Infrared light therapy is generally safe when used correctly. The light operates at energy levels that don’t break apart molecules or generate significant heat in tissue, which puts it in a fundamentally different risk category than ultraviolet light or ionizing radiation. That said, “safe” comes with important caveats around session length, device power, eye protection, medications, and certain health conditions.
How Infrared Light Interacts With Your Body
Infrared light therapy works by sending photons into your tissue, where they’re absorbed by an enzyme in your mitochondria called cytochrome c oxidase. This enzyme plays a central role in cellular energy production, and absorbing infrared light appears to boost its activity. The result is increased energy output at the cellular level, which can reduce inflammation and promote tissue repair.
How deep the light actually reaches depends on the device’s power and wavelength. Low-powered LEDs (under 1 watt) often can’t push light through even 2 mm of skin. Higher-powered lasers in the 810 nm range can penetrate that same depth, though they lose 83% or more of their energy doing so. Pulsed light penetrates significantly better than continuous light: in one study, a pulsed 810 nm laser delivered 69% of its energy through 1.9 mm of skin, compared to just 17% for the same laser in continuous mode. At deeper distances of 2.5 to 3 cm, only about 0.5% to 3% of the original energy gets through. This means the therapy primarily affects skin, superficial muscles, and joints rather than deep organs.
Known Side Effects
The most common side effect is mild, temporary redness at the treatment site, similar to light sunburn. This typically fades within hours and isn’t considered harmful.
The more serious skin risk comes from repeated, prolonged heat exposure. A condition called erythema ab igne produces a distinctive mottled, net-like discoloration on the skin. It was historically associated with sitting too close to a fire, but it shows up in people who chronically apply heat sources to the same area of skin. If the exposure continues over months or years, the affected skin can develop precancerous changes, and in rare cases, squamous cell carcinoma or other skin cancers have been reported at the site. This is primarily a concern with heat-generating infrared sources used excessively over long periods, not with properly timed therapy sessions.
Eye Safety
Your eyes are the most vulnerable part of your body during infrared therapy. The retina absorbs infrared light, and the primary danger is thermal: the light heats the melanin in the retinal pigment layer and surrounding tissue. International safety standards (ISO 60825 and ISO 15004) set strict limits on how much infrared energy the eye can safely receive, with maximum permissible exposure for near-infrared wavelengths around 880 nm set at 4.6 milliwatts per square millimeter for long-duration exposure.
In practical terms, you should always wear the protective goggles that come with your device, or purchase appropriate ones rated for the wavelength you’re using. Never look directly into an infrared light source, even if it appears dim or invisible to the naked eye. Near-infrared wavelengths above 780 nm are largely invisible, so you won’t instinctively blink or look away the way you would with a bright visible light.
Who Should Be Cautious
If you have or have had cancer, the standard recommendation is to avoid infrared therapy over areas bearing tumors. Practitioners have historically withheld the therapy from cancer patients out of concern that stimulating cellular activity could promote tumor growth or metastasis. While some preliminary research has explored whether this fear is warranted, current guidelines still advise caution, particularly over any area where there is active cancer or risk of recurrence.
Pregnancy is another area where infrared therapy lacks sufficient safety data, so most practitioners recommend avoiding it.
People with darker skin tones may be more sensitive to visible-spectrum red light therapy, which can trigger dark spots. Starting with lower doses and shorter sessions is a reasonable approach. For wavelengths deeper into the infrared range (above 780 nm, which is invisible), this concern is less established, but caution with initial exposure still makes sense.
Photosensitizing Medications
Several hundred medications increase your skin’s sensitivity to light. While the strongest photosensitivity reactions tend to involve ultraviolet wavelengths, the broad category of light-sensitizing drugs is worth knowing about if you’re using any form of light therapy. Common classes include diuretics like hydrochlorothiazide, blood pressure medications like ACE inhibitors and calcium channel blockers, the acne drug isotretinoin (and other retinoids), certain antibiotics, NSAIDs, hormonal contraceptives, and the heartburn medication ranitidine. If you take any of these and notice unusual redness, burning, or skin changes after infrared sessions, the medication could be a contributing factor.
How to Use It Safely
Three variables determine your dose: the power output of the device, your distance from it, and the time you spend in front of it.
- Session length: Clinical trials typically use 5 to 20 minutes per treatment area. Starting at 5 to 10 minutes and increasing gradually is the standard approach.
- Distance: Most devices work best at 6 to 24 inches from the skin. Your device should specify the optimal distance for its power output. A small panel rated at 100 milliwatts per square centimeter at 6 inches will deliver far less energy at 36 inches.
- Frequency: Three to five sessions per week is typical. You can assess how your body responds before moving to daily use.
More is not better. The biological response to light therapy follows a biphasic pattern, meaning too little does nothing and too much can actually inhibit the benefits or cause irritation. Sticking within recommended parameters matters more with infrared therapy than with many other wellness tools.
What “FDA Cleared” Actually Means
Many infrared therapy devices are marketed as “FDA cleared,” which sounds reassuring but means something specific and limited. The FDA classifies photobiomodulation devices as Class II medical devices. To reach the market, they go through a 510(k) clearance process, which means the manufacturer demonstrated the device is substantially similar to one already legally sold. This is not the same as FDA approval, which involves rigorous clinical trials proving a device works for a specific condition. FDA clearance confirms a device meets basic safety and manufacturing standards. It does not confirm it will deliver the health benefits claimed in marketing materials.
Home devices vary enormously in power, wavelength accuracy, and build quality. Cheaper devices may emit wavelengths that differ from what’s listed on the label, or they may lack sufficient power to deliver a therapeutic dose at any practical distance. Checking for 510(k) clearance is a reasonable minimum when choosing a device, but it’s no guarantee of effectiveness.