Is Red Light Therapy Hot? What You Should Feel and When to Stop
Is red light therapy hot? No: a session with red and near-infrared LED light should feel mildly warm at most, and measured skin warming in LED studies ranges from no significant change to about 1 to 3°C. Below: what the temperature studies found, why near-infrared and face masks can feel warmer, how light differs from heat lamps, saunas and tanning beds, the signs that mean stop, and how to keep sessions comfortable with our panel and mask.
Key takeaways
- In a thermal camera study of 42 adults with light, medium and dark skin, red and infrared LED and laser light caused no significant rise in skin temperature. Grandinétti, 2015
- In a randomised study of 20 adults, 5 minutes of red or near-infrared LED light over the wrist warmed the skin by about 1 to 3°C in the people who warmed at all. Hoffer, 2020
- Researchers define photobiomodulation as "a nonthermal process involving endogenous chromophores", separate from heating tissue with lamps. Anders, 2015
- The International Commission on Non-Ionizing Radiation Protection (ICNIRP) states that skin normally needs to reach at least 45°C before a thermal burn occurs. ICNIRP, 2013
- The front surface of the Kivorla red light panel stays at or below 40°C, and our rule for any session is short: warm is fine; hot means stop.
Is red light therapy hot?
No, red light therapy is not meant to feel hot, and mild warmth is the most you should notice. Our rule is short: warm is fine; hot means stop.
The research field behind it is called photobiomodulation. A 2015 editorial that set out the standard definition describes it as light from lasers, LEDs or broadband sources in the visible and infrared range, absorbed by molecules inside cells. Anders, 2015 The same authors separate it from "simple heating of tissues", such as warming the body with near-infrared lamps.
"Non-thermal" describes how the light works, not a promise that you feel nothing. Some of any light your skin absorbs ends up as heat, so a gentle warmth on the treated area is common.
The American Academy of Dermatology (AAD) lists "temporary mild pain or irritated skin" as the most common side effects. AAD, 2024 Harvard Health calls them minimal. Harvard Health, 2025
Does red light therapy feel warm on the skin, and by how many degrees?
Yes, it can feel slightly warm, but the measured change is small. Studies have found anything from no significant rise to about 1 to 3°C after 5 minutes of LED light.
The largest study filmed the skin of 42 healthy volunteers with a thermal camera. Grandinétti, 2015 Each had a placebo and three active doses lasting up to about 6 minutes. Skin temperature did not rise significantly in any group by skin colour, age or sex.
A randomised study of 20 adults looked closer. Hoffer, 2020 Red (630 nm) or near-infrared (830 nm) LED light shone over the wrist for 5 minutes while a thermal camera watched the hand. Skin warmed and then levelled off, by about 1°C at the wrist and about 3°C at the fingertips.
Those figures come from the people who responded. Half the volunteers, 10 of 20, warmed by at least 0.5°C. Gavish, 2020 Those whose hands started very warm or very cold did not respond.
| Study | Who | Light | Time | Temperature finding |
|---|---|---|---|---|
| Grandinétti, 2015 | 42 adults, light, medium and dark skin, placebo | 640 nm red LED, 875 nm infrared LED and 905 nm laser, on the skin | 76 to 380 seconds | No significant rise in any group |
| Hoffer and Gavish, 2020 | 20 healthy adults, randomised | 630 nm red or 830 nm near-infrared LED, over the wrist | 5 minutes | About 1 to 3°C in the 10 who responded |
| Wang, 2018 | 11 healthy adults, heat-only comparison | High-power near-infrared laser, forehead | 8 minutes | Copying the warmth with heat alone did not copy the light's effects |
That scale of warming is what we mean by mild warmth.
Why does near-infrared feel warmer than red light?
Near-infrared reaches deeper than red, and in one trial it increased local blood flow while red did not. More blood flow brings more warmth to the skin, so a session heavy in near-infrared can feel a little warmer.
In the wrist trial, 830 nm near-infrared light raised blood flow in the small vessels of the skin, and the rise continued during 20 minutes of follow-up. Gavish, 2020 Red light at 633 nm did not raise the median flow.
ICNIRP describes near-infrared (780 nm to 1.4 µm) as reaching several millimetres, while far infrared is absorbed at the very surface. ICNIRP Far infrared puts its energy into the outer skin, which is why it is mainly felt as heat; our guide to far infrared vs near infrared explains the difference.
- Our mask: both modes include 850 nm near-infrared, and the red mode adds 1064 nm.
- Our panel: four of its nine channels are near-infrared: 810, 830, 850 and 1060 nm.
Is warmth a sign that red light therapy is working?
No. Warmth is a side effect of absorbed light, not the way photobiomodulation works, and more warmth does not mean more benefit.
A lab study in 11 healthy adults tested this directly. Wang, 2018 Researchers used a heat-only device to copy the skin warming produced by a near-infrared laser. Heat alone did not raise the signal from cytochrome c oxidase, the light-absorbing enzyme in mitochondria, while the light did. The authors concluded the light's effects were not caused by skin heating.
Light also follows a biphasic dose response: low levels stimulate, while high levels can hold the effect back. Hamblin, 2017 Our guide on how much red light therapy is too much covers the limits.
Why can an LED face mask feel warm?
A mask sits close to the skin, so you notice the warmth of absorbed light, the near-infrared in both modes, and your own skin heat held under the shell. Mild warmth is normal; if it feels more than mildly warm, lower the brightness or stop.
Our 4-Wavelength Red Light Therapy Mask is a full-face silicone shell with one eye opening. The red mode combines 665 nm red with 850 and 1064 nm near-infrared; the blue mode combines 460 nm blue with 850 nm near-infrared.
- Start low: choose 50% brightness and the 5 or 10 minute timer for the first sessions.
- Skin: clean, dry and cool, so after a sauna or hot shower let your face cool first.
- If it feels too warm: drop to a lower brightness, choose a shorter timer, or take it off.
It switches off when the timer ends. Keep your eyes closed and do not stare into the light.
Does red light feel hotter on darker skin or over tattoos?
It can, because melanin and tattoo ink absorb more light and warm up faster. Our panel is not for Fitzpatrick skin types V or VI, and tattoos are best covered or kept out of the light.
The AAD notes that people with darker skin tones are more sensitive to visible light, and advises talking to a dermatologist before starting. AAD, 2024 Our guide is red light therapy safe explains that skin of colour has a higher risk of lasting redness, discolouration or blistering, and that near-infrared can blister skin over black tattoo ink within seconds.
Short exposures can stay mild across skin tones: the 42-person thermal camera study found no significant rise in any skin colour group, dark skin included. Grandinétti, 2015
How is red light therapy different from a heat lamp, an infrared sauna or a tanning bed?
Heat lamps and infrared saunas are built to heat you, and tanning beds work with ultraviolet (UV) light. Red light therapy devices give off visible red and near-infrared light, produce no UV and are not designed to warm the body.
| Device | Main output | Built to heat? | Typical temperature or feel |
|---|---|---|---|
| LED red light panel | Red and near-infrared light | No | Mild warmth on the skin, no sweating; Kivorla panel surface at or below 40°C |
| LED face mask | Red or blue light with near-infrared | No | Mild warmth at most |
| Incandescent heat lamp | Mostly heat, a little red light | Yes | Warm to hot; keep the lamp at least 18 inches away |
| Infrared sauna | Far infrared from heaters | Yes | Sweating; 43 to 57°C |
| Traditional sauna | Hot air | Yes | Sweating; 66 to 91°C |
| Tanning bed | UVA and UVB | No, built to tan | Tans and can burn the skin |
Mayo Clinic describes an infrared sauna as one that "uses light to make heat". Mayo Clinic, 2024 Cleveland Clinic puts infrared saunas at 43 to 57°C and traditional saunas at 66 to 91°C. Cleveland Clinic, 2026 ICNIRP notes that cabin heaters emit almost only far infrared, absorbed in the most superficial layers of the skin. ICNIRP Our red light sauna guide and heat lamp comparison go further.
Long, repeated contact with mild heat of 43 to 47°C, from laptops or heating pads, can cause erythema ab igne, a net-like red then brown rash. Riahi, 2012
Tanning beds give off UVA and UVB. The AAD reports that using them before age 20 can raise melanoma risk by 47%. AAD By contrast, research has not found that red light causes any type of cancer. AAD, 2024
Our shortest wavelengths are 460 nm on the mask and 480 nm on the panel, well clear of UV, so neither will tan you; see red light therapy and tanning.
Is redness or warmth after a session normal, and how long should it last?
A brief warm flush that fades within the hour is normal. Redness that lasts for hours, stinging or new dark patches mean the session was too much.
Next time, step back, dim or shorten the timer. ICNIRP advises stopping and seeking medical advice if reddening lasts more than a day. ICNIRP
If skin ever feels burned, stop the session and cool the area:
- Cool water: hold the skin under cool running water for 10 to 20 minutes. AAD Cleveland Clinic, 2025
- Skip home remedies: no ice, butter or toothpaste.
- See a doctor: for blisters, a burn larger than your palm, or pain that gets worse. Cleveland Clinic, 2025
Can a red light panel burn you if you sit too close?
Burns are a matter of dose and distance, and a heat burn normally needs skin at 45°C or more. Keep about 6 inches from the panel for a joint and 12 inches for a broad area, and never rest your skin on it.
Skin held at 44°C takes several hours before lasting damage, while a surface at 70°C causes it in under a second. ICNIRP Heat becomes painful at lower temperatures than those that injure skin, and that pain usually makes people move away within seconds. ICNIRP, 2013
The Kivorla panel's front surface stays at or below 40°C. Surface temperature is only part of the picture, though: absorbed light also warms the skin, which is why distance and session length matter.
- No contact: keep a gap between your skin and the panel at all times.
- Nothing over it: do not drape a towel or clothing over the panel.
- Too warm: step back, dim the channels or shorten the timer.
Is it safe to use red light therapy when sleepy, after a sauna or after sunburn?
Not when you might fall asleep, and not straight after a sauna or with recent sunburn. The warning from heat only protects you while you are awake and can feel it.
- Sleep: the panel manual says it is not for use by sleeping or unconscious people. Set the timer; if you forget, the panel stops at 5 minutes.
- Alcohol and medicines: ICNIRP notes that alcohol and some medicines can dull pain, and with it the urge to move away from heat. ICNIRP, 2013
- Medicines and light: our precautions rule out use with photosensitising medication, so anyone taking a medicine should check with their pharmacist or doctor before using either device.
- Reduced feeling: if you cannot feel heat normally in an area, ask your doctor first.
- After a sauna or hot shower: let your skin cool and dry first; never use the panel while overheated, sweaty or wet, and never inside a sauna cabin.
- Sunburn: the panel manual says not to use it if you have had sunburn on your body in the past 2 weeks. Never use either device on broken skin.
How do you keep a Kivorla panel or mask session comfortably warm?
Use the controls to stay in mild warmth: step back, dim the channels or shorten the timer. Both are light devices, not heaters, so a session should never need to feel hot.
The 9-Spectrum Red Light Therapy Panel carries 480, 590, 630, 660, 670, 810, 830, 850 and 1060 nm, each dimmable from 1 to 100%. It gives at least 1,567 W/m2 at 6 inches.
- Distance: about 6 inches for a joint, about 12 inches for a broad area such as the back or thighs.
- Time: 10 to 15 minutes per area, set on the controller from 1 to 30 minutes.
- Warmth: dim the 810, 830, 850 and 1060 nm channels first if you feel more than mild warmth.
- Eyes: wear the included goggles with your eyes closed. Near the face or neck, sit side-on or with your back to the panel, never facing it.
- Rest: leave at least 6 hours between 30-minute sessions.
The studies above used minutes of light. To stay close to that, use a shorter timer, turn the channels down from 100%, or step back to 12 inches.
For the mask, follow the manual's limits: 10-minute sessions up to 4 times a week at high brightness, or 15-minute sessions up to 3 times a week after building up with three 10-minute sessions the week before. Never use it for more than 20 minutes a day.
Read the precautions before ordering. Standard shipping to the US, UK and Germany is free. Under our return and refund policy, returns are accepted within 30 days: an unopened device with its seals intact is refunded less a 10% restocking fee, and an opened device that is undamaged and complete is refunded less 20%.
Kivorla devices are general wellness devices, not medical devices. If a session leaves a burn, blisters or redness that lasts more than a day, stop and speak to a doctor, and ask your doctor first if you have reduced feeling in your skin.