According to a wealth of current scientific research and clinical evidence, conventional red light therapy (typically with a wavelength of 600-700nm) and near-infrared light therapy (typically with a wavelength of 800-880nm), used for beauty, health, and treatment, do not inherently cause cancer. In fact, some studies suggest they may even have anti-cancer potential and are often used to help alleviate the side effects of cancer treatment.
Below, I will explain the principles and current research status in detail.
1. How Red Light Therapy Works (Why It’s Generally Non-Carcinogenic)
Red light therapy uses visible and near-infrared light, which is fundamentally different from ultraviolet (UV) light, which is known to cause cancer.
Energy Difference: Red and near-infrared light photons have lower energy and are considered non-ionizing radiation. This means they lack the energy to damage cellular DNA or directly cause genetic mutations, which is one of the root causes of cancer.
Mechanism of Action: Red light therapy primarily targets cytochrome c oxidase in the mitochondria. Absorbing light energy can optimize the function of the cellular respiratory chain, thereby:
Increasing adenosine triphosphate (ATP) production: This provides cells with more energy.
Regulating reactive oxygen species (ROS) levels: Within moderate ranges, ROS can act as signaling molecules, activating antioxidant pathways, enhancing cellular antioxidant capacity, and reducing oxidative stress (a key factor in aging and disease).
Triggering signaling pathways: This promotes cell repair, reduces inflammation, and improves blood circulation.
Precisely because of its low energy content and its mechanism of action, which regulates rather than destroys cellular function, standard doses of red light therapy are not considered carcinogenic.
2. Research evidence supports its safety and even benefits.
Lack of evidence of carcinogenicity: To date, no authoritative studies or clinical reports worldwide have demonstrated that properly used, qualified, red light/NIR phototherapy devices can cause or promote cancer.
Used to alleviate side effects of cancer treatment: Red light therapy (particularly low-level laser therapy (LLLT)) is widely used by oncologists to manage the side effects of cancer treatment, such as:
Preventing and treating oral mucositis (common mouth ulcers and pain after radiotherapy or chemotherapy). Relieve lymphedema (common after breast cancer surgery).
Aid wound healing and reduce scarring.
These applications are based on its proven safety.
Potential anti-cancer research (still under development):
Some laboratory studies have found that under specific conditions (such as very high power density and dose), photodynamic therapy (PDT)—a treatment that requires photosensitizing drugs—can use specific wavelengths of light to target and destroy cancer cells. However, this concept is completely different from standard, drug-free red light therapy.
It is theorized that red light therapy may indirectly create a microenvironment that is unfavorable for cancer cell development by enhancing the function and antioxidant defenses of healthy cells. However, this is still in the early stages of research and cannot be used as a treatment.
3. Exceptions and Precautions to Note
Although generally safe, caution is warranted in certain extreme or special circumstances:
Preexisting skin cancer or precancerous lesions: Patients with confirmed skin cancer (such as melanoma or basal cell carcinoma) or precancerous lesions such as actinic keratosis are advised to avoid using red light devices directly on the affected area. While red light itself is not carcinogenic, any thermal or optical stimulation of the tumor area could theoretically have unpredictable effects (although the risk is extremely low). Always consult your oncologist.
Overuse and high-intensity exposure: Excessive exposure to anything can be harmful. Extreme, ultra-high doses of light can stress cells by producing excessive reactive oxygen species (ROS), but this is unlikely to be achieved in routine home or clinical use.
Device quality: Using low-quality, uncertified devices can be risky, such as unintended inclusion of UV components or unstable power. Choose a reputable brand with regulatory approvals (such as FDA clearance).
Summary
Conventional red/near-infrared light therapy does not cause cancer. Its mechanism of action is completely different from UV light, and its energy level is insufficient to damage DNA.
Extensive evidence supports its safety, and it is widely used to help cancer patients manage treatment side effects.
For patients with existing skin cancer or precancerous lesions, out of an abundance of caution, avoid using it on lesions and consult a doctor beforehand.
Always choose high-quality, certified devices, follow the instructions, and avoid overuse.
Post time: 09-22-25