The Dangers of Red Light Therapy: What You Need to Know Before Trying It

If you are on TikTok, you may have noticed your favorite creators using various red light therapy (RLT) devices. Celebrities like Kim Kardashian, Alisha Marie, and even actresses like Lili Reinhart, have reported using red light therapy for various wellness purposes, including skin health, hair growth, and relieving bodily pain.

However, with RLT's growing popularity on social media, it is natural to be weary about its safety. To address this, I have joined forces with my in-house research team to investigate what the science has to say about this technology. Additionally, I consulted experts on RLT to gather key considerations and practical advice for anybody curious about this technology.

What is red light therapy and how does it work?

Red light therapy is a technique that exposes skin tissue to low levels of red and/or near-infrared (NIR) light. While red light is part of the visible spectrum of light, near-infrared light is invisible to the naked eye.

This technology works on the body via a process called photobiomodulation, in which light stimulates cells within various tissues to promote certain biological processes.

Unlike other lights, such as ultraviolet (UV) light, red and near-infrared light have longer wavelengths and lower energy levels, penetrating the full thickness of the epidermis and dermis to reach the subcutaneous layer. Some of the benefits associated with this light include anti-aging effects, promoted wound healing, and reduced pain.

While red light therapy shows promising potential, it is important to note that research is still limited, and its effectiveness and safety need further investigation.

Proposed side effects of red light therapy: Deconstructing myths

While red light therapy shows potential as a non-invasive treatment in areas like pain management, hair growth, and skin rejuvenation, it is important to consider that these devices may also lead to side effects, particularly due to their limited research.

Eye strain

Red light therapy devices often come with glasses or other protective eyewear. We believe this is a good practice, especially for devices that use lasers. Lasers have more focused light than LEDs due to their coherence, an aspect that could potentially harm the eye. However, there is currently insufficient scientific research to indicate that red light therapy is dangerous for the eyes.

Headaches

Many websites report headaches as one of the most common side effects of red light therapy, although research in this field is quite limited. We found a study suggesting that individuals who already suffer from migraines may not find red light therapy comfortable. Nevertheless, it is unclear if this also applies to healthy individuals.

Medication interactions

Certain medications, including non-steroidal anti-inflammatory drugs (NSAIDs), diuretics, angiotensin-converting enzyme (ACE) inhibitors, beta-blockers, antidepressants, anxiolytics, retinoids, or hormonal contraceptives, may cause photosensitivity. This means that your skin reacts adversely to red light therapy, likely becoming red, swollen, burned, or itchy. If you take any medications, please consult your doctor to determine if a red light device is right for you.

Red light therapy considerations

After diving into some of the most common side effects of red light therapy, you may still be wondering if low-level therapy is right for you.

To help you make a decision, we have compiled a list of factors to consider before using these devices. Please view this list as a guide rather than a strict rule for using or avoiding red light therapy.

Pregnancy

As of now, no studies have investigated the effects of red light therapy on those who are pregnant and how it may affect the development of the fetus. That being said, it is advised to avoid starting any supplements, treatments, or therapies during pregnancy unless your doctor recommends them.

Cancer

Numerous studies have explored the safety of red light therapy on skin cancer with different results. For instance, an in vitro study found that red light phototherapy using LEDs inhibited melanoma proliferation and increased immune marker expression. Another study supported these findings, indicating that whole-body low-level laser therapy (LLLT) application (670nm) may be safe even when applied to malignant lesions.

Nevertheless, some research contradicts the positive findings. For example, a mouse model study reported that treatment with LEDs (642 nm) increased skin tumor proliferation.

It is important to note that these studies have been conducted in vitro or on animals, which means that results may not apply to humans. That’s why if you have a history of skin cancer, please consult with your healthcare provider about any red light therapy treatment.

Epilepsy

According to the North American Association of Laser Therapy, low-frequency pulsed visible light (< 30Hz) may trigger a seizure in photosensitive epileptic patients. That’s why, if you have epilepsy, it is best to consult your physician about these devices.

Thyroid function

There is not enough evidence to suggest that RLT could be dangerous for the thyroid. In fact, some studies have used red light therapy to act as an adjunctive therapy for some thyroid conditions, including autoimmune thyroiditis.

Moreover, a study with 30 healthy female participants reported no significant side effects on the thyroid and parathyroid glands. The participants wore an LED device on the neck for 16 weeks, and no major issues were reported either after the study or during the 8-week follow-up.

Skin color

Skin color and thickness may influence the reflectance of laser light, which means that those with darker skin will absorb more light than those with lighter skin.

According to two randomized controlled trials, red light from LED sources can be considered safe up to 320 J/cm2 for darker skin tones and up to 480 J/cm2 for non-Hispanic Caucasian individuals. That being said, The American Academy of Dermatology Association recommends a consultation with a dermatologist before introducing red light therapy in your routine, especially if you have colored skin.

How to choose safe red light therapy products?

Choosing a safe red light therapy device is not easy, especially given the overwhelming number of products on the market. To navigate this, I sought advice from professionals in the field. Matilde Almendral, a licensed esthetician, kindly agreed to discuss safety considerations and share her recommendations after several years of experience with RLT.

Before starting treatments with a client, I always evaluate their skin and overall health condition. For example, this low-level light therapy is not recommended for those with a history of skin cancer, pregnancy, or using photosensitive medications. So, my biggest advice before purchasing any device is to discuss it with a professional before starting.

Matilde Almendral

Almendral also clarified that while she understands that at-home red light therapy treatments are more comfortable, it is generally better to do them in a beauty clinic.

"I believe that visiting a clinic can help enhance the treatment's effectiveness and maintain its overall safety. However, for those that still want to do it at home, it is fundamental to consider wavelength, irradiance, type of light, and certifications," she added.

Almendral's key aspects aligned with important considerations of current red light therapy research. So, I encouraged her to elaborate on each one of the aspects further.

"I would advise choosing wavelengths between 625–780 nm for red light therapy and 780–1,400 nm for infrared light, as these ranges have scientific backing for their effectiveness. Additionally, you should select an irradiance of at least 100 mW/cm² to get good results," she explained.

We also discussed whether users should choose laser light treatment over LED for at-home use,

"In the clinic, we have both; however, I think it may be best to go for LEDs for at-home use. They can cover larger areas, are more affordable, and have fewer safety concerns than lasers. In any case, I would suggest avoiding low potency LEDs (<50 mW/cm²) because, in my experience, they tend to be less effective," Almendral shared.

Lastly, Almendral stressed the importance of buying devices with official certifications. She insisted during our conversation that this aspect is essential, especially since many customers look for budget-friendly solutions online,

"Always choose devices with certifications like CE or ISO, or those that have clearance from the FDA. Don't trust devices in online stores offered at low prices without certifications or quality assurance. While stores like Aliexpress, Temu, or even Amazon deliver cheap devices, they may not have your best interest in mind. Always shop from reputable providers," she concluded.

How to use red light therapy safely at home

While researching for this article, I stumbled upon many websites giving various tips on effectively using red light therapy at home. To gain a clearer perspective, I contacted Eva Nieto, a dermo-cosmetics nurse currently supervising red light therapy treatments in a beauty clinic.

Our chat with Nieto began much like with Almendral, with Nieto highlighting that those interested in RLT will most likely achieve better results in a clinic.

"I agree with Almendral that receiving your red light treatment in a clinic is preferable. This is not only because of safety measures but also because our equipment allows for greater personalization. If you use red light therapy at home, remember that the results will not be the same as those conducted by a professional. However, I do believe that at-home devices could be a nice addition to complement clinic treatments."

I also asked Nieto about key considerations and safety precautions to keep in mind when using red light therapy sessions at home.

"First things first, choose a quality device. As Almendral mentioned, choose a brand with official certifications and operate at an optimal wavelength. Next, make sure to follow your provider's guidelines for usage. I usually tell my clients to avoid using them more than 4 times per week, but it is always best to follow the device's specific recommendations."

Lastly, we ended our conversation with some practical advice from Nieto on how to use red light therapy devices.

Before using a red light therapy device, make sure your skin is clean. Do not use it on any wounds or injuries, and avoid applying skincare products like retinoids, glycolic acid, or salicylic acid before your session. I personally do not recommend sessions of more than 20 minutes, but check your devices' usage guidelines to be sure. If you want to use an RLT device on your face, avoid looking directly into the light and wear eye protection. Lastly, consult with a healthcare professional before starting red light therapy, especially if you have specific skin conditions.

Eva Nieto

The importance of professional guidance

There is still uncertainty about the safety and overall effectiveness of red light therapy. As we have highlighted throughout this article, research is limited, making it challenging to establish specific guidelines for its use.

Therefore, a consultation with a healthcare professional is crucial, especially if you have specific health conditions or are currently taking medication. Moreover, speaking with your doctor will help you get tailored advice and guidance on achieving the best results.

Final thoughts

We recognize that this article may not address all of your safety concerns. But frankly, we can't give clear-cut answers — research is still ongoing to uncover the potential of red light therapy. Moreover, everyone's skin is different, which means that individual reactions may occur.

What we can say with certainty is that if you want some guidance on red light therapy, your doctor is the only person who can provide it. Schedule a visit and take the opportunity to clarify doubts and receive personalized recommendations on using these devices.

Many influencers advertise red light therapy as an effective treatment for wound healing, hair growth, arthritis, acne, and other health conditions. However, it is important to stress that these recommendations often come from unqualified individuals, and most of your favorite creators are likely to receive a commission for promoting these devices. Therefore, avoid following social media advice and trust your doctor's expertise on RLT.

Lastly, if you decide to try red light therapy, always follow your manufacturer's guidelines on usage. Avoid using the product for longer than recommended, and clean it frequently to prevent bacteria buildup.