Red Light Therapy Dangers: What You Need to Know

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Red light therapy (RLT) has gained popularity in recent years for its potential benefits for skin health, wound healing, pain relief, and more.

However, as with any treatment, it’s important to be aware of possible risks and side effects.

In this post, we’ll take an in-depth look at the potential dangers of red light therapy and what the research says about its safety.

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Red Light Therapy Dangers

There is a lot of discussion around whether red light therapy has dangerous downsides.

For the most part, people are comfortable using red light but face limitations around affordability.

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The good news is that there are several studies and anecdotal reports that demonstrate that red light therapy is safe when used responsibly.

Can Red Light Therapy Cause Cancer?

One of the most serious potential dangers that people wonder about is whether red light therapy can cause cancer.

A 2021 study on mice found that under very specific conditions conducive to tumorigenesis, red LED light treatment promoted the development of skin tumors.

However, it’s important to note that this was a single animal study looking at a very particular circumstance.

In contrast, many other studies show that red light therapy may actually reduce the incidence of various cancers. Much more research, especially in humans, would be needed to determine if RLT could promote cancer growth.

Some evidence even suggests red/infrared light may have a protective effect against the cancer-causing impact of UV light.

Overall, the bulk of the research so far points to red light therapy likely reducing cancer risk rather than increasing it for most people. Still, more studies are needed to say definitively.

Red Light Therapy Side Effects

While major adverse effects from red light therapy appear to be rare, there are some potential side effects to be aware of.

Eye Damage

Red light may benefit eyesight, but prolonged exposure, especially to near-infrared, could potentially harm the eyes.

It’s recommended to keep sessions to 3-6 minutes, close your eyes during use, and wear protective goggles.

On the other hand, people who use red light therapy to improve eye health, like Joe Rogan, report looking directly into the red light. However, this practice is not backed by existing scientific literature.

Those with pre-existing eye conditions should consult their ophthalmologist before use.

Related: Andrew Huberman Red Light Recommendations

Skin Reactions

While red light therapy is generally safe for the skin, there are some potential reactions to be aware of, especially with overuse or misuse.

Burns, redness, and pigmentation changes can occur if the light is too intense, held too close to the skin, or applied for an excessive amount of time.

Most devices come with specific instructions on the optimal distance and duration for treatment.

A general rule of thumb is to position lights about 6 inches from the body and limit sessions to a maximum of 10-20 minutes. However, this can vary depending on the specific device and individual sensitivity.

Some redness is common after treatment and typically resolves within a few hours.

More severe burns or blistering can occur with overexposure.

The best way to avoid adverse skin reactions is to start slow, follow the device instructions carefully, and don’t assume that more is better.

If you have sensitive skin or a history of photosensitivity reactions, do a patch test on a small area before applying it to the whole body or face.

Dizziness/Rapid Heartbeat

Some people report feeling dizzy, lightheaded, or having a rapid heartbeat during or after red light therapy sessions. While the exact cause isn’t clear, it may be due to changes in blood flow, a sudden drop in blood pressure, or an increase in circulating nitric oxide levels stimulated by the light.

These symptoms are more likely to occur if treatment sessions are too long, the body gets overheated, or the individual has an underlying health condition. Those with low blood pressure, heart disease, or a history of fainting or dizziness should use extra caution.

In general, people with heart conditions, a history of syncope, or those taking medications that increase photosensitivity should check with their doctor before starting red light therapy. Sessions may need to be shorter or less frequent for these individuals to minimize the risk of adverse reactions.

Is Red Light Therapy Safe Overall?

Is Red Light Therapy Safe Overall?

When used as directed with proper eye protection, red light therapy appears to be safe for most healthy adults.

A 2017 review of the research concluded:

“The available literature strongly suggests that PBM [photobiomodulation] therapy is safe for various indications in ophthalmology…in physically healthy unmedicated persons.”

It’s important to note that while the available evidence suggests RLT is likely safe for most people when used properly, more long-term human studies are needed to establish its safety profile firmly.

The potential risks and benefits should be carefully weighed on an individual basis.

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As always, it’s best to follow device instructions closely and start with shorter treatment times.

Don’t exceed recommended treatment times, thinking “more is better.”

If you have any concerning symptoms or pre-existing health conditions, it’s a good idea to talk to a doctor to determine if RLT makes sense for you.

Related: Bryan Johnson Red Light Therapy Insights

Red Light Therapy Detox Symptoms

Red Light Therapy Detox Symptoms

Have you heard people talking about experiencing “detox symptoms” when they start red light therapy?

Things like fatigue, headaches, or skin breakouts?

The idea is that as RLT energizes your cells and gets your blood flowing, it’s also releasing built-up toxins, which can cause some temporary discomfort.

But here’s the thing: the concept of “detox” is a bit of a murky one. There’s not a lot of clear scientific evidence to back it up. And many of these supposed detox symptoms could easily be caused by other factors that have nothing to do with RLT.

So, while it’s possible you might feel a little off when you first start RLT, it’s hard to say for sure whether that’s a “detox reaction” or something else entirely.

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The good news is that if you do experience mild symptoms, many users report that they can clear up on their own within a few days as their bodies adjust. Just stay hydrated, eat well, and get plenty of rest.

But if you’re really not feeling well or your symptoms are severe, it’s best to hit pause on the red light therapy, at least temporarily.

Can You Overdo Red Light Therapy?

Can You Overdo Red Light Therapy?

We get it, when you find something that works for you, it’s tempting to go all in.

But, like with most things in life, you can definitely overdo it with red light therapy.

While red light therapy is generally safe, too much exposure can lead to side effects like eye strain, skin irritation, or making existing conditions worse.

This is especially important if you’re using an at-home device. It can be easy to get carried away and do longer or more frequent sessions than you should. And if your device is high-powered or includes UV wavelengths, that can be particularly risky.

So what’s the sweet spot? Most experts recommend capping your sessions at 20 minutes, once or twice a day, 3-5 times a week.

When in doubt, start low and go slow.

Can You Feel Sick After Red Light Therapy?

Feeling sick after red light therapy isn’t a common side effect, but it can happen.

Some people report nausea, dizziness, or flu-like symptoms, especially when they’re just starting out.

As we mentioned in the detox section, this could potentially be a sign that your body is adjusting to the effects of the light.

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If you do feel sick after RLT, the best thing to do is stop treatment and consider giving your healthcare provider a call.

Another thing to keep in mind: RLT can be dehydrating, especially if you’re doing it in a warm room or with a device that gives off heat.

Dehydration can make you feel dizzy, nauseated, and headachey, so be sure to drink up before, during, and after your sessions and consider supplementing with electrolytes.

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What Are the Signs of Too Much Red Light Therapy?

So, how can you tell if you’re overdoing it with RLT?

Here are some common red (pun intended) flags to watch out for:

  • Eye strain, pain, or changes in vision
  • Skin redness, irritation, burning, or blistering
  • Existing skin conditions like eczema or rosacea getting worse
  • Headaches or migraines
  • Nausea, dizziness, or feeling lightheaded
  • Fatigue or trouble sleeping
  • Increased sensitivity to light

If you notice any of these signs, it’s a good idea to scale back on your RLT sessions or take a break altogether.

Another important thing to pay attention to is how you feel overall after RLT. If you consistently feel worse instead of better, that’s a sign that RLT might not be the right fit for you, or that you need to tweak your treatment plan.

Is It Bad to Do Red Light Therapy Every Day?

You might be thinking, “If a little RLT is good, then a lot must be even better!”

But that’s not necessarily the case. While some people may benefit from daily sessions, for most of us, it’s not needed and might even do more harm than good.

Most studies on RLT use treatment plans that range from 2-5 sessions a week with rest days in between.

If you’re hitting the light every day, your cells might not have enough time to recover and regenerate.

Plus, over time, your body can start to get used to the effects of RLT. If you don’t give it occasional breaks, you might hit a plateau where you stop seeing progress. Mixing up your schedule with rest days or longer breaks every few weeks can help keep your body on its toes.

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Now, the best frequency for YOU will depend on a few things – like what you’re using RLT for, the device you’re using, your age, and your overall health.

For example, some skin conditions might do best with short daily sessions, while deeper issues like muscle or joint pain might respond better to longer, less frequent treatments.

A good rule of thumb is to start with 2-3 sessions a week and work your way up if needed.

Medical Advice Disclaimer


The information, including but not limited to text, graphics, images, and other material contained on this website, are for informational purposes only.

No material on this site is intended to be a substitute for professional medical advice, diagnosis, or treatment.

Always seek the advice of your physician or other qualified health care provider with any questions you may have regarding a medical condition or treatment before undertaking a new health care regimen, and never disregard professional medical advice or delay in seeking it because of something you have read on this website.

About the Author

Drew Wilkins is a fitness and nutrition expert with a Master's in Biokinesiology (emphasis in Sports Science) from the University of Southern California and over a decade of experience as a personal trainer, nutrition consultant, and wellness coach. An avid surfer and soccer player, he brings a unique perspective to his research, advocating for a balanced approach to health that includes physical fitness, nutrition, and mental well-being.

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