Red Light Therapy for Raynaud's Disease: Scientific Evidence

Comparing 78 people with Raynaud's disease, 75 of them women, against 30 healthy volunteers, a 2015 clinical trial tested Multiwave Locked System laser therapy on attacks and on the tiny blood vessels at the base of the fingernail. 38 of the patients had the primary form of the condition and 40 the secondary form, at an average age of 42.8 years. A scanner passed near-infrared light over their fingertips and the backs of both hands, running 808 nm continuously and 905 nm in pulses at 3.3 W, 1500 Hz, 129.3 J, and 1.6 J/cm², for 2.5 minutes per hand, 5 days a week across 21 days. 73.7% of the primary-form patients had normal small vessels afterward, up from 55.3% before treatment, while severe damage in the secondary-form group fell from 57.5% to 42.5%. Attacks became fewer, shorter and less painful in both groups, and the researchers concluded that the laser appeared to help symptoms and small vessels alike.

Whether a patient's own symptom pattern could predict the success of laser therapy was examined in a 2004 randomized controlled trial of the primary form of Raynaud's disease. 48 patients received both low-level laser therapy (LLLT) and a sham version in a crossover design, with red light at 640 to 685 nm applied to the fingers and the backs of the hands at 200 mW and 2 J/cm², 5 days a week for 21 days in each phase. Attacks became both less frequent and less intense during the laser phase than during the sham phase, while heat-based imaging showed no significant change. The effect appeared strongest in patients whose blood vessels narrowed at a lower threshold and weakest in those whose blood flow was slow to return. Triggers other than cold, how long the fingers took to warm up, and the size of the temperature drop after cold exposure all helped predict who responded.

A 2004 randomized controlled trial evaluated low-level laser irradiation against a placebo in 47 people with the primary or secondary form of Raynaud's disease. 24 were assigned to laser treatment, 16 women and 8 men at a median age of 45, and 23 to a placebo version, 21 women and 2 men at a median age of 46. The laser sessions used red light at 670 nm delivered at 2.2 mW/cm² from a 400 mW device, given 10 times without contact for 16.67 minutes each across 10 days during the winter months, with attack counts kept in a diary and severity rated on a scale. Both groups reported fewer and less severe attacks, but according to the trial the laser group improved significantly more on both counts at 6 weeks and again at 3 months, and heat-based imaging after cold exposure improved only in the laser group. The study authors described the treatment as safe and non-invasive.