Can Red Light Therapy Relieve Itching? What a Randomized Trial Found

Itch might seem like a minor complaint, but chronic itching from skin conditions and allergic reactions can seriously affect quality of life — and this trial offers a genuinely nuanced look at when light therapy does and doesn't help.

What the research looked at

Published in PLOS ONE in 2024, this double-blind, randomized, sham-controlled, split-body study enrolled 17 healthy volunteers. Researchers induced itching on each participant's skin using two different methods: histamine (the most common itch-triggering chemical, involved in allergic reactions) and Mucuna pruriens (a plant-based itch trigger that works through a different, non-histamine pathway). One side of the body received real low-level light therapy and the other received a sham treatment, allowing a direct within-person comparison. Researchers measured itch intensity, plus two related sensitivities: alloknesis (itch triggered by normally non-itchy touch) and hyperknesis (exaggerated itch from a mildly itchy stimulus).

What they found

For histamine-induced itch, light therapy significantly reduced itch intensity, alloknesis, and hyperknesis compared to the sham-treated side. For itch induced by Mucuna pruriens, there was no significant difference between light therapy and sham — the treatment didn't help with this non-histamine itch pathway at all.

What this means in practice

This is a small trial (17 participants) in healthy volunteers with experimentally induced itch, not people with a chronic skin condition, so it's early-stage evidence rather than a clinical recommendation. What makes it valuable is the clear, honest pattern: light therapy worked specifically through the histamine pathway and didn't work through a different itch mechanism — a useful clue for which real-world itch conditions (allergic reactions, hives, insect bites) it might help with, versus conditions driven by other pathways where it likely wouldn't.