Red Light Therapy Side Effects & How To Minimize Them

Red Light Therapy Side Effects & How To Minimize Them

Before answering the question, “What are red light therapy side effects?”, it is pertinent to know what the therapy is all about and the purposes for which this therapy may be used. 

Red light therapy, alternatively known as non-thermal photobiomodulation (PBM), Low-level laser (light) therapy (LLLT), soft laser therapy, or cold therapy is an evolving technology to treat multiple conditions. This includes but is not limited to the restoration of various body functions, pain relief, skin rejuvenation, fat control, and even working on your hormones such as increasing your testosterone level and boosting fertility [1, 2]. The therapy has been proven to reduce inflammation as well.

Nowadays, the use of high dosage medicines, injections, and chemical procedures to restore beauty or to control pain is common. People are spending thousands of dollars for this purpose.  However,  we must understand that too much intake of antibiotics or other pills can affect kidney function, and too many chemical masks can peel off the layers of your skin and merely give temporary benefits. 

Because of this, people are now moving toward red light therapy to avoid the side effects of chemicals and medicines. However, doubts regarding the efficacy of red light therapy also exist. The concern is genuine as one should not be wasting bucks to cause harm to the body. 

Here are some pieces of evidence in this article that discuss some side effects of red light therapy.  We will also analyze if the side effects can be avoided with the right precautions and how to take the advantage of this technology effectively. Keep reading for details.

What Is Red Light Therapy? 

Red light therapy or low-level laser therapy (LLLT), also known as photobiomodulation, came into being soon after the invention of the ruby laser in the 1960s [3]. A worker at the University of Budapest experimented with this on mice and figured out that the use of this therapy helps grow hair faster and aid in wound healing. This eventually evolved into successfully experimenting and practicing low light laser therapy on humans for joint problems, wound healing, neuro disorders, pain relief, and inflammation.

During this therapy, the affected part is exposed to a low level of red or near-infrared light for treating the ailment. The mitochondria of the cells get activated and during this time, the therapy starts working [3].

Controversies regarding this therapy are based on certain factors such as the intensity of heat, varying wavelengths, and timing for which the therapy is used. Certainly,  an excess of everything is bad. For example, researchers suggest that using an RLT device for 15 to 30 minutes every day is sufficient to get the optimal benefits for the skin. But do not get obsessed with it if you want to achieve desirable results. 

How to Minimize Red Light Therapy Side Effects

Improper use of red light therapy may have some effects. Here are some red light therapy dangers that you may encounter in case you do not know how to use the therapy properly. 

Burns and Blisters

There are some cases where people report burns and blisters after using a red light therapy unit. When investigated, it became evident that the use of the device was continuous without considering time. Either the person fell asleep or was trying to optimize the benefits. What if the doctor suggests a medication and we eat it all at once to get well and to be able to attend a meeting for tomorrow? No one should do that at any cost. 

The same goes with red light therapy. You can only attain benefits if you follow the directions of your doctor or the device’s manual and be careful while you’re using your RLT device. This therapy is called low-level laser therapy or cold therapy only because a very small amount of heat is used which is bearable and can activate energy within the cells. Red light skin therapy side effects will nearly be zero depending on the user’s awareness and cautiousness. 

Possible Eye Strain

Eyes are the most sensitive parts of our body and it is believed that using any kind of light for your eyes may be risky. Yes, true but which wavelength and intensity are harmful is another question. Red light therapy is widely used today to treat certain eye problems such as methanol-induced retinal damage, age-related macular degeneration amblyopia, and many more [4]. Its benefits for the eyes are manifold. 

red light therapy side effects

The finding of another research paper suggests that using looking at a deep red light for three minutes a day can significantly improve declining eyesight. Significant improvement in the retina’s photoreceptors was noted while eyes were exposed to 670 nanometres (long wavelength) deep red light. They also observed that wavelengths of 650 to 1000nm improve mitochondrial performance [5]. 

This means that other wavelengths can possibly inflict some kind of harm. In the case of your eyes, only rely on the instructions of your doctor. Also, it is good that light therapy on the eyes is done before sun exposure to prevent eye degeneration.

Red Light Therapy and Cancer

There are also concerns among people that as red light therapy can activate cells, it can therefore also proliferate cancerous cells. This may be possible if malignancy is already present within the body.  The answer to this question is present in a scientific study that investigated whether low-level light therapy (LLLT) would promote tumor growth [6]. The results suggested that no changes in tumor sizes were observed for consecutive 37 days of the use of LLLT.  This study concluded that red light therapy is safe to be used even when the cancerous lesions are present. 

However, we suggest that the best thing to do is to seek your doctor’s advice before using any home-based red light therapy device. In particular, people who have skin cancer should not experiment on their own, no matter how safe it seems to be. 

Risks for Photosensitive Skin

Photosensitivity means your skin is extremely sensitive when exposed to any kind of light resource. This varies from person to person. Some people are in the habit of working for hours and hours in sunlight but many are at the risk of sunburn even when exposed to sunlight for a few minutes. Red light therapy may cause skin irritation or redness to such people. If you think your skin is sensitive to any kind of light, go for a skin sensitivity test before using an RLT device. 

Suggested Post: 9 Benefits of Red Light Therapy for Skin

Insomnia and Headache

There are cases where people reported sleep problems and headaches while using red light therapy. This happens when people expose themselves excessively to these devices or they are continuously staring at the RLT units without considering the recommended time. 

While using it to fix a particular skin issue, protective goggles may be used so that the timing, say 30 minutes of procedure, does not inflict any pressure on your eyes. This is just as if you are using sunglasses while lying in front of sunlight for tanning purposes. Your body will get vitamin D and a tanning effect from the right amount of sunlight but you need to protect your eyes at the same time. 

Pregnancy and the Use of Red Light Therapy

Although there is no scientific research available on red light therapy’s negative consequences during pregnancy, pregnant moms should still be extra cautious while using red light therapy or in fact, when taking any kind of medicine without consulting their doctors. 

However, there’s also an interesting finding which reveals that light therapy is used to reduce depression during pregnancy while not inflicting any harm to the fetus as compared to using pharma products [7].

Cheap and Fake RLT Devices

Cheap and fake products should be avoided. It is important to find a reliable and authentic RLT device for you. A high-quality device with the right mechanism of filters is necessary to get the desired results. Otherwise, you will end up buying a problem for you.  

This will just need a little bit of research or talking to someone who is already using the products. Do not just run and buy a product because you have heard about its benefits. At the end of the day, your health and body matters and you wouldn’t want to make an uninformed hasty decision. 


Red light therapy is a new and safe technique for treating a variety of issues. From treating skin issues to handling depression, red light therapy has minimal or nearly no side effects. Blisters, burns, depressions, or irritability only occur when the devices are not properly used or when individuals are sensitive due to the use of a particular medicine. In some cases, people are genetically vulnerable to light due to photosensitivity. 

If the measures suggested above are honestly employed, red light therapy can be used without any harm. This primarily includes consulting your doctor, being careful of the intensity, and not being obsessed with using the product frequently. 

Written By Matthew Caldera

Matthew Caldera is the founder and CEO of nuYOU LED, a leading provider of red light therapy devices. As a dedicated biohacker and RLT specialist, Matthew aims to make science-backed information about red light therapy and self-improvement more accessible to everyone. To achieve his goal, Matthew uses up-to-date research materials and converts them into easily digestible articles, answering frequently asked questions of those interested in the power of red light.

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  1. Wunsch A, Matuschka K. A controlled trial to determine the efficacy of red and near-infrared light treatment in patient satisfaction, reduction of fine lines, wrinkles, skin roughness, and intradermal collagen density increase. 2014 –
  2. Avci P et al. Low-level laser (light) therapy (LLLT) in the skin: stimulating, healing, restoring. 2013 –
  3. Chung H et al. The nuts and bolts of low-level laser (light) therapy. 2012 –
  4. Geneva I. I. Photobiomodulation for the treatment of retinal diseases. 2016 –
  5. University College London. (2020, June 29). Declining eyesight improved by looking at a deep red light. 2020 June 29 –
  6. Myakishev-Rempel M. A Preliminary Study of the Safety of Red Light Phototherapy of Tissues Harboring Cancer. 2012 –
  7. Wirz-Justice A et al. A randomized, double-blind, placebo-controlled study of light therapy for antepartum depression. 2020 April 5 –

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