Does red light help wounds heal? It depends on the wound

The short answer

"Red light helps wounds heal" is true and false at the same time, and which one depends on the wound. This is the wound chapter of our wider read of the red and infrared light literature.

In diabetic foot ulcers it nearly doubles the chance of healing. In venous leg ulcers, a wound that looks similar from the outside and sits in the same place, it demonstrably does nothing. That is not sloppiness in the research. It is the research telling you something the marketing leaves out: wound healing is not one outcome.

Which wounds does red light actually heal?

A risk ratio of 1.93 means the treated group healed nearly twice as often. For this condition that is a large effect, and it is the best supported use of light on a wound there is.

In radiation dermatitis, the skin damage that develops during radiotherapy for cancer, a meta-analysis of five studies found that people treated with light beforehand developed less severe skin reactions, with fewer interruptions of their radiotherapy ^[3]. The authors call it protective but ask for larger studies before it is settled.

Where does red light do nothing?

And then the wound that most resembles it.

Why does the research on burns contradict itself?

In burns, two meta-analyses reach opposite conclusions.

The first, from 2021, found light favourable for wound contraction and blood vessel formation, at moderate certainty ^[4]. The second, from 2025 and considerably larger at 51 studies, found light not statistically effective for wound contraction or collagen production ^[5].

An important detail: both lean heavily on animal work. In burns the human clinical literature is thin, and that in itself answers the question of whether to point a lamp at a burn.

Why are the reviews so hard to compare?

There is an explanation for all that contradiction, and it lies not in the wounds but in the measuring.

An audit of the literature examined how researchers report their light dose, and the finding is uncomfortable: measuring and recording power, wavelength, irradiated area and actual dose is done poorly and inconsistently ^[6]. The title of that paper is not an accident: "the dark art of light measurement".

Without those numbers nobody can repeat a study, and two meta-analyses claiming to examine the same intervention may in fact be about different treatments. That is a plausible explanation for why this field produces so many reviews that contradict each other.

What we think

If somebody tells you red light heals wounds, ask which wound.

For diabetic foot ulcers the answer is clearest and most positive, and that is also the use hospitals have adopted. For venous leg ulcers the best available evidence says it adds nothing. For burns the reviews disagree and the work is largely in animals.

And for the ordinary cut or graze at home, which none of these studies is about: nothing has been studied, and it heals anyway.