Infrared lamp: what does the research really say?

All sorts of claims are made about the infrared lamp. That the warmth penetrates centimetres deep, that it repairs your muscles, that it is the same as red light therapy, that it rejuvenates your skin and shortens your cold. This article sets each claim against what the research actually says, with a link to the original publication.

We sell infrared lamps. That is exactly why this piece is written as soberly as possible: a shop that only shows you the favourable half of the literature is of no use to you. So you will also find here what has not been shown, which popular numbers do not survive the research, and where the real risk lies. The same story for the other two devices is in the article on what the research shows about red light therapy and the one on the infrared sauna and the sauna blanket.

Three devices that are constantly mixed up

This is the most important paragraph of the whole article: most of the research referred to in adverts for infrared lamps is about a different device from the one being sold. There are three kinds, and they differ fundamentally.

The difference is not cosmetic. An LED panel is designed specifically not to warm you up, a heat lamp is designed to do exactly that. Anyone who uses research on one as evidence for the other skips a step that concerns the entire mechanism of action. The difference between the wavelengths is explained in more detail in the article on wavelengths in red light and infrared.

What really comes out of a heat lamp

To follow the rest of this article, you need three terms. The international convention divides infrared into three bands: IR-A from 780 to 1400 nanometres, IR-B from 1400 to 3000 nanometres, and IR-C above that (CIE, International Lighting Vocabulary). Only IR-A gets through the skin to any noticeable degree. IR-B and IR-C are absorbed almost immediately in the top layer and turn into heat there.

An ordinary infrared lamp is an incandescent bulb with a reflector. The filament reaches roughly 2400 to 2500 kelvin and the peak of the radiation then lies around 1200 nanometres. Philips writes in its own technical brochure that about 90 percent of the energy is emitted as infrared heat (Philips, technical information on infrared lamps).

The number that really matters comes from wound care. Researchers working with water filtered infrared had to write down how their device differs from an ordinary heater. Their figure: a conventional infrared heater without a water filter emits 50 to 80 percent of its energy as IR-B and IR-C, while their own device emits less than 0.5 percent of it (Hoffmann, Hartel and Mercer, 2016). In other words: of what comes out of an ordinary heat lamp, most of it gets stuck in the top layers of skin as surface heat.

The depth of 5 to 7 centimetres does not exist

This is the most common inaccuracy in this whole product category, and it is easy to check.

• The scientific committee of the European Commission published an overview of light penetration into the skin. At 1200 nanometres, exactly the peak of a heat lamp, only 1 percent of the light remains at a depth of 0.8 millimetres (SCENIHR, Health Effects of Artificial Light, 2012).
• A calculation using the most favourable assumptions arrived at a maximum penetration of 5378 micrometres, so 5.4 millimetres. The authors themselves add that their method probably overestimates the real values (Ash et al., 2017).
• A modelling study that calculated across the whole spectrum found that penetration increases from ultraviolet to visible light, and then decreases again in the infrared, because water in the tissue absorbs the light (Finlayson et al., 2022).
• The international commission on non ionising radiation keeps it simple: IR-A penetrates the skin a few millimetres, IR-C is absorbed at the surface (ICNIRP on infrared).

Nobody measures the same thing, because "penetration depth" is not a single, clear concept: one person measures where 1 percent of the light remains, another counts scattered light as well. But even the most generous definition comes out at about half a centimetre. Five to seven centimetres is therefore nine to thirteen times off.

The warmth does go deep, but the light does not. Those are two different things.

Because that is the nuance that makes the honest story complete. You really do feel the warmth deeper than half a millimetre. That is not because the radiation gets there, but because the warmed skin passes its heat on through conduction and through the blood flowing through it. The effect is real. The explanation sold with it is simply wrong.

What warmth does in your skin, and where it stops

This part is uncontroversial and well measured. Warmth on the skin opens up the blood vessels. At rest, about 250 millilitres of blood per minute flows through the skin; with substantial warming of the whole body that can rise to 6 to 8 litres per minute (Charkoudian, 2003).

Local warming does the same on a small scale. When researchers kept a patch of forearm at 42 degrees for fifty minutes, blood flow there rose to about 81 percent of the maximum level. At 38 degrees it stayed around 53 percent. The pattern is the same every time: first a rapid peak through a nerve reflex, then a short dip, then a slow rise to a plateau (Mack, Foote and Nelson, 2016).

Up to this point, everything can be demonstrated. The step taken next in almost every product description cannot. Going from "more blood flow" to "heals injuries", "flushes out waste products" or "repairs muscles faster" is a leap with no research beneath it. More blood through the skin is not the same as a muscle underneath recovering faster.

Luxyor Redlight 160

• 275 watt heat lamp on a stand with wheels, so you can aim it at the right spot
• Lamp head fully adjustable via a flexible arm, with protective grille
• Adjustable temperature, recommended use 15 to 30 minutes at 30 to 50 centimetres
• 60 days to change your mind and 2 year warranty

View the Redlight 160

By application: what the research shows

Now the clinical side. We go through the uses people buy an infrared lamp for, and for each one say how strong the evidence is.

Lower back pain: the strongest point, with three caveats

This is the best supported use of warmth, and the support is modest. A Cochrane review of nine studies with a total of 1,117 participants found moderate evidence that heat therapy gives a small, short term reduction in pain and disability in people with acute and subacute lower back pain. The effect after five days was 1.06 points on a scale of 0 to 5, with a confidence interval of 0.68 to 1.45 (French et al., 2006). The American College of Physicians adopted this as a strong recommendation: for acute and subacute back pain, start with superficial heat, massage, acupuncture or manipulation (Qaseem et al., ACP guideline 2017).

The three caveats belong in the same paragraph, not tucked away somewhere at the bottom.

• It is about heat wraps, not a lamp. The studies used patches and wraps worn on the skin for hours at a time at about 40 degrees. A lamp at 40 centimetres for a quarter of an hour is a different exposure.
• It does not apply to chronic back pain. The same ACP guideline deliberately does not mention warmth for chronic back pain. There, it lists exercise therapy, rehabilitation and behavioural treatments.
• The review is from 2006 and has never been updated. That is twenty years ago.

And on the Dutch side: the Dutch GP guideline on non specific lower back pain does not mention warmth at all. The approach there is information, gradually building up activity and exercise therapy (NHG guideline on non specific lower back pain).

Neck: here the verdict is plainly negative

This verdict comes from the Dutch physiotherapy guideline and it is the sharpest one we came across: there is a moderate level of evidence that infrared and warmth in the form of hot packs work no better than a sham treatment for neck pain in reducing pain and improving function (KNGF guideline on neck pain, rationale and explanation, 2016). The working group advises against electrotherapy for neck pain.

The research behind it points the same way. In a double blind study with 48 people with long term neck pain, both the treated group and the sham group improved, with no difference between the two (Lai et al., 2014). The Cochrane review on electrotherapy for neck pain, in which infrared appears as a comparison treatment, looked at twenty small studies and concluded that the low quality of the evidence made it impossible to draw a conclusion (Kroeling et al., 2013).

Osteoarthritis and rheumatism: comfort, not treatment

The only Cochrane review on warmth for knee osteoarthritis included three studies with a total of 179 patients. Hot packs gave no proven benefit; ice massage actually did better on some outcomes (Brosseau et al., 2003). For rheumatoid arthritis, seven studies with 328 participants, the conclusion is that superficial heat and cold can be used as a palliative treatment, in other words to relieve symptoms (Welch et al., 2002).

There is one study that used a real Philips infrared lamp for knee osteoarthritis, and it is instructive for a different reason. Sixty participants received, for twelve weeks, either a combination of ultrasound and interferential current, or infrared alone at 60 centimetres, a quarter of an hour each time. The infrared group did significantly worse than the combination group (Usman, Maharaj and Kaka, 2019). There was no control group and no sham treatment, so the study does not show that infrared works. It shows that infrared alone falls short of an active treatment.

Muscles and sports recovery: the misunderstanding lies in what exactly improves

For muscle soreness after exertion there is a network meta analysis of 59 randomised studies with 1,367 participants. Within the first 24 and 48 hours, the hot pack scored best on perceived pain, after which cold took over (Wang et al., 2022). Note two things: it is about hot packs lying on the skin, not radiation, and it is about how bad the muscle soreness feels, not how quickly the muscle recovers.

On that second point, the systematic review on infrared for musculoskeletal complaints is explicit: infrared has not succeeded in promoting muscle recovery after sports injuries, and infrared clothing gave athletes no benefit at all on muscle damage within 72 hours (Tsagkaris et al., 2022). The blood values that measure muscle damage do not improve, and strength does not come back any faster.

The study web shops like to wave around

Search for "infrared back pain research" and you almost always end up at the same publication. Forty people with chronic lower back pain, seven weekly sessions, and the pain score fell in the treated group from 6.9 to 3.0, against 7.4 to 6.0 in the sham group (Gale, Rothbart and Li, 2006). That sounds convincing. There are just four holes in it.

• 39 people were left for the analysis. That is too small to derive a reliable effect from.
• The participants came from the patient lists of a single pain clinic.
• The manufacturer of the device is mentioned by name in the abstract. That is unusual language for a scientific summary.
• The sham treatment was the same device without power. That does not get warm, so every participant knew straight away which group they were in.

Put the largest study in this field next to it. One hundred and forty eight people with chronic lower back pain, twelve sessions over four weeks, followed for up to twelve months. The difference from the sham treatment on pain was 0.01 points, with a confidence interval of minus 0.94 to 0.96. The title could not be clearer: photobiomodulation is no better than a sham treatment (Guimarães et al., 2021). That study used laser and LED, so no heat radiation. But it does refute the claim that infrared light cures chronic back pain.

The problem that haunts this whole field

There is a reason why research on warmth is so hard to pin down, and it is fundamental: you cannot blind warmth. With a pill, half the group gets a dummy version and nobody knows who got what. With warmth, every participant feels straight away whether they are being warmed. Everything people then report themselves about pain, stiffness or fatigue is therefore partly coloured by expectation.

The review on infrared for musculoskeletal complaints says it literally: blinding these studies remains difficult, because participants realise which group they are in (Tsagkaris et al., 2022). A large analysis of 194 publications on sham treatments in pain studies found that with non drug treatments, participants are actually blinded in less than a quarter of studies, and that whether the blinding worked is almost never reported (Hohenschurz-Schmidt et al., 2023).

What does that mean for you? That with warmth, "it helps me" and "the remedy works" can never be fully separated. That is no reason not to use a heat lamp. It is the reason we do not attach any healing claims to it.

Three claims that do not make it

These three are the ones you come across most often with infrared lamps. We checked all three against the literature.

Claim 1: it helps with colds and blocked sinuses

We searched specifically for this. There is not a single randomised study in which an infrared heat lamp was tested for a cold, a blocked nose or sinusitis. What does exist concerns the closest principle that has been studied: heated, humidified air. Cochrane looked at six studies with 387 participants and concluded that no benefit and no harm has been shown, with low quality evidence (Singh et al., 2017).

In a British study in general practice with 871 people with long lasting nose and sinus complaints, steam inhalation only reduced headache and nothing else (Little et al., 2016). The Dutch public health site Thuisarts.nl puts it just as soberly: steam inhalation does not make you better any faster, but it can ease your symptoms (Thuisarts.nl, I have a cold).

Verdict: insufficiently studied, and the mechanism does not fit. A heat lamp does not produce moist air. Warmth on your face can feel nice when you have a cold, but it does not shorten a cold and it does not open up your sinuses.

Claim 2: it builds collagen and rejuvenates your skin

Here things are exactly the other way round from what the advertising suggests, and this is the part you read least often.

The study web shops routinely cite for skin improvement used 136 volunteers and panels with an intensity of 5.9 to 13.3 milliwatts per square centimetre. In the abstract the researchers literally call their treatment non thermal photobiomodulation, and the research was paid for in full by a manufacturer of light equipment (Wunsch and Matuschka, 2014). A heat lamp whose entire effect rests on noticeable warmth is by definition not a non thermal treatment. The international definition of photobiomodulation says so in as many words (Anders, Lanzafame and Arany, 2015).

There is also research pointing the other way. In people repeatedly exposed to infrared, three times a week for four weeks, the production of type I collagen fell and the enzyme that breaks down collagen rose. With a single exposure, the opposite happened (Kim et al., 2006). In another study, 80 percent of participants responded to IR-A with an increase in that same breakdown enzyme, and the amount of antioxidants in the skin fell measurably (Schroeder et al., 2008). Warmth alone, separate from the radiation, does something similar (Cho et al., 2009).

To be fair: that picture is disputed. A methodological review showed that many of these studies did not keep sufficient track of the radiation dose and the heat exchange (Piazena and Kelleher, 2010). Others point out that glass and steel workers show little chronic skin damage despite years of high infrared exposure, and that it is therefore premature to put infrared filters in sunscreen (Diffey and Cadars, 2016). And according to ICNIRP, infrared plays no role in the development of skin cancer.

Verdict: not applicable, and possibly counterproductive. The debate among experts is about infrared at sunlight level. Nobody in that debate argues for aiming a concentrated heat source at the same patch of face every day. Do not aim a heat lamp at your face.

Claim 3: cellulite, detoxing and a stronger immune system

These three can be brief.

• Cellulite. The only systematic review on this topic looked at 67 publications and concludes literally that for none of the cellulite treatments studied could clear evidence of good effectiveness be found (Luebberding, Krueger and Sadick, 2015).
• Detoxing. That claim rests entirely on sweating, and a local lamp on your shoulder will hardly make you sweat. Why it does not hold up for whole body warmth either is explained in the article on the infrared sauna and the research.
• Immune system. The only starting point is a 1990 study with fifty participants, on sauna, so on the whole body, without blinding and never convincingly repeated (Ernst et al., 1990). Nothing about a lamp on one spot can be derived from it.

Strong infrared research does exist, but not about your lamp

This is the most interesting part of the file, and almost no web shop tells you about it. There really is convincing clinical research with infrared A, it is just about a different device.

Water filtered infrared A passes the light of a halogen lamp through a cuvette of water. Water absorbs exactly the bands that would otherwise heat the skin superficially, around 970, 1197 and 1400 nanometres. What remains is narrowband infrared A that gets further (Piazena, Müller and Vaupel, 2022).

The results are serious. In 111 patients after abdominal surgery, irradiation after the operation gave better wound healing, less pain and a higher oxygen tension in the tissue (Hartel et al., 2006). In a study of 400 patients, a single twenty minute irradiation before the operation halved the number of wound infections, from 12.1 to 5.1 percent (Künzli et al., 2013). In chronic leg ulcers, the wounds closed on average in 14 instead of 42 days (Hoffmann, Hartel and Mercer, 2016).

And then the sentence that explains why you may not extend this to a household lamp, from that same review: a filtered heater emits less than 0.5 percent IR-B and IR-C, compared with 50 to 80 percent for a conventional heater without a water filter, and at the same skin temperature the filtered version delivers four to nine times as much usable IR-A. Researchers who worked with both measured that conventional infrared gives a hotter skin and a cooler depth, and filtered infrared exactly the opposite (Hoffmann, 2009).

In other words: an ordinary heat lamp has to put four to nine times as much heat on your skin to achieve the same at depth. That is not a detail. It is both the reason the results above do not apply to a lamp from the shop, and the reason the skin has more to endure with an ordinary lamp.

Safety: this is the part that does matter

The health gains are open to debate. The risks much less so, and they are easy to manage once you know where they lie.

The eyes are the real point of attention

With bright visible light you automatically squeeze your eyes shut. With infrared that does not happen, because there is hardly any visual stimulus. The international radiation commission writes that the absence of that stimulus removes the protective reaction, and that you therefore cannot assume your pupil will narrow (ICNIRP guideline, Health Physics 2013). The warmth on your cornea does warn you, but your lens and retina feel nothing.

That same guideline gives the exposure limits for the eye, and they get stricter the longer you look: 3,200 watts per square metre is allowed for ten seconds, 569 for a hundred seconds, and from about seventeen minutes only 100 watts per square metre. The longer the session, the further away you need to be.

That infrared can damage the lens of the eye is not a theory. It is the classic occupational risk of glassblowers and furnace workers. In a Swedish study of 209 glass workers with at least twenty years of exposure, compared with 298 controls, the risk of vision loss from cataract in the over seventies group was 2.5 times higher and the risk of cataract surgery twelve times higher (Lydahl and Philipson, 1984). Modern research shows that this damage is thermal and not photochemical (Söderberg et al., 2016).

Do keep that in proportion: these were people who worked in intense radiation every day for twenty years or more. A quarter of an hour at home is something very different. But it is exactly why every manufacturer writes the same thing: do not look into the lamp and keep your eyes closed. Philips puts it like this: do not look directly into the lamp while it is on and keep your eyes closed. Why good glasses are pleasant to use with it is explained in the article on red light glasses.

Distance and time: the only number that counts is in your manual

Look at what manufacturers prescribe, and you will see straight away that wattage says nothing.

A 100 watt lamp here requires more distance than a 200 watt one. That is because the reflector, the filter and the beam angle determine how much radiation arrives per square centimetre, not the power consumed. The conclusion is simple: never copy the distance of one lamp for another. Only the manual of your own device counts.

Why that distance matters so much is simple physics. The intensity decreases with the square of the distance. If you go from 40 to 20 centimetres, you do not get twice but four times as much warmth on your skin. That is exactly the mistake people make when they "do not feel anything" and move closer.

Because the margin is small. Pain arises in human skin just above 43 degrees, and as soon as the bottom layer of the epidermis reaches 44 degrees, tissue damage occurs (Martin and Falder, 2017). So there is about one degree between pleasantly warm and damaging. That is why every manufacturer's rule is so strict: the warmth must stay comfortable for the whole session, and never fall asleep with the lamp on.

Erythema ab igne: the damage that creeps up on you

This is the risk people do not see coming, because no burn is involved. Repeated warmth on the same spot, just below the burn threshold and usually below 45 degrees, can cause a net like reddish brown discolouration of the skin. It develops over weeks to years. The discolouration can fade after months to years, but permanent pigmentation or scarring does occur (Erythema ab igne, StatPearls, 2025). In rare cases, malignant change has been described (Wilder, Frieder and Menter, 2021).

The documented cases involve hot water bottles, heaters, heating pads and laptops. We found no case series that attributes this specifically to therapy lamps. The mechanism, however, is exactly the same. So vary the spot, do not use the same setting on the same patch of skin for half an hour every day, and have a lasting discolouration assessed.

Who should be careful or check first

This list comes largely from the manufacturer itself, which makes it hard to argue with. Philips writes that you should not use an infrared lamp (Philips on when not to use InfraCare):

• If you do not feel warmth properly. With advanced diabetes, nerve damage or the use of painkillers, the warning that normally protects you is missing. This is the most important point on the whole list.
• With disturbed temperature regulation or poor circulation. The same problem, a different cause.
• With serious conditions without consulting your doctor: heart conditions, acute inflammatory diseases, thrombosis, clotting disorders.
• With swelling or inflammation, because warmth can actually make the symptoms worse, and with oedema.
• With conditions involving nerve damage such as carpal tunnel syndrome or multiple sclerosis, and with implants in or near the area.
• During pregnancy: not on or close to the belly.
• Not on damaged or irritated skin, on wounds, or on skin that has just had a cream applied, for example one with menthol.

Two groups deserve extra attention. Older people feel warmth less well and sweat less, and medication can reinforce that (RIVM, risk groups in hot weather, 2023). And children: in an analysis of 447 burns caused by heat sources at home, 43 percent were younger than five (Brewer et al., 2021). A lamp that is switched on should not be left unattended in a room with small children.

One misunderstanding we do want to correct: sensitivity to light caused by medication, as with certain antibiotics and water tablets, is a problem of ultraviolet and visible light, not of infrared (DermNet, drug induced photosensitivity). With a heat lamp, the issue is not phototoxicity but a dulled sense of warmth.

Fire and placement

A heat lamp is a heat source of hundreds of watts. In stables and barns, heating appliances are the main cause of fire, and heat lamps are the biggest culprit among them (Rutgers, Fire Prevention and Safety Measures Around the Farm, 2019). In practice that means: keep at least a metre of clear space from flammable items such as curtains, blankets and paper, place the lamp securely so it cannot fall over, never cover it, plug it directly into the wall socket instead of an extension reel, and switch it off after use.

How to recognise a good lamp

What really tells you something: a manual in your own language that states a concrete distance, a maximum time and the contraindications, and a responsible party with an address in the EU. A loose bulb without a manual does not meet that, however cheap it is. More about that difference is in the article on a cheap infrared lamp or a therapy lamp on a stand.

What we do and do not conclude from this

We sell infrared lamps. Based on everything above, this is what we say about them.

Luxyor Redlight 120

• Compact 275 watt heat lamp for targeted use on one spot
• Adjustable, so you can aim the warmth at your shoulder, back or knee
• Meant for short sessions, not for hours on end
• 60 days to change your mind and 2 year warranty

View the Redlight 120

What we do not say: that a heat lamp penetrates five to seven centimetres deep, that it is the same as red light therapy, that it rejuvenates your skin, detoxes you, strengthens your immune system, shortens your cold or treats a condition. The research cannot support that, and some of it even points the other way.

What we do say: an infrared lamp gives targeted, pleasant warmth on one spot. Blood flow in the skin demonstrably increases. For acute lower back pain, warmth is one of the few self care options included in a guideline. For muscle soreness after exercise, the research shows that warmth eases perceived pain in the first days, although that was measured with hot packs and not with a lamp. And, perhaps the most down to earth argument of all: warmth lowers the barrier to getting moving again, and movement is what every guideline recommends for back problems. The lamp is a stepping stone, not a replacement.

We will tell you the weak point of that answer straight away. Finding warmth pleasant is subjective, the effect is largely temporary, and with warmth it is never possible to separate exactly what the warmth does and what the expectation does. That is why we offer 60 days to change your mind, so you can try it out in your own home instead of having to take our word for it.

What to watch out for in claims about infrared lamps

With the above, you will recognise most nonsense straight away. These are the patterns you come across most often.

• A depth in centimetres. Five to seven centimetres, sometimes even ten. The highest calculated number in the literature is half a centimetre, and that is probably already too high.
• Red light research used for a heat lamp. Studies with LED panels of 5 to 15 milliwatts per square centimetre say nothing about a lamp that does its job with noticeable warmth.
• Wavelengths of 660 and 850 nanometres on the box of an incandescent bulb. A filament emits a broad spectrum with a peak around 1200 nanometres. Individual numbers suggest a precision that is not there.
• Research on water filtered infrared as support. That is a different device, with more than 99 percent of the superficial bands filtered out.
• Detoxing. As soon as that word comes up, you know enough. A lamp on your shoulder will not even make you sweat.
• Collagen and skin rejuvenation. Not supported for this device, and there is research pointing the other way.
• A study with forty participants as proof. That happens all the time, and it is almost always the same publication from 2006.
• No source at all. "Scientifically proven" without saying which study, how many people and which device is a slogan.
• No distance and no time. A seller who does not tell you at how many centimetres and for how long to use the lamp leaves out the most important part.

In conclusion

The honest state of affairs is this. An infrared lamp warms the top millimetres of your skin, and from there the warmth spreads further through conduction and blood flow. The evidence for pain relief is narrow, short term and comes largely from heat wraps rather than lamps. For neck pain, the Dutch guideline says it is no better than a sham treatment. The convincing infrared research that does exist is about a filtered device in hospital.

That is less than what you read elsewhere, and it is exactly what it is. A heat lamp is not a medical device and not a miracle cure. It is a simple, pleasant way to warm a spot on your body, with a few clear rules about distance, time and your eyes. Want to look further? You will find the models among the infrared lamps, and practical guidelines in the guide to using an infrared lamp.

Sources

All sources below are peer reviewed publications, official guidelines or standards. The links go straight to the original, so you can check everything yourself.

1. CIE (2020). Infrared radiation, term 17-21-004. International Lighting Vocabulary, CIE S 017:2020. cie.co.at
2. ICNIRP. Infrared radiation (780 nm to 1 mm), topic page. icnirp.org
3. ICNIRP (2013). Guidelines on Limits of Exposure to Incoherent Visible and Infrared Radiation. Health Physics 105(1):74-96. icnirp.org (pdf)
4. Philips Lighting (2007). Technical information and support facilities, Philips infrared lamps. prolight.info (pdf)
5. SCENIHR, European Commission (2012). Health Effects of Artificial Light, sections 3.4.1 and 3.4.2. ec.europa.eu (pdf)
6. Ash C, Dubec M, Donne K, Bashford T (2017). Effect of wavelength and beam width on penetration in light-tissue interaction using computational methods. Lasers in Medical Science 32(8):1909-1918. PMCID PMC5653719
7. Finlayson L, Barnard IRM, McMillan L, et al. (2022). Depth Penetration of Light into Skin as a Function of Wavelength from 200 to 1000 nm. Photochemistry and Photobiology 98(4):974-981. open access pdf
8. Kaub L, Schmitz C (2023). Comparison of the Penetration Depth of 905 nm and 1064 nm Laser Light in Surface Layers of Biological Tissue Ex Vivo. Biomedicines 11(5):1355. doi:10.3390/biomedicines11051355
9. Charkoudian N (2003). Skin blood flow in adult human thermoregulation: how it works, when it does not, and why. Mayo Clinic Proceedings 78(5):603-612. mayoclinicproceedings.org
10. Mack GW, Foote KM, Nelson WB (2016). Cutaneous Vasodilation during Local Heating: Role of Local Cutaneous Thermosensation. Frontiers in Physiology 7:622. doi:10.3389/fphys.2016.00622
11. French SD, Cameron M, Walker BF, Reggars JW, Esterman AJ (2006). Superficial heat or cold for low back pain. Cochrane Database of Systematic Reviews CD004750. cochrane.org
12. Qaseem A, Wilt TJ, McLean RM, Forciea MA (2017). Noninvasive Treatments for Acute, Subacute, and Chronic Low Back Pain: A Clinical Practice Guideline From the American College of Physicians. Annals of Internal Medicine 166(7):514-530. full text (pdf)
13. NHG (Dutch College of General Practitioners). Guideline on non specific lower back pain (in Dutch). richtlijnen.nhg.org
14. KNGF (2016). Royal Dutch Society for Physical Therapy guideline on neck pain, rationale and explanation, section C.1.3 Electrotherapy (in Dutch). pdf
15. Lai CH, Leung TK, Peng CW, et al. (2014). Effects of far-infrared irradiation on myofascial neck pain: a randomized, double-blind, placebo-controlled pilot study. Journal of Alternative and Complementary Medicine 20(2):123-129. doi:10.1089/acm.2013.0122
16. Kroeling P, Gross A, Graham N, et al. (2013). Electrotherapy for neck pain. Cochrane Database of Systematic Reviews CD004251. cochrane.org
17. Brosseau L, Yonge K, Welch V, et al. (2003). Thermotherapy for treatment of osteoarthritis. Cochrane Database of Systematic Reviews CD004522. cochrane.org
18. Welch V, Brosseau L, Casimiro L, et al. (2002). Thermotherapy for treating rheumatoid arthritis. Cochrane Database of Systematic Reviews CD002826. cochrane.org
19. Usman Z, Maharaj SS, Kaka B (2019). Effects of combination therapy and infrared radiation on pain, physical function, and quality of life in subjects with knee osteoarthritis. Hong Kong Physiotherapy Journal 39(2):133-142. full text
20. Wang Y, Lu H, Li S, et al. (2022). Effect of cold and heat therapies on pain relief in patients with delayed onset muscle soreness: A network meta-analysis. Journal of Rehabilitation Medicine 54:jrm00258. doaj.org
21. Tsagkaris C, Papazoglou AS, Eleftheriades A, et al. (2022). Infrared Radiation in the Management of Musculoskeletal Conditions and Chronic Pain: A Systematic Review. European Journal of Investigation in Health, Psychology and Education 12(3):334-343. doi:10.3390/ejihpe12030024
22. Gale GD, Rothbart PJ, Li Y (2006). Infrared therapy for chronic low back pain: a randomized, controlled trial. Pain Research and Management 11(3):193-196. PMID 16960636
23. Guimarães LS, Costa LCM, Araujo AC, et al. (2021). Photobiomodulation therapy is not better than placebo in patients with chronic nonspecific low back pain: a randomised placebo-controlled trial. Pain 162(6):1612-1620. PMID 33449509
24. Hohenschurz-Schmidt D, Draper-Rodi J, Vase L, et al. (2023). Blinding and sham control methods in trials of physical, psychological, and self-management interventions for pain (article II). PAIN 164(3). full text (pdf)
25. Singh M, Singh M, Jaiswal N, Chauhan A (2017). Heated, humidified air for the common cold. Cochrane Database of Systematic Reviews CD001728. cochrane.org
26. Little P, Stuart B, Mullee M, et al. (2016). Effectiveness of steam inhalation and nasal irrigation for chronic or recurrent sinus symptoms in primary care. CMAJ 188(13):940-949. doi:10.1503/cmaj.160362
27. Thuisarts.nl (NHG). I have a cold (in Dutch). thuisarts.nl
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