When a wound heals nicely, you hardly notice the process. When healing is prolonged, or when a scar becomes stiff, red, and bothersome, you quickly become curious about methods that can support the body without further irritating the skin.

Red and near-infrared light therapy (photobiomodulation, PBM) is one of the technologies that has received more attention in recent years in both clinics and for home use. The question is: What is the actual evidence, and where does it make the most sense to set expectations?

What happens when a wound heals?

Wound healing typically occurs in phases that overlap:

First comes the inflammation phase, where the body cleans up and protects against infection. This is followed by the proliferation phase, where new skin cells, connective tissue, and small blood vessels are formed. Finally comes the remodeling phase, where collagen fibers are reorganized, and scar tissue gradually becomes more flexible.

A scar is not just “a spot.” It is a tissue where collagen is arranged differently than in normal skin, and where blood flow, tension in the tissue, and inflammation can affect appearance and sensation for a long time.

What is red and near-infrared photobiomodulation?

PBM is light therapy with relatively low energy levels, where red light (approx. 600–700 nm) and near-infrared light (approx. 700–1100 nm) are absorbed in cells, especially in the mitochondria. A central mechanism in the literature is the influence on the enzyme cytochrome c oxidase, which can lead to increased ATP production and altered cell signaling.

In the context of wounds, research especially points to four biological tracks:

• increased cell activity (keratinocytes and fibroblasts), which can support closure and reconstruction
• influence on collagen and matrix formation (ECM)
• regulation of inflammation (typically a shift towards less pro-inflammatory signaling)
• influence on microcirculation and angiogenesis, including via VEGF- and NO-related mechanisms

It is also important that PBM is not “the more, the better.” Many studies describe a biphasic dose response, where low to moderate doses can support healing, while very high doses can give less effect or in some cases inhibit the process.

Evidence for wound healing: what do the studies show overall?

The evidence is mixed, but not random. When looking across preclinical studies, systematic reviews, and randomized trials, some patterns emerge.

Preclinical data (cell and animal studies) are often clear: red/near-infrared light can increase migration and proliferation of skin-relevant cells, affect collagen structure, and support faster wound closure in controlled models. This type of study cannot alone prove clinical effect in humans, but they explain why effects are biologically plausible.

In clinical studies, the effect is more often dependent on wound type, protocol, and patient group. Oral wounds after dental surgery have in several RCTs and in a systematic review shown faster healing with low-energy laser (LLLT) compared to control. Diabetic foot ulcers are another area where meta-analyses often find better healing rates when PBM is added to standard wound treatment.

Then there are studies that do not find a clear difference. A Danish double-blinded RCT on pressure ulcers category 2 found no significant extra effect of LED treatment compared to sham. And a small RCT on surgical leg ulcers also did not show certain improvement. These kinds of results are important because they remind us that PBM is not a guarantee, and that protocol and wound biology can “eat” the effect.

Below is a practical overview of where the evidence is typically assessed as stronger or weaker when reading the literature as a whole.

Scar tissue and remodeling: what is realistic?

When a wound is closed, the tissue continues to change for months. This is where scar tissue can become more or less visible and more or less flexible. PBM is often used with the hope of:

• less redness and irritation
• softer and more pliable scar
• better comfort with tightening and “pulling” in the skin

Clinical data on scar tissue are still relatively few compared to the pain and muscle area. A split-face phase II trial after facial surgery did not necessarily show significant improvement on the primary measurement of scar flexibility, but there were tendencies and improvements in individual assessments over time at certain doses. This is a typical pattern: some parameters move, others do not, and timing and dose seem to matter a lot.

A scar can also be “mechanically dominated.” If the tissue is constantly under tension, or if there is reduced mobility in underlying tissue, manual scar mobilization, load management, and time may be at least as crucial as light.

Why are the results mixed?

There are several recurring explanations in the literature, and they are rarely about “light works” or “light does not work.” They are about when and how.

Many studies differ on parameters that are difficult to compare directly, and therefore two studies on paper may look similar, but are actually very different.

• Short distance to the skin
• Uneven treatment frequency
• Differences between LED and laser
• Simultaneous standard treatment (offloading, wound changes, signs of infection)

And in wound treatment, the context is crucial:

• Wound type: Acute incision, chronic wound, diabetic wound, and pressure ulcer are biologically different issues.
• Dose and “biphasic response”: Too low a dose may be too weak, too high a dose may give less effect.
• Timing: Some protocols start early, others only after days or weeks, where the wound environment is already locked in a bad phase.
• Measurement method: Wound area, time to closure, pain, tissue thickness, and cosmetic score do not tell the same story.

Protocol in practice: what often recurs

There is no one universal standard, but several patterns recur in studies that report effect: repeated treatments, relatively short sessions, and an overall treatment period over weeks.

If you use PBM as a supplement, you should think in terms of a plan that is easy to follow and that does not irritate the tissue.

• Frequency: 3 to 5 times a week for a period (often 2 to 6 weeks)
• Duration: typically minutes, not “as long as possible”
• Target area: the entire wound edge and tissue around, not just the middle
• Documentation: photo, measurement of area, and note of pain/tenderness can make it easier to assess whether something is changing

In wounds and scars, it is also worth remembering that PBM rarely stands alone.

• Wound hygiene and bandages: correct wound care is still the foundation.
• Offloading: especially for foot ulcers and pressure ulcers.
• Nutrition and disease control: protein, iron status, diabetes regulation, and smoking can move more than a single technology.

Safety and when to be extra careful

Red and near-infrared PBM is described in many studies as gentle, with few and mild side effects such as transient redness and rarely irritation at high doses. Nevertheless, it makes sense to have clear safety frameworks.

• Eyes: use protection, and never shine directly into the eye.
• Known cancer in the area: avoid radiation, unless a doctor has made a decision.
• Photosensitive medicine: talk to your therapist if you react strongly to light or get a rash.
• Signs of infection: heat, increasing pain, pus, fever, or bad odor require assessment before continuing.

An open wound that does not get smaller over time should be assessed by a healthcare professional. PBM can be a supplement, but it must not delay relevant treatment.

Choice of equipment: quality, CE, and use in the home

When PBM moves into private homes, equipment selection suddenly becomes part of the “evidence in practice.” There can be a big difference in whether a device delivers stable wavelength and appropriate intensity, and whether it is documented and produced under orderly conditions.

In Denmark, many choose to look for:

• CE marking (and preferably clear classification as medical equipment if it is marketed for treatment)
• clear specifications on wavelength (nm), power, and recommended distance
• safety accessories, especially eye protection for powerful units
• access to guidance in Danish and the possibility of support

Heat Sense is an example of a Danish player that sells CE-approved light therapy and laser therapy units for both private and professional use, with fast delivery from stock in Denmark. This type of setup can be practical when you want clear manuals, spare parts, and a fixed contact if you are in doubt about use and safety.

It just does not change the central point: The effect on wounds and scar tissue still depends on correct dosage, wound type, and the overall treatment course. The most useful question is often not “which lamp is best?”, but “how do I fit PBM into a course where wound care, offloading, and control of irritation are also in place?”.

When PBM makes the most sense as a supplement

PBM typically becomes most relevant when there is a clear objective, and when you can follow the development over time, without changing too many other things at the same time.

It can be in case of slow healing, in case of wounds that have difficulty moving on from inflammation, or when a scar is closed but still red and tight, and you want to support the remodeling in combination with good skin care and gradual mobilization.

And sometimes the most professional choice is to stop, adjust the dose, or get a wound nurse or doctor involved before continuing.