercise
- Quadriceps and lower-limb strengthening
- Self-management and patient education
- Weight loss when overweight or obese
- Topical nonsteroidal anti-inflammatory drugs when appropriate
- Oral pain medicines when medically suitable
- Braces or canes for selected patients
The American Academy of Orthopaedic Surgeons strongly recommends exercise over no exercise. It also recommends sustained weight loss to improve pain and function in people with knee osteoarthritis who are overweight or obese.
Red light therapy can be used alongside these treatments, but it should not displace them.
How Can You Use Red Light Therapy Safely?
Follow the schedule supplied by the device manufacturer or recommended by a qualified clinician. A device with higher advertised power is not automatically more effective. Results depend on the delivered dose, wavelength, distance, exposure time, and treatment area.
Use eye protection when the instructions require it. Do not look directly into bright LEDs or lasers.
The U.S. Food and Drug Administration warns that light-based devices can injure the eyes. It also lists situations in which photobiomodulation may not be appropriate, including:
- Photosensitivity disorders
- Pregnancy or planned pregnancy
- Active implanted devices such as pacemakers or defibrillators
- Cancer at the treatment site
- Photosensitizing medication
- Active infection, wounds, or lesions
FDA-cleared describes a device's regulatory status. It does not prove that the device will effectively treat knee pain. Effectiveness depends on whether the device delivers a treatment protocol that has been studied for the condition being treated.
Bottom Line
If you try red light therapy, treat it as a time-limited add-on rather than a replacement for diagnosis or treatment. Track changes in walking, stair use, sleep, and daily pain over several weeks. Stop if it causes skin irritation, worsening pain, or other symptoms.