Safety of Red Light Therapy: Contraindications and Side Effects

The safety of using Red Light Therapy at home is a common concern among people interested in its benefits. Let's delve deeper into its safety profile, possible contraindications, side effects, and important precautions to consider. Always consult your doctor about your specific health concerns before beginning any therapy, including red light therapy.

Red Light Therapy: Contraindications and Side Effects

Safety from Sunlight

A basic question when considering the safety of red light therapy often concerns our tolerance for sunlight. If you can tolerate moderate exposure to sunlight for about 20 minutes without adverse effects, chances are you can safely benefit from LED red and near-infrared (NIR) light therapy. Since approximately 42% of sunlight is made up of Red and NIR light, our bodies have adapted to absorb and benefit from these wavelengths.

While excessive exposure to UV or Blue Light in sunlight poses risks such as burns, the safety profile for Red and Near Infrared light differs. Red light therapy within the range of 600nm to 1100nm allows us to reap the health benefits of sunlight without the potential damage caused by UV rays.


Possible Contraindications

Several articles and sources outline specific contraindications to red light therapy. In the event that one or more of these contraindications are relevant to you, it is essential to evaluate this on a case-by-case basis in consultation with a medical professional.

Eye Exposure: Direct exposure of the eyes to red light or near-infrared light should be avoided as it may cause damage to the retina. Keeping the eyes closed or wearing protective glasses is essential to protect the eyes during treatment.

Cancer: Red light therapy is used to improve the proliferation of cells in a wound. Stimulating cell division could theoretically accelerate the growth or spread of cancer cells. There is some research to suggest that red light therapy can be used safely in tissues containing cancer, but this research is inconclusive. This 2018 review article by Dr. Hamblin discusses the many complexities of this topic.

No one should use red light therapy on cancerous tissue without permission from the oncologist.

Pregnancy: Pregnant women are advised to exercise caution, especially when exposing the abdominal area to the therapy. Although research shows that red light is not directly harmful to the fetus, caution is recommended due to limited studies on this topic.

Thyroid problems: Increased stimulation of the thyroid gland can worsen symptoms caused by a thyroid gland that is already overactive. People with hyperthyroidism should not use red light that can reach the thyroid gland without permission from their endocrinologist.

Epilepsy: People with epilepsy may be at risk of a seizure when using red light therapy, especially if poor quality red light panels are used. Inherent in almost every light source is a phenomenon called flicker. Flicker may be invisible to the eye, but it causes rapid fluctuations in the intensity of light. People with epilepsy may be sensitive to flicker in red light panels and may have a seizure if the flicker is severe or if they are particularly sensitive to it. At Helios we use flicker-free drives to remove the flicker from our panels.

Medications: Some medications can increase sensitivity to light. Because of this, red light therapy can irritate the skin or lead to a rash when using red light therapy. Although red light therapy is unlikely to have a significant impact on people taking photosensitizing medications, it is best to check whether the medications you are taking may increase your sensitivity to light and to talk to a doctor before using red light therapy if you are taking any of these medications.

Male genital tract: Although red light therapy is generally considered safe for treatments on the testicles (in men), caution should be exercised with excessively high doses.

Active Bleeding: In active bleeding, exposure to red light is not recommended due to its potential to increase blood circulation and therefore worsen bleeding.

Skin, Tattoos and Hair: People with dark skin, tattoos or excessive hair growth on treated areas should be aware of a higher absorption capacity of light, which can lead to discomfort, pain or even skin damage. Dosage and intensity should be adjusted for these individuals to avoid side effects.

By understanding these specific contraindications and evaluating them individually in consultation with a medical professional, one can minimize the risks and maximize the safety of red light therapy.

Skin and Thermal Effects: Although red light therapy is generally safe, exceeding specific skin temperatures for extended periods of time can lead to side effects such as skin redness, hyperpigmentation and heat-related problems. Moderation in intensity and dosage is crucial to avoid these skin-related side effects. Follow the manufacturer's instructions for this.

Studies on red light therapy rarely report side effects; still, some people with sensitive skin have reported temporary skin redness or discomfort after treatment. Responsible use, including reduced intensity and duration, can alleviate such reactions.


Man has adapted to the intensity of the sun in such a way that he is resistant to red and NIR light. In fact, it seems that we need some degree of absorption of red and NIR to live healthy and optimal lives, which is why photobiomodulation is such an important topic in clinical studies.

For eye safety, we have blink/deviation reactions, eye sockets, eyebrows, eyelashes and eyelids to protect us from the sun. And even our genitals have hair and are positioned to protect them from direct sunlight.

When we ignore our nature and stare at the sun, that's the problem. If we ignore our senses that our skin is feeling enormous heat, that is also a problem. The same goes for red and NIR. If we take the intensity into account and use some common sense safety techniques, most people should not experience any negative reactions.

Several of the documented contraindications such as eyes, thyroid, gonads - the dangerous effects come from direct exposure and high intensities and dosages. There has been some promising research showing that low-intensity light can be beneficial to these areas when applied properly.

Other contraindications such as Cancer and Pregnancy are clearly precautionary and should be assessed on a case-by-case basis in consultation with a doctor.

And as a final note, we often see people wrongly accuse near-infrared of causing dangers to the eyes, testicles, hyperpigmentation, etc. But in reality, we see many studies that have used red light to cause similar side effects and dangers - and vice versa NIR helps improve these areas when used properly.

So ultimately the safety profile for red and NIR (600nm-1100nm) light is highly dose dependent and not necessarily a particular wavelength within this range.

With these precautions in mind, moderate intensities and responsible use of red and NIR LEDs can be very safe for most people.


Before beginning any therapy, including red light therapy, always seek professional medical advice. This blog is for educational purposes only and is not intended as a substitute for medical advice or consultation.



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