Red Light Therapy Dangers: 3 Harms on Record, 1 Fear Without Evidence

Quick Answer: Red light therapy is low-risk for most people, but it is not risk-free, and the documented harms cluster in three places. First, the eyes: laboratory tests found that some red laser devices sold for children’s myopia reach eye-safety limits in 1.4 to 2.8 seconds, and a case of retinal damage after repeated use was published in 2023. Second, the skin: FDA’s adverse-event database holds 107 reports for over-the-counter light-based wrinkle devices, most of them irritation, discoloration and redness, with 10 coded as burns. Third, light-activated drugs: some prescription medicines are designed to react to red light, and their labels tell patients to avoid bright light for days. The fourth worry, that red light therapy causes cancer, is not supported: two systematic reviews found no clinical data linking it to new or recurrent tumours. An advertisement for a red light panel appears near the end of this page.

Searches for “red light therapy dangers” and “is red light therapy safe” usually land on pages that either wave the question away or list a dozen theoretical risks. This page sticks to what is on record: published case reports, laboratory measurements of real devices, FDA adverse-event reports and drug labels. If you want to know what red light therapy is good for, read our red light therapy benefits page; if you are choosing a device, see red light therapy at home and our page on red light therapy masks.

Danger 1: your eyes, and the devices that shine light into them

The clearest documented eye harm comes from one specific kind of device: low-level red laser instruments that children look into for a few minutes a day to slow myopia. These are not face masks or wall panels. They deliver a beam straight into the eye, which is exactly why they were measured.

In 2024, researchers at the University of Houston tested two such instruments against the US laser-safety standard. For one device, the time to the maximum permissible exposure for photochemical damage was 0.55 to 7.0 seconds, depending on pupil size. Their conclusion: “3 min of continuous viewing approached or surpassed the MPE, putting the retina at risk of photochemical and thermal damage.”

A 2026 follow-up by the same group tested four devices. Two laser-based instruments reached the group 1 safety limit in 2.8 and 1.4 seconds for a 7 mm pupil. An LED-based instrument, by contrast, took 22,761 seconds, more than six hours, to reach the same limit. The authors wrote that laser-based devices “reach ANSI safety limits within exposure times below the recommended 180-second treatment time”.

That difference between a focused laser and diffuse LED light is the most important point on this page for anyone using a home panel. The measured risk sits with lasers aimed into the eye.

The case report

In 2023, JAMA Ophthalmology published a case report of retinal damage in a 12-year-old girl with myopia after repeated low-level red-light laser exposure. A 2024 systematic review of 20 studies covering 1,436 children who received this treatment found that the published case reports described one patient, with a reversible drop in vision that “completely resolved 4 months after treatment cessation”, and “no cases of permanent vision loss”. The most common symptom was a temporary afterimage that faded within 6 minutes.

Two caveats belong next to that reassuring review. One of its authors is listed as an inventor on related patents and as a director and shareholder of a company that sells such devices. And its own conclusion calls for eye imaging before and during therapy plus home vision checks, which is not what reassurance usually looks like.

Eyes open or closed?

We found no trial that tested eyes-open against eyes-closed use of a home panel. What we did find is how a prescription red-light lamp is handled in medicine. The FDA-approved label for Ameluz, a skin-cancer-precursor treatment that uses a red LED lamp at about 635 nm, says: “Patients and healthcare providers must wear protective eyewear before operating” the lamp, and “Avoid staring directly into the light source.” If the clinic version of a red lamp comes with mandatory eye protection, the conservative reading for a home panel is to keep your eyes closed or covered and never stare into it.

For more on how red light reaches the eye and what the myopia devices actually measure, our home red light therapy page covers the panel side, and our blue light glasses page covers the other end of the spectrum.

Danger 2: skin reactions and burns in FDA’s adverse-event reports

The FDA keeps a database of medical device reports, called MAUDE, where manufacturers, hospitals and the public report injuries and malfunctions. We counted the reports for the light-therapy product codes on 21 October 2026 using the FDA’s openFDA interface.

A single report can list several problems, so the problem counts overlap and do not add up to the report total. The OHS and OLP reports together span August 2005 to August 2026.

Three things stand out. For LED wrinkle devices, the typical report is irritation, redness or discoloration rather than a burn. Burns dominate the heat-lamp category, with 122 burn codes across its 294 reports against 10 across 107 for wrinkle devices; heat lamps are a different technology that works by warming tissue. And eye complaints appear in both the wrinkle and acne categories, which is consistent with the eye advice above.

What these numbers cannot tell you

The FDA is explicit about the limits of this database: report data “is not intended to be used either to evaluate rates of adverse events, evaluate a change in event rates over time, or to compare adverse event occurrence rates across devices,” and “Establishing a causal relationship is especially difficult if circumstances surrounding the event have not been verified or if the device in question has not been directly evaluated.” A report means someone linked a problem to a device, not that the device caused it, and there is no count of how many people used each device without trouble.

One acne-mask report in the database is coded as a death. Its narrative describes a consumer who had an ectopic pregnancy while using the mask; nothing in the report establishes that the mask played any role. It is a good illustration of why these reports are a signal to look at, not proof.

Danger 3: medicines that are switched on by red light

Most “photosensitivity” warnings you see online are about sunlight and ultraviolet light. The specific concern for red light therapy is a smaller group of drugs that are deliberately activated by red light as part of a treatment called photodynamic therapy.

• Verteporfin (Visudyne), used for an eye condition, works as “a two-stage process requiring administration of both verteporfin for injection and nonthermal red light.” Its label says that after the injection, “care should be taken to avoid exposure of skin or eyes to direct sunlight or bright indoor light for 5 days.”
• Aminolevulinic acid gel (Ameluz), used with a red LED lamp at around 635 nm for actinic keratoses, carries the warning: “Protect treated lesions from sunlight exposure for 48 hours post treatment.”

If you have had either of these treatments, or any photodynamic therapy, a home red light session in the days afterwards is exactly the kind of bright light exposure those labels warn against. Ask the doctor who treated you when it is safe to resume.

We did not find a verified source showing that common photosensitizing medicines, such as some antibiotics or diuretics, react to the red and near-infrared wavelengths used by home panels. Many device manuals still advise checking with a doctor if you take light-sensitising medicines, and that is a sensible precaution rather than a documented danger.

The fear without evidence: does red light therapy cause cancer?

This is one of the most searched worries, and the honest answer is that no clinical evidence supports it so far.

A 2019 systematic review looked at the safety of photobiomodulation used to prevent and manage cancer-treatment side effects, such as mouth sores and lymphoedema, in people who have or had cancer. It included 27 articles and concluded that this use “does not lead to the development of tumor safety issues.” A 2023 systematic review focused on cosmetic skin rejuvenation found “no relevant clinical trial data linking PBM with any significant adverse events, including the finding of a new or recurrent malignancy,” and saw “no evidence to support the proposition that it should be avoided by patients who have previously undergone treatment for cancer.”

The same 2023 review is careful about what it does not know. In animal tumour models, results “varied” with “no clear pattern emerging”, and its effects on how invasive cancer cells are in the lab were “equivocal”. A 2022 review of 75 studies covering 2,712 people treated with low-level laser therapy during cancer care found “minor and infrequent adverse reactions”, while noting that most of those studies had weaknesses.

So the defensible statement is: there is no clinical evidence that red light therapy causes cancer, and the evidence base is mostly built on supervised medical use rather than years of daily home panel use. If you have an active cancer or a suspicious skin lesion, the place for a light device is a conversation with your oncologist or dermatologist, not a mirror at home.

What we could not find evidence for

We searched for, and did not find verified sources on, three other commonly listed risks: harm in pregnancy, effects on the thyroid from neck devices, and harm from daily long-term home use over years. Absence of evidence here means these questions have not been studied well, not that the answer is known to be “safe”. Pregnant people and anyone with a thyroid condition should ask their doctor before using a light device on the abdomen or neck.

Who should be most careful

• Children using laser-based myopia devices, where the documented eye risk is concentrated; these should be supervised by an eye doctor with retinal imaging, as the 2024 review itself recommends.
• Anyone who has recently had photodynamic therapy with a light-activated drug such as verteporfin or aminolevulinic acid.
• People with eye disease, or anyone tempted to stare into a panel: keep your eyes closed or protected.
• People using heat lamps or high-power infrared devices, where burns dominate the FDA reports.
• People with cancer, a suspicious skin lesion, pregnancy or thyroid disease, where the evidence is thin and a doctor should decide.

Frequently Asked Questions

Is red light therapy safe?

For most adults using an LED device as directed, the documented risks are mostly skin irritation and eye discomfort. The serious harms on record involve red laser devices aimed into children’s eyes for myopia, heat lamps that cause burns, and light-activated prescription drugs. FDA adverse-event reports cannot show how common any of these problems are.

Is red light therapy bad for your eyes?

Laser-based red light devices used for myopia have been measured reaching eye-safety limits in 1.4 to 2.8 seconds, and a case of retinal damage after repeated use has been published. An LED-based device in the same tests took over six hours to reach the limit. With any panel or mask, avoid looking into the light and protect your eyes.

Should my eyes be open or closed during red light therapy?

No trial has compared the two for home panels. A red LED lamp used in medicine carries a label requirement for protective eyewear and a warning not to stare into the light, so the cautious choice is eyes closed or covered.

Can red light therapy cause cancer?

No clinical evidence shows that it does. Systematic reviews from 2019 and 2023 found no clinical data linking photobiomodulation with new or recurrent tumours, though animal studies gave mixed results and long-term daily home use has not been studied.

Can red light therapy burn you?

Yes, burns appear in FDA’s adverse-event reports, especially for infrared heating lamps (122 burn codes across 294 reports) and less often for LED wrinkle devices (10 burns across 107 reports). Follow the device’s distance and time limits and stop if the skin becomes painful or blistered.

Which medicines don’t mix with red light therapy?

Light-activated photodynamic therapy drugs such as verteporfin and aminolevulinic acid are designed to react to red light; their labels warn against bright light for 5 days and 48 hours respectively. For other light-sensitising medicines, ask your doctor or pharmacist.

The Bottom Line

The documented dangers of red light therapy are specific rather than general. They concentrate on lasers aimed into the eye, heat-producing lamps that burn, and drugs designed to react to red light. LED wrinkle devices mostly generate reports of irritation and redness, and the cancer fear has no clinical evidence behind it so far. Protect your eyes, respect the time and distance limits, check with a doctor if you are on a light-activated drug or have cancer, pregnancy or a thyroid condition, and treat any device’s “FDA” claims as something to verify rather than assume.

Sources

1. Ostrin LA, Schill AW. Red light instruments for myopia exceed safety limits. Ophthalmic Physiol Opt, 2024. PMID 38180093. MPE for photochemical damage 0.55-7.0 s for 2-7 mm pupils; “3 min of continuous viewing approached or surpassed the MPE”. Checked 21 October 2026.
2. Ostrin LA, Schill AW. Safety Evaluation of 4 Red Light Therapy Devices for Myopia. JAMA Ophthalmol, 2026. PMID 41642586. Group 1 limits reached in 2.8 and 1.4 seconds for two laser devices; LED-based AirDoc 22,761 seconds; recommended treatment time 180 seconds. Checked 21 October 2026.
3. Liu H, et al. Retinal Damage After Repeated Low-level Red-Light Laser Exposure. JAMA Ophthalmol, 2023. PMID 37227712. Case report, 12-year-old patient with myopia. Checked 21 October 2026.
4. Chen Y, et al. Safety of repeated low-level red-light therapy for myopia: A systematic review. Asia Pac J Ophthalmol, 2024. PMID 39672511. 20 studies, 1,436 children treated; one patient’s reversible decline “completely resolved 4 months after treatment cessation”; “No cases of permanent vision loss”; afterimage resolving within 6 minutes; author conflict of interest disclosed (patents; director and shareholder of Eyerising). Checked 21 October 2026.
5. US Food and Drug Administration. openFDA device adverse event (MAUDE) API, counts by product code OHS, OLP, OAP and ILY, event type and patient problem. open.fda.gov. Queried 21 October 2026. OHS 107 reports (96 injury); OLP 51 (44 injury); OAP 38 (15 injury); ILY 294 (200 injury); OHS and OLP reports dated August 2005 to August 2026.
6. US Food and Drug Administration. Manufacturer and User Facility Device Experience Database (MAUDE), “Limitations of Medical Device Reports”. fda.gov. Checked 21 October 2026.
7. US Food and Drug Administration. Product classification database: OHS “Light Based Over The Counter Wrinkle Reduction”, OLP “Over-The-Counter Powered Light Based Laser For Acne”, OAP “Laser, Comb, Hair”, ILY “Lamp, Infrared, Therapeutic Heating”. open.fda.gov. Checked 21 October 2026.
8. VISUDYNE (verteporfin for injection) prescribing information, DailyMed set ID 952f4c80-50b1-4308-9ee6-311ffefb13df. “Avoid exposure of skin or eyes to direct sunlight or bright indoor light for 5 days”; “a two-stage process requiring administration of both verteporfin for injection and nonthermal red light”. dailymed.nlm.nih.gov. Checked 21 October 2026.
9. AMELUZ (aminolevulinic acid hydrochloride) gel prescribing information, DailyMed set ID 650daa9f-aeec-49ce-95b9-5fa20b988afd. Red light lamps “with a narrow spectrum around 635 nm”; “Patients and healthcare providers must wear protective eyewear”; “Avoid staring directly into the light source”; “Protect treated lesions from sunlight exposure for 48 hours post treatment”. dailymed.nlm.nih.gov. Checked 21 October 2026.
10. de Pauli Paglioni M, et al. Tumor safety and side effects of photobiomodulation therapy used for prevention and management of cancer treatment toxicities. A systematic review. Oral Oncol, 2019. PMID 31109692. 27 articles; “does not lead to the development of tumor safety issues”. Checked 21 October 2026.
11. Glass GE. Photobiomodulation: A Systematic Review of the Oncologic Safety of Low-Level Light Therapy for Aesthetic Skin Rejuvenation. Aesthet Surg J, 2023. PMID 36722207. “No relevant clinical trial data linking PBM with any significant adverse events, including the finding of a new or recurrent malignancy”; in vivo tumour models “varied results with no clear pattern”; invasiveness “equivocal”. Checked 21 October 2026.
12. Redman MG, Harris K, Phillips BS. Low-level laser therapy for oral mucositis in children with cancer. Arch Dis Child, 2022. PMID 34230010. 75 studies, 2,712 patients, “minor and infrequent adverse reactions”; most studies had quality weaknesses. Checked 21 October 2026.
13. FliKEZE SpectraPanel Pro 78 product page: wavelengths 630, 660, 810 and 850 nm; “Verified by FDA”. flikeze.com. openFDA 510(k) searches for “FliKEZE” and “SpectraPanel”: 0 records. Checked 21 October 2026.