What safety risks are associated with red light therapy?

While red light therapy is overwhelmingly safe, understanding the hierarchy of risks helps in mitigation.
Most Common (Minor):
Eye Strain/Discomfort: From not wearing goggles or looking at bright red LEDs. Usually temporary.
Mild Skin Redness/Dryness: Due to slightly excessive duration or heat. Resolves quickly.
Headache: From long sessions or dehydration.
Moderate Risks:
Thermal Burns: Rare, but possible with malfunctioning devices, lack of cooling, or extreme proximity for long durations.
Photo-reactions: In users on photosensitizing meds or with specific autoimmune conditions (lupus), leading to rashes or flares.
Ineffectiveness/Wasted Money: Using the wrong dose (too high or too low) leads to no results, which is a practical risk.
Severe Risks (Rare/Theoretical):
Retinal Damage: Staring directly into high-power NIR sources without protection can cause permanent eye injury. This is the most significant severe risk.
Stimulation of Malignancy: Theoretical risk of accelerating growth in untreated skin cancers or pre-cancers if treated directly.
Seizures: Only in individuals with photosensitive epilepsy if the device flickers at specific frequencies (rare in modern DC-powered LEDs).
Overall, the risk profile is extremely favorable compared to pharmaceuticals or invasive procedures. Most risks are easily avoided with eye protection, adherence to time limits, and purchasing certified equipment.