Red Light Therapy for Rotator Cuff Injury: Scientific Evidence

A single-arm design gave all 20 participants the same treatment in a 2025 clinical trial of photobiomodulation (PBM) combined with exercise rehabilitation for rotator cuff injury. The group, 15 men and 5 women averaging 47.3 years of age and recruited in India, received 660 nm red light from a 19-diode cluster probe at 10 mW and 50 mW/cm², applied for 4 minutes at 156 Hz to the front and outer side of the affected shoulder for 10 days, followed by 4 weeks of structured exercise. Only 3 of the 5 shoulder movements measured improved significantly, with lifting the arm out to the side rising from an average of 120° to 170°, while raising the arm forward and taking it backward changed little. The trial found pain ratings on a 0-to-10 scale falling from an average of 7.33 to 2.50 across the 6 weeks. Every participant received both the light and the exercise, and no comparison group was included, so the effect of light on its own cannot be separated from the effect of exercise.

Comparing high-intensity laser therapy (HILT) against ultrasound therapy, a 2025 randomized controlled trial examined partial tears in a shoulder tendon that helps lift the arm. 50 adults aged 18 to 75 in Türkiye were randomly assigned to a 3-week course of either treatment, given 3 times per week by the same physiotherapist, with the laser group receiving 1064 nm near-infrared light at 12 and 100 J/cm², 300 and 2500 J, powers of 7, 8 and 12 W and a pulse rate of 25 Hz in sessions of 2.5 and 25.95 minutes, and 41 patients remained for analysis, 20 in the laser group and 21 in the ultrasound group. Pain ratings on a 0-to-10 scale dropped from a median of 7 before treatment to 1.5 by 12 weeks in the laser group, against a fall from 7 to 3 in the ultrasound group. Scores for shoulder pain and difficulty with everyday tasks followed the same pattern, and the laser group appeared to keep improving between weeks 4 and 12 while the ultrasound group leveled off. The thickness of the injured tendon did not change in either group at any point.

50 adults recovering from keyhole surgery to repair the rotator cuff took part in a 2023 randomized controlled trial in Israel that was double-blind and sham-controlled. Participants averaged 55 years of age, with 29 men and 21 women, and 22 were given an active photobiomodulation (PBM) device while 28 received an identical sham device, both self-applied at home alongside standard care and delivering 808 nm near-infrared light for 15 minutes at 16.5 J/cm² per session. 76% of the active PBM group reached a meaningful improvement in pain by 3 months compared with 48% of the sham group, and by 6 months 48% against 23% had reached a symptom level they found acceptable. Shoulder function scores and how far the shoulder could move improved to a similar degree in both groups, while difficulty using the arm and shoulder and both physical and mental quality-of-life scores improved faster with active PBM. The study concluded that self-applied light therapy after this surgery speeds the fall in pain and disability.