Red Light Therapy for Pain: 10 Studies Show How It Works

Painkillers have devastating side effects. NSAIDs (even low-dose aspirin) can cause fatal peptic ulcers. Opioids such as fentanyl cause horrible addictions and unnecessary deaths. How can red light therapy help?

Takeaways:

Red light therapy for pain relief significantly reduces acute and chronic pain. In this article, you’ll learn about ten studies that show red light therapy reduced pain, including:

1. Carpal tunnel, wrist, and hand pain
2. Meniscus tear pain
3. Knee osteoarthritis pain
4. Delayed onset muscle soreness (DOMS)
5. Nerve injury and surgery pain
6. Bell’s Palsy muscle pain
7. Diabetic peripheral neuropathy pain
8. Mouth injection pain
9. Chemotherapy and radiotherapy oral injury side effect pain
10. Low back pain

Red Light Therapy for Pain

Red light therapy reduces pain via multiple biological mechanisms, including increased endorphin production, reduced cytokines signaling new inflammation, and suppression of pain signals through the nervous system.

When researching the science of red light therapy’s effects on pain, you will need to use the right vocabulary. Search for “photobiomodulation” and “low-level light therapy” rather than “red light therapy” to find thousands of studies. Here is a link to the National Institute of Health’s medical database to get you started: (“photobiomodulation” OR “low level light therapy” OR “low level laser therapy” OR “cold laser”) AND pain

These studies show that red light therapy for pain eases discomfort from surgery, delayed onset muscle soreness (DOMS), and dental injections. I pulled several of these studies to share with you in this article. These studies demonstrate how red light therapy reduces:

1. Carpal tunnel, wrist and hand pain
2. Meniscus tear pain
3. Knee osteoarthritis pain
4. Delayed onset muscle soreness (DOMS)
5. Nerve injury and surgery pain
6. Bell’s Palsy muscle pain
7. Diabetic peripheral neuropathy pain
8. Mouth injection pain
9. Chemotherapy and radiotherapy oral injury side effect pain
10. Low back pain

This list is hardly complete. There are also studies showing red light therapy reduces the pain of rheumatoid and osteoarthritis joint pain, migraine, and many more sources of discomfort, both chronic and acute.

In fact, when used for chronic pain, the issue might flare temporarily, because it is re-entering the acute phase. Within 24 hours, the acute pain returns to baseline and then falls as much as 100%.

#1 Red Light Therapy Reduces Carpal Tunnel Pain

Carpal tunnel is a repetitive stress injury causing pain, weakness, and swelling[1]. In a 2007 study of rheumatoid arthritis patients who also experienced carpal tunnel, researchers tested 780 nm infrared light to ease pain and restore functionality[2].

Ten subjects received red light therapy for ten days. The placebo group of nine subjects received a sham light treatment. Immediately after the study and three months later, subjects filled out standardized pain questionnaires. Researchers performed functional tests as well. The treatment group had significantly less pain after treatment and even three months later.

The group treated with red light therapy had a corresponding higher functional score as well. They were better able to use their wrists and hands than the placebo group. The authors concluded that red light therapy “may be used as a good alternative treatment method in CTS [carpal tunnel syndrome] patients with RA [rheumatoid arthritis].”

This study showed that red light therapy reduces carpal tunnel pain. That these subjects also had rheumatoid arthritis shows that the disease did not slow the therapeutic effect of red light therapy.

#2 Red Light Therapy Reduces Meniscus Tear Pain

The menisci are cartilage pads that protect the knees from shock. Tearing a meniscus is a common knee problem usually treated with arthroscopic surgery.[3]

A 2013 study tested the effects of red light therapy on meniscus tear pain. The subjects in this study had not yet received any other therapies[3a]. Thirty-two subjects received 904 nm infrared therapy, and another 32 subjects received sham light therapy. There were six treatments over a span of nine weeks.

Twenty-eight of the 32 patients in the treatment group had statistically significant pain reduction at four weeks and 52 weeks after the last treatment. This study showed that red light therapy could reduce torn meniscus pain as much as a year after treatment.

#3 Red Light Therapy Reduces Osteoarthritis Pain

Osteoarthritis of the knee is the loss of cartilage cushioning around the knee joint[4]. Knee osteoarthritis is a painful and supposedly irreversible condition.

In a 2019 study of red light therapy’s effect on osteoarthritis of the knee, researchers treated subjects’ quadriceps with very high amounts of low-energy 808 nm infrared light[5]. The subjects filled out standardized pain rating questionnaires and performed various exercises before and after the one red light therapy treatment.

The treatment group achieved a 54% reduction in perceived pain. They also gained speed when walking, and rising from a sitting position. They scored significantly higher on strength measurement tests as well. This study showed that high-dose low-energy infrared on the quadriceps reduces osteoarthritis pain. The therapy also restores strength and functionality.

#4 Red Light Therapy Reduces Delayed Onset Muscle Soreness (DOMS)

Delayed onset muscle soreness (DOMS) is the muscle fiber damage from new exercise movements[6]. DOMS is actually a sign of strengthening, as the body creates more muscle in response to the damage. However, the fact is, DOMS hurts. Ice (also known as cryotherapy) is a common home remedy for DOMS.

Researchers wanted to know if red light therapy would work as well as ice at reducing the soreness that sets in between 24 and 48 hours after exercise. According to a 2022 meta-analysis of exercise red light therapy studies, red light therapy is more effective than ice at reducing DOMS[7]. They analyzed the randomized clinical trials comparing red light therapy to cryotherapy for post-exercise soreness and strength.

They found statistically strong evidence that red light therapy improves muscle strength, reduces DOMS, and reduces the biomarkers that indicate exercise-induced muscle damage.

Red light therapy was more effective than ice therapy at reducing pain. This study showed that post-exercise red light therapy is an effective treatment to reduce the severity of delayed onset muscle soreness.

#5 Red Light Therapy Reduces Nerve Surgery Pain

It was not that long ago that nerve injuries were permanent. With an advancement called “neurotization,” surgeons can transplant healthy nerves into damaged ones, allowing the injury to heal and recover.

In a 2020 study, researchers tested whether red light therapy would ease the pain of neurotization surgery[8]. They performed the surgery on 14 subjects who could no longer bend their elbows due to nerve damage. Seven patients received post-surgery red light therapy, and seven received a sham treatment. Three months after the surgery, patients in the red light therapy group had more healthy nerve in their elbows, and reported less pain during the recovery.

This study showed that red light therapy could reduce the pain associated with nerve injury and surgery.

#6 Red Light Therapy Relieves Bell’s Palsy Pain (and Reverses Paralysis)

Bell’s Palsy is a paralysis of a facial nerve. Despite the patient’s inability to move some muscles, the disease causes intense pain in the facial muscles. Paralysis mainly affects children.

A 13-year-old girl had a painful case of Bell’s Palsy. She had no movement on the right side of her face, and could not close her right eye. She had intense pain when talking or chewing. Researchers gave the girl three red light therapy sessions totaling a relatively large dose of light.

The therapy eliminated Bell’s Palsy muscular pain when speaking or chewing. She had no muscular pain after just three sessions. The treatment also resulted in a complete resolution to the paralysis. This study showed that red light therapy could relieve the intense pain of Bell’s Palsy.

#7 Red Light Therapy Relieves Diabetic Peripheral Neuropathy Pain

A diabetic’s feet lose blood supply as the disease closes off circulation[9]. This causes nerve damage known as “diabetic peripheral neuropathy.” The “peripheral” refers to the limbs farthest from the heart, which loses nutrition and oxygen. The neuropathy causes terrible tingling and burning pain, especially in the feet, and often in the legs as well.

Researchers tested whether red light therapy could help with this grim pain. They studied the therapy on 50 patients with Type II diabetes and diabetic peripheral neuropathy. First, they tested the baseline levels of the subjects’ “neuron-specific enolase (NSE). NSE is an enzyme that rises in proportion to neural damage. Then they had the patients score their pain on a standardized pain rating scale. The researchers treated the tops and bottoms of the patients’ feet with red light therapy for a total of 10 days. After two weeks of treatment, the patients took the pain scale tests again.

Forty-two of the 50 (84%) patients had a statistically significant drop in NSE and scored significantly lower on the pain rating scale. This study showed that red light therapy could significantly reduce the pain of diabetic neuropathy.

#8 Red Light Therapy Minimizes Mouth Injection Pain

Novocain numbs the gums from pain, but the shot of Novocain is itself painful. That is why dentists anesthetize the gum with a 20% Benzocaine gel. Researchers know that some pain can still punch through the Benzocaine application. One of the ways they know this is through a heart rate test. When patients are in pain, their heart rates speed up.

A simple way to test whether red light therapy helped relieve injection pain was to test how fast the heartbeat was during the procedure. In a triple-blind, randomized, and placebo-controlled study of 30 children, researchers combined Benzocaine with red light therapy before injections[10]. The authors hooked the children to heart monitors to measure their heart rate before, during, and after the injection. After the procedures, the children rated their pain on a standardized pain scale.

The red light therapy significantly decreased the children’s pain perception during the shot. Their heart rates rose less than the group receiving topical gel without red light therapy. This study showed that red light therapy combined with Benzocaine suppresses pain more than Benzocaine by itself.

#9 Red Light Therapy Reduces Oral Injury from Chemotherapy

Chemotherapy causes multiple unwanted effects on healthy tissue, including mucositis and radiodermatitis. Mucositis is oral inflammation in the form of open wounds and sores. Radiodermatitis is a painful skin rash. Oncologists prescribe analgesics such as aspirin to control the pain of these cancer therapy side effects.

In a placebo-controlled study of red light therapy on mucositis and radiodermatitis, 15 patients received red light therapy, while 10 patients received sham treatment[11]. All but one of the 15 patients receiving light therapy had a significant reduction in pain. During the treatment period, the group receiving real light therapy required fewer analgesic doses than the placebo group.

#10 Red Light Therapy Reduces Low Back Pain

So many issues cause low back pain, from pulled muscles to degenerating discs. When the low back is out of order, so is getting anything done. Regardless of the cause, back pain often involves inflammation, something that red light therapy is good at resolving.

Researchers treated 45 subjects with chronic, non-specific low back pain, and separated them into three groups with 15 people each[11a]. The study was randomized, double-blinded, and placebo-controlled. The first group acted as a control. Group 2 received 650 nm red light therapy, and Group 3 received 830 nm infrared light therapy. The subjects took visual analog scale tests to score their pain levels at four and eight weeks into the study. The control group had no improvement during or at the end of the study.

The infrared group had functional improvements — they were better able to use their bodies for work. The infrared group had significant pain relief as well as functional improvement. Based on this study, one might believe that red light is better at reducing pain than infrared light. The fact is that there are more successful infrared pain relief studies. This is just one study. Science shows that red and infrared both have pain-relieving effects.

How Red Light Therapy Blocks Pain

Red light therapy relieves pain via multiple biological mechanisms. Red light therapy:

• blocks pain receptors
• reverses pro-inflammatory cytokines
• increases natural pain-killing hormones

Red light therapy blocks several neural channels that transmit pain to the brain, and it accelerates healing. Both reduce the amount of time and intensity of pain.

Red/Infrared Blocks Pain Receptors

“Bradykinin” is a peptide that causes multiple inflammation activities. When bradykinin arrives, inflammation begins. The injured area sends “nociceptive” signals that spell out “painful thing happening here” Those signals travel on “primary afferent neurons,” which is the telephone wire taking the message to the brain. The brain interprets the signal as pain.

In a study on pain signals, researchers introduced bradykinin to the cells[14]. After the inflammation cascade began, the researchers then introduced infrared light to the neurons. The light blocked the nociceptive signals, reversing the inflammation and sensation of pain. This study showed that red light therapy blocks the signals that sense pain, and short circuit the message to the brain to feel pain.

Red Light Alters Pro-Inflammatory Cytokines to Reduce Pain

“Transcription factors” are messages that tell genes to express themselves. Cytokines are transcription factors involved in inflammation. Red light therapy affects the behavior of at least three cytokines: hypoxia-inducible factor 1-alpha (HIF-1a), tumor necrosis factor-alpha (TNF-a), and interleukin-1b (IL-1b). HIF-a signals the sending of oxygen to oxygen-depleted muscles[15]^,[16]. TNF-a and IL-1b signal multiple inflammatory processes. These cytokines signal the body to create acute inflammation around an injury.

Researchers studied the effect of red light therapy on these injury responses. They created a chronic, constrictive injury in mice, and then tested cytokine levels. Half the mice received placebo treatments. Based on paw withdrawal threshold, and sciatic, tibial and peroneal functional indices, they found that the red light therapy significantly reduced the inflammatory injury response.

The therapy significantly reduced the HIF-1a, TNF-a, and IL-1b in test subject injury areas. This means that red light therapy reduces chronic inflammation, a common source of chronic pain.

Reducing Pain Killers

Red light therapy reduces the need for aspirin, NSAIDs, and opioids. As painkillers can cause internal bleeding, and opioids are addictive, reducing the need for these drugs reduces the deadly side effects of drugs[12]. More light therapy with no side effects and fewer drugs leads to fewer families ruined and fewer drug-related deaths.

Red Light Therapy Reduces FENTANYL Use After Surgery

Researchers tested whether red light therapy could reduce dependence on addictive painkillers, as well as analgesics such as aspirin and Ibuprofen. They tested red light against fentanyl and aspirin in a double-blind, placebo-controlled study of 48 patients with broken wrists.

In preparation for the bone-setting surgery, 48 patients received a lidocaine intravenous drip. The control group of 24 patients received a sham red light therapy session. The treatment group received actual red light therapy. After the surgery, patients took a standardized test to rate their perception of pain.

The group receiving red light therapy had significantly less pain than the lidocaine-only patients did.

During recovery, the treatment group received more light therapy, and the control group received more sham treatments. The group getting light therapy used less fentanyl and aspirin than the control group. This study showed that red light therapy reduced the dependence on addictive drugs and drugs with side effects.

Red Light Therapy Increases Pain Killer Hormones

The fascia is a stiff bag of connective tissue that holds the bones and organs in place[17]. Fascia has nerves and tightens in response to stress. Myofascial trigger points are painful stress responses that we often interpret as “muscle pain.”

Researchers tested the effect of red light therapy on myofascial trigger points in the neck and back. Fifty-six subjects who were in chronic pain participated in the double-blind, placebo-controlled study. The treatment group received small doses of red and infrared light therapy during six sessions that spanned a 2-week period. The control group received sham light treatments.

During the treatment period, the researchers tested the subjects’ plasma for beta-endorphin and adrenocorticotropic hormone (ACTH). These hormones defend against pain. As the sessions accumulated, the amount of pain-killing hormone rose.

Red light therapy had a cumulative effect on the body’s supply of beta-endorphin and adrenocorticotropic hormone. This study showed that red light therapy triggers the release of natural pain-killing hormones. The effect is cumulative over time.

Red Light Therapy Reduces NSAID Use After Surgery

In another broken wrist study, researchers tested red light therapy on a group of 50 subjects[13]. The triple-blind, placebo-controlled study started when the wrist casts were removed. The subjects took a standardized pain perception test to score their pain levels. Researchers treated 25 subjects with red light therapy. They gave the control group of 25 subjects a sham treatment with the light off.

After the subjects returned home, they engaged in a home physical therapy program as well. The subjects took the pain measurement test again. The results showed that the subjects in the red light therapy group had a lower level of pain. The red light therapy group also took fewer NSAIDs during their recovery. This means that despite taking fewer drugs, the red light therapy group had less pain. This study showed that red light therapy could replace NSAIDs and aspirin, at least to some degree.

Conclusion

Red light therapy is a universal pain killer because it is a Cox-2 inhibitor, similar to how Ibuoprofen works. Studies show that red light therapy reduces dental, surgical and muscular pain, and more. Reducing torn meniscus and osteoarthritis pain are just two of the many types of pain that red light therapy can reduce. Red light therapy makes aspirin and opioids work better and is more effective than aspirin and NSAIDs in some cases. Multiple cellular mechanisms create pain reduction. These include producing more endorphins, blocking pain signals, and speeding recovery.

References

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