Does Red Light Therapy Cause Side Effects?Last Updated:
Light therapy is rapidly becoming a popular alternative to traditional treatments for a broad range of conditions and general wellness concerns. Various light wavelengths serve different purposes and exhibit disparate safety levels and side effects.
Our bodies’ biological processes are closely tied to light exposure.
Red light-emitting diode (LED) and near-infrared (NIR) light are among the safest of wavelengths utilized in light therapy today.
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Understanding the Electromagnetic Spectrum and Its Effects on Your Body
Before discussing the various forms of light therapy, it is important to have a basic understanding of light wavelengths and their properties.
The electromagnetic light spectrum is approximated in nanometric (nm) wavelength measurements as follows:
- Ultraviolet (UV, sunlight): 10 – 380 nm
- Violet: 380 – 450 nm
- Blue: 450 – 495 nm
- Green: 495 – 570 nm
- Yellow: 570 – 590 nm
- Orange: 590 – 610 nm
- Red: 610 – 700 nm
- Near-infrared (NIR): 700 – 900 nm
- Infrared: 900 – 1400 nm
The boundaries between light ranges are not static or precise. The spectrum is continuous, so there is no exact, definitive border for the beginning or end of each color range.
Infrared light is invisible; however, because everyone is unique, one person’s ability to see a given wavelength might differ from that of another. Light wavelengths up to 1050 nm are potentially visible to some people, although it is believed that around 900 nm is the cutoff point of visible light for most people.
Prevalent Types of Light Therapy
Lowest in wavelength on the spectrum, UV light (sunlight) is a great source of Vitamin D. UV rays, however, are also known to cause wrinkles, age spots, and skin cancer. Natural UV light is healthy in small doses, but the risk of harmful side effects is high.
Short green light shows some efficacy in treating migraines and other pain, but its effects are not largely proven. Green wavelengths can have negative side effects similar to those of UV rays.
The most common wavelengths used in light therapy are blue and red.
What Is Blue Light Therapy Good for and What Are Its Side Effects?
We encounter blue light every day. It is emitted from electronic devices and bright white LED bulbs commonly used in our homes. Blue light exposure is known to have negative physical effects.
Blue light wavelengths (400 to 495 nm) are shorter than red LED (610 to 700 nm) and red NIR (700 to 900 nm). Blue light stimulates your brain rather than soothing it. Due to the near-constant use of electronic devices in today’s world, blue light exposure has increased significantly in recent years.
Exposure to blue light can sometimes be good. Blue light has some positive therapeutic effects; most notably in treating acne, as it is proven to kill acne-causing bacteria. Blue light also stimulates and prepares your brain for the upcoming day, helps you stay awake and alert, lengthens your attention span, and helps you to focus.
Blue light exposure before bedtime, however, signals your brain to remain at attention when it should be starting to relax. Blue light disturbs your natural circadian rhythm  , the internal biological clock that regulates your sleep cycle and repeats approximately every 24 hours in conjunction with the earth’s rotation. Melatonin production is suppressed, so your sleep patterns are thrown off balance.
Most people would benefit from less blue light exposure, not more. Consider wearing blue-blocking glasses or using an app that filters blue light to combat its effects.
Blue light has many negative side effects including headaches, decreased attention span, and poor sleep quality.
What Is Red Light Therapy Good for and What Are Its Side Effects?
Some conditions that red light therapy can treat or assist with are:
- Ocular health
- Pain relief
- Weight loss
- Depression and anxiety
- Injury recovery time
- Cognitive abilities
- Athletic performance
- Overall body health
- Thyroid function
How Does Red Light Therapy Work?
Red light therapy taps into your body’s innate healing powers by stimulating cellular change.
Red light wavelengths penetrate your cells’ mitochondria (the part of the cell that powers biochemical reaction and energy production). The mitochondria stimulate the creation of the organic compound adenosine triphosphate (ATP), which is your body’s primary currency of cellular energy transfer.
ATP boosts the energy level in the cells of your tissues and organs. Energized cells trigger elevated oxygenation, better circulation, and heightened immune response. These effects work together to jump-start your body’s natural healing powers, thus promoting more expedient recovery and improved overall health and well-being.  
Does Red Light Therapy Produce Negative Side Effects?
No. Studies have proven that red light therapy produces no long-term side effects in the treatment of:
- Vision problems 
- Cancerous tumor growth 
- Facial Skin rejuvenation 
- During pregnancy 
- Relief of osteoarthritis and rheumatoid arthritis  [10}
No significant side effects of red LED or NIR light therapy have been reported in any treatment incidences.
Potential minimal and temporary side effects of red light therapy reported (in rare instances) include eye strain, light sensitivity, headache, and skin tightness. These are rare in occurrence and have no long-term impact. If you begin to experience any of these effects during therapy, discontinue your session and resume at another time.
While red LED and NIR light wavelengths pose no danger, infrared light is thermal (heat-producing) and penetrates your skin to a much deeper level.
Because it is thermal, infrared light can burn your skin, damage your eyes, and even cause organ damage. Infrared light must be administered with the utmost care. It is generally used only to treat serious diseases and conditions, and its wavelengths are not readily available in at-home therapy devices.
With your own red light therapy device, you can immediately begin to experience rapid healing benefits in the comfort and privacy of your own home.
-  harvard.edu - Blue light has a dark side (opens in a new tab)
-  nih.gov - Blue Light & Circadian Rhythm (opens in a new tab)
-  nih.gov - Anti-inflammatory effects of RLT (opens in a new tab)
-  nih.gov - LLLT in Skin (opens in a new tab)
-  iop.org - pdf file (opens in a new tab)
-  nih.gov - Safety of RLT wrt Cancer (opens in a new tab)
-  inbmedical.com - Anti-aging Benefits of ILT (opens in a new tab)
-  ndnr.com - Acne During Pregnancy (opens in a new tab)
-  nih.gov - Relief from pain in elderly (opens in a new tab)
-  nih.gov - LLLT in the treatment of rheumatoid arthritis (opens in a new tab)