Last updated: September 4, 2026 | 11-minute read
Infrared therapy side effects became a more important safety question as high-irradiance home panels became more widely available. The safety advice should therefore address irradiance, exposure time, distance, wavelength, device temperature, and the manufacturer's instructions—not simply tell users not to stare at the light.
Infrared therapy side effects can include temporary skin redness, warmth, thermal discomfort, eye discomfort, and irritation in some users. The risk depends on the device, irradiance, exposure duration, distance, treated area, wavelength, and the user's health or medication history. Near-infrared wavelengths around 850 nm may travel farther through tissue than 660 nm red light under some conditions, but penetration is not a fixed depth and does not automatically mean deeper tissue heating.
What follows maps possible adverse responses to their proposed biological causes, explains how device parameters—irradiance, wavelength ratio, thermal management—may affect risk, and identifies users and body areas that may need extra caution. It is an educational framework for evaluating a device, not a treatment recommendation or a substitute for medical advice.
What the documented side effects actually are — and what causes them
Infrared therapy side effects mapped to biological causes diagram
The available clinical literature generally describes red and near-infrared photobiomodulation as well tolerated when appropriate device parameters are used. Temporary redness, warmth, irritation, or discomfort can occur, but their frequency depends on the device, application, and study population. There is not a single, well-established clinical ranking of side effects for every infrared therapy device.
What actually causes these side effects—is it the therapy itself, or something else?
Photobiomodulation research describes a biphasic dose-response pattern: more light is not always better, and the response can vary with irradiance, fluence, exposure time, wavelength, and tissue. This concept supports careful dose control, but it does not prove that every symptom after a session is caused by overexposure. [1]
Possible effects include:
- Transient erythema (skin reddening): may result from local vascular responses, warmth, or individual skin sensitivity. It should not be presented as the most common effect unless a specific study provides frequency data. Avci et al. (2013) discussed low-level light therapy in skin and reported reduction of UVB-induced erythema; that paper should not be cited as proof that erythema is a universal side effect or that it always resolves within 30–60 minutes. [2]
- Warmth and thermal discomfort: may occur when absorbed optical energy and heat generation exceed the user's comfort level. The result depends on irradiance, duration, distance, treated area, ambient conditions, contact with the skin, and device cooling.
- Eye discomfort or visual sensitivity: bright visible light can be uncomfortable, while near-infrared light may be invisible and therefore provide little visual warning. Eye risk must be assessed at the intended distance and geometry. IEC 62471 provides methods for evaluating photobiological hazards from lamps and LED sources; it does not automatically require protective eyewear for every red or infrared session. [3]
- Headache or nausea: these symptoms have been reported in some forms of bright-light therapy, but evidence specific to red and near-infrared therapy is limited. They should be described as possible symptoms rather than as proven results of dehydration, overheating, or "acclimation."
- Skin dryness, irritation, or tightness: may occur in some users, particularly when heat, prolonged exposure, or an existing skin condition is involved. These effects should not be described as universal or as a predictable result of photobiomodulation alone.
Is infrared therapy the same risk as UV exposure?
No. Red and near-infrared LED devices use non-ionizing optical radiation and do not have the same direct DNA-damaging mechanism as ultraviolet radiation. However, non-ionizing does not mean risk-free. Excessive optical exposure can cause heating or photobiological injury, and some products or procedures may involve photosensitizing substances. Risk must therefore be assessed by wavelength, output, exposure geometry, labeling, and the user's condition—not by the word "infrared" alone.
Understanding these distinctions is the first step toward reducing avoidable risk.
How device parameters determine side effect risk
Red light therapy panel annotated with irradiance wavelength lens angle and distance
Does the type of device change how likely side effects are?
Yes. Infrared therapy side effects can vary with irradiance, wavelength, exposure duration, distance, beam geometry, treated area, and thermal management. That is why "is infrared therapy safe?" cannot be answered with a single yes or no for every device.
Start with irradiance and distance. Irradiance is normally reported at a specified measurement plane and distance. For an ideal point source in the far field, irradiance can approximate an inverse-square relationship. Large LED panels, multiple emitters, lenses, reflections, and near-field measurements can behave differently. A panel measured above 200 mW/cm² at 6 inches should not automatically be assumed to deliver exactly one-quarter of that value at 12 inches. The manufacturer's measured data and instructions should be used instead.
Wavelength can affect tissue absorption and optical transport. 660 nm red light is often used for more superficial applications, while 850 nm near-infrared light may travel farther through some tissues. Neither wavelength has a universally fixed penetration depth, and neither wavelength alone determines whether a session will cause surface or deep heating. Tissue composition, irradiance, exposure time, beam geometry, and cooling also matter.
Lens angle affects beam distribution. A narrow lens may concentrate light into a smaller area, but the actual irradiance at the target plane depends on LED output, optics, distance, beam profile, and panel design—not on lens angle or electrical wattage alone. The correct comparison is measured irradiance at the same target distance and area.
Thermal management remains relevant because excessive component or housing temperature can affect user comfort, output stability, and product reliability. These risks should be evaluated with temperature testing and irradiance measurements over the intended session—not inferred only from the presence of cooling fans.
Side effects vary by device type and irradiance level
Low-irradiance nasal lamp vs high-irradiance full-body panel risk comparison
A small red light device and a full-body panel do not necessarily have the same exposure profile. Total energy depends on irradiance, time, treated area, and distance. Device categories such as "low," "mid," and "high" irradiance are practical descriptions, not universal regulatory or clinical risk classes.
Low-irradiance, localized devices (~10–30 mW/cm²)
At this output range, surface heating may be lower than with a high-irradiance panel, but safety still depends on exposure duration, distance, treated tissue, beam geometry, and product labeling. A nasal or mucosal device requires particular attention to local tissue tolerance and accidental eye exposure. It is not appropriate to label the eye risk as low without device-specific testing and instructions.
Mid-range targeted devices (~100–150 mW/cm²)
Thermal discomfort may become more likely when exposure time is extended or the device is held closer than specified. Eye safety should be assessed especially when near-infrared output is directed toward the face or eyes. A value such as 124 mW/cm² is not, by itself, proof that a session falls within an established dosing window. For example, 124 mW/cm² for 5 minutes equals approximately 37.2 J/cm² before other optical or geometric factors are considered. Dosing should be based on the intended use, device instructions, and supporting evidence—not on a single irradiance number.
High-irradiance full-body panels (>200 mW/cm²)
This output level calls for careful control of distance, duration, temperature, and eye exposure. A high irradiance value is not itself a regulatory classification. Users with photosensitivity disorders, relevant medication exposure, or a medical condition that may be affected by light or heat should seek professional advice and follow the device labeling.
The regulatory status must also be precisely described. For example, the record for Australian ARTG number 515205 indicates that Kingsmead Pty Ltd is the sponsor, reddotled is the manufacturer, and the product falls under the Class IIa registration category. Health Canada license number 113779 is active and specifies the device identifiers, including RDPRO1000, RDPRO1500, RDPRO300, and RDPRO750. [4][5]
Regulatory classifications indicate the requirements applicable in a particular jurisdiction and product use. They do not, by themselves, prove clinical effectiveness, guarantee the absence of side effects, or establish that a product is safer than every Class I device.
Who faces elevated risk—and where on the body to be cautious
Not everyone has the same risk profile from infrared therapy. The relevant precautions depend on the user's condition, medication, the device's intended use, and the treated area.
People taking photosensitizing medications should check the specific medicine's official labeling or consult a prescribing clinician. Drug-induced photosensitivity is usually associated with ultraviolet or visible wavelengths, and sensitivity cannot automatically be assumed for 850 nm near-infrared light. Examples of medicines sometimes associated with photosensitivity include certain tetracyclines, antifungals, NSAIDs, and St. John's Wort, but the risk is drug-specific and should not be generalized to all red or near-infrared devices. [6]
People with known photosensitivity disorders, active skin disease, or an unexplained reaction to light should obtain professional advice before use. Lupus and porphyria can involve abnormal light responses, but the relevant wavelengths and clinical risk vary; a blanket statement that all red or near-infrared exposure is unsafe is not justified.
For active cancer or a history of cancer at the treatment site, users should follow the device labeling and consult their oncology or medical team. Direct exposure over a known tumor should not be presented as an established universal contraindication based only on precautionary practice; the oncologic safety evidence is still indication- and context-dependent. [7]
Pregnancy is another area where product labeling and medical advice matter. Many devices or clinical services recommend avoiding use because safety data are limited, but this is a precaution rather than proof of documented fetal harm. The article should not claim that every red or infrared device is universally prohibited during pregnancy.
For pacemakers, insulin pumps, or other implanted electronic devices, users should follow the implant manufacturer's advice and the light-device instructions. A general statement that every high-irradiance panel must not be used over the chest or upper back requires device-specific evidence and should not be presented as a universal rule.
The eyes deserve particular attention. The absence of visible discomfort does not establish retinal safety, especially with invisible near-infrared output. However, IEC 62471 is a lamp and lamp-system assessment standard, not a universal eyewear certification. Eye protection should be used when the device labeling, risk assessment, intended treatment area, or professional instructions call for it. Users should not stare directly into high-intensity LEDs.
Direct exposure over the thyroid, open wounds, active infections, or lesions should be handled according to product labeling and professional advice. These are precautionary areas; they should not be described as universal exclusion zones without a cited device-specific or clinical basis.
A user who feels worse after a session should stop, allow symptoms to settle, and review the device instructions, distance, duration, heat, hydration, and other possible causes. "Detoxification" is not an established explanation for these symptoms. Persistent, severe, or recurring symptoms warrant medical evaluation. Evidence that evening red or near-infrared sessions generally disrupt sleep is limited and may depend on wavelength, brightness, timing, and individual response.
Knowing the relevant risk factors is the clinical side of safe use. The engineering side is whether the device has reliable output, thermal controls, electrical safety testing, and clear instructions.
What separates a certified device from an uncertified one—and why it matters for safety
A device manufacturer's ISO 13485:2016, MDSAP, and ETL documents can provide useful evidence about its quality-management and electrical-safety processes, but their meaning depends on the named legal entity, certificate scope, covered models, issuing organization, and validity period.
The practical question is whether documented controls can reduce device-related uncertainty. They can help, but no certificate makes a session error-proof or proves clinical effectiveness.
IEC 62471:2006 provides exposure limits, measurement methods, and a risk-group classification framework for photobiological hazards from lamps and LED sources across 200–3000 nm. A report should identify the tested configuration, measurement geometry, wavelength range, and result. IEC 62471 testing does not replace product-specific operating instructions or prove that every use condition is safe. [3]
ISO 13485:2016 is a quality-management-system standard for organizations involved in medical devices. It does not, by itself, certify every finished product, verify every wavelength or irradiance claim, or prove clinical efficacy. Its value depends on the certificate scope, site, activities, audit status, and the manufacturer's implementation of design, production, complaint, and corrective-action controls.
MDSAP uses a single audit approach to assess applicable quality-management and regulatory requirements for participating jurisdictions. It is not automatic market authorization in every country and does not validate every product claim. ETL listing can provide independent electrical-safety evidence for the listed product configuration, but it does not establish photobiological safety or therapeutic effectiveness unless those matters are separately tested.
FDA establishment registration and device listing should also be described accurately. FDA states that registration or listing does not denote FDA approval, clearance, or authorization of the establishment or its products. Product-specific market authorization or exemption status must be checked separately. [8]
Documented certifications, traceable irradiance data, thermal testing, and controlled engineering changes can reduce uncertainty. They do not prove that every user will avoid side effects. A user who sits too close, exceeds the stated session time, ignores eye-safety instructions, or uses a device despite a relevant contraindication may still experience discomfort or injury.
Key takeaways
Infrared therapy side effects can include temporary redness, warmth, irritation, eye discomfort, and other individual reactions. Risk depends on the device and the user—not on wavelength alone. The most useful safeguards are to follow the manufacturer's distance and duration instructions, use measured irradiance data at the stated target plane, control heat, avoid direct eye exposure, and seek professional advice when a medication, medical condition, pregnancy, cancer history, implanted device, or persistent symptom is relevant.
FAQ
Why do I feel worse after red light therapy?
A temporary headache, fatigue, warmth, or general discomfort can have many possible causes, including excessive exposure, heat, bright visible light, dehydration, an underlying condition, or unrelated timing. "Detoxification" or a guaranteed cellular adjustment is not an established explanation. Stop the session, review the device instructions, and use a shorter or less intense exposure only if the product guidance permits it. If symptoms are severe, persistent, or recurrent, seek medical advice.
Who cannot use red light therapy?
There is no single universal list for every red light therapy or infrared therapy device. People with photosensitivity disorders, relevant medication exposure, active infection or lesions at the treatment area, pregnancy, cancer at or near the treatment area, implanted electronic devices, or light-triggered epilepsy should check the product labeling and consult a qualified clinician before use. FDA materials for certain photobiomodulation procedures list several of these precautions, but the information is device- and use-specific rather than a universal rule for every product. [9]
Are there negative effects to red light therapy?
Yes. Possible effects include temporary redness, warmth, irritation, eye discomfort, headache, or other individual reactions. Serious injury is uncommon when a suitable device is used as directed, but risk can increase with excessive exposure, high temperature, direct eye exposure, incorrect distance, or relevant medical conditions. IEC 62471 can support photobiological hazard evaluation, but it does not replace the product's instructions or prove that a device is suitable for every user.
Where should you not put red light therapy?
Do not direct a high-intensity red or near-infrared source into the eyes unless the device is specifically designed and labeled for ocular use. Avoid areas listed in the product instructions, including areas with active infection, an open wound, an untreated lesion, or a known photosensitive reaction. During pregnancy, over the abdomen or lower back should be treated according to product labeling and medical advice. For cancer, thyroid conditions, or implanted electronic devices, consult the relevant clinician and follow both the light-device and implant instructions. These precautions depend on the device and user; they should not be presented as identical for every product.
References
- [1] Hamblin, M. R. "Mechanisms and Mitochondrial Redox Signaling in Photobiomodulation." Photochemistry and Photobiology, 2018, 94(2), 199–212. https://doi.org/10.1111/php.12864
- [2] Avci, P. et al. "Low-level laser (light) therapy (LLLT) in skin: stimulating, healing, restoring." Seminars in Cutaneous Medicine and Surgery, 2013. https://pmc.ncbi.nlm.nih.gov/articles/PMC4126803/
- [3] International Electrotechnical Commission. "IEC 62471:2006—Photobiological safety of lamps and lamp systems." https://webstore.iec.ch/en/publication/7076
- [4] Australian Therapeutic Goods Administration. "Kingsmead Pty Ltd—Red/infrared light phototherapy unit, ARTG 515205." https://www.tga.gov.au/resources/artg/515205
- [5] Health Canada. "Active licence listing by company—Licence No. 113779." https://health-products.canada.ca/mdall-limh/information?companyId=191570&lang=eng
- [6] DermNet NZ. "Drug-induced photosensitivity." https://dermnetnz.org/topics/drug-induced-photosensitivity
- [7] Glass, G. E. et al. "A Systematic Review of the Oncologic Safety of Low-Level Light Therapy." Lasers in Medical Science, 2023. https://pubmed.ncbi.nlm.nih.gov/36722207/
- [8] U.S. Food and Drug Administration. "Are There ‘FDA Registered' or ‘FDA Certified' Medical Devices?" https://www.fda.gov/medical-devices/consumers-medical-devices/are-there-fda-registered-or-fda-certified-medical-devices-how-do-i-know-what-fda-approved
- [9] U.S. Food and Drug Administration. "Non-Invasive Body Contouring Technologies—Photobiomodulation." https://www.fda.gov/medical-devices/aesthetic-cosmetic-devices/non-invasive-body-contouring-technologies