Red Light Therapy for Sprains: Scientific Evidence

A 2018 randomized controlled trial tested LED therapy against a placebo device during the first days of ankle sprain treatment. 47 participants received red light centered on 627 nm, within a 617 to 637 nm range, at 60 mW and 50 mW/cm,² delivering 100 J and 10 J/cm² to the injured ankle, given 6 times per week over 6 days alongside standard first-aid care. 75% of the light group improved by more than 40% by day 3, while none of the placebo group reached that level. The trial found larger reductions in swelling in the light group than in the placebo group at both day 3 and day 6, and greater pain relief by day 6.

Comparing ice treatment alone against ice treatment plus polarized polychromatic light, a 2017 randomized controlled trial examined moderate ankle sprains. 50 regularly active adults aged 18 to 35 were split into 2 groups of 25, with the light group receiving daily 10-minute sessions for 5 days at 40 mW/cm² and 24 J/cm², using light spanning 480 to 3400 nm applied over the injured area. The group that received light alongside ice treatment improved more than the ice-only group in pain, swelling, and how far the ankle could move by day 5, and the differences between the groups were statistically significant on every measure. According to the trial, this is preliminary evidence and larger studies are needed to confirm it.

47 soccer players in Greece with moderate ankle sprains took part in a 2004 randomized controlled trial comparing 3 treatment protocols, 1 of which added low-level laser therapy (LLLT). Players were split evenly, with 16 receiving standard first-aid care of rest, ice, compression, and elevation, 16 receiving that care plus a dummy laser, and 15 receiving that care plus LLLT, using a gallium aluminum arsenide laser emitting near-infrared light at 820 nm, 40 mW, and 16 Hz, giving 1.2 J and 7.5 J/cm² in 30-second sessions across 3 days. Swelling fell by 40.3 mL at 24 hours, 56.4 mL at 48 hours, and 65.1 mL at 72 hours in the group given the laser, and each reduction was statistically significant. Adding the laser to standard first-aid care appeared to reduce swelling more than that care alone or that care with a dummy laser.