In the wellness and spa industry, light therapy is often marketed as a cure-all, an easy and noninvasive solution to everything from wrinkles and joint pain to energy slumps and injury recovery.
But like many things in life, more is not always better, and not everyone is a candidate for this modality. While photobiomodulation (PBM) therapy, more commonly known as red and near-infrared light therapy, has numerous studied benefits, it is a precision-based science that requires thoughtful application, responsible training, and careful consideration of client history.
As a Board Certified Light Therapist working closely with a variety of LED therapy devices, I have seen firsthand the results this technology can produce.
I have also seen what happens when it is misused.
Understanding Light Therapy’s Mechanisms
Light therapy works by delivering specific wavelengths of light to the body, most often within the red (630 to 660 nm) and near-infrared (810 to 850 nm) ranges. These wavelengths penetrate the skin and stimulate mitochondria, triggering a photochemical reaction that increases ATP production.
ATP is the body’s cellular energy currency. The result is improved circulation, reduced inflammation, accelerated healing, pain relief and enhanced skin quality.
This effect is dose-dependent and governed by the Law of Biphasic Dose Response, also known as the Arndt-Schulz Law. A small dose of light may stimulate repair and regeneration, but too much can inhibit those same biological processes.
Overexposure can lead to cellular fatigue, increased inflammation, or, in sensitive individuals, what is known as a Herxheimer reaction.
What Is a Herxheimer Reaction?
A Herxheimer reaction, or “healing crisis,” occurs when the body begins to detox or shift biologically faster than it can eliminate waste. In the context of light therapy, this may manifest as headaches, nausea, fatigue, skin breakouts, body aches, or flu-like symptoms following sessions.
While this is not necessarily dangerous in healthy individuals, it signals that the body is overwhelmed. Pushing through it without rest or adjustment can delay healing rather than promote it.
Herx responses are more likely when high doses are introduced too early in a therapy program, when clients are already immunocompromised, or when hydration and detox pathways are insufficient.
Practitioners must recognize the signs and understand that more light is not always better. The common misconception is that there is no such thing as over-doing it, and that your body will simply just not absorb the light once it has gotten its fill.
Who Should Not Use Light Therapy?
Contrary to popular belief, red light therapy is not universally safe. Devices used in wellness settings today, even those labeled “non-medical,” emit biologically active wavelengths that interact with tissue and can influence medication pathways, vascular dynamics, and cellular responses. This is why proper intake and informed consent are essential.
Clients should avoid light therapy or consult a physician before use if they:
- Have chronic low blood pressure, or are taking blood pressure medication
- Have a history of epilepsy or seizure disorders
- Are actively bleeding or have areas of hemorrhage
- Are pregnant or breastfeeding
- Have active carcinomas or untreated malignant tumors
- Are taking blood thinners or nitrate medications
- Have active infections or contagious skin conditions
- Are recovering from recent surgery or open wounds that require medical oversight
Even in the absence of these contraindications, some individuals with autoimmune disorders, photosensitivity, nerve damage, diabetes, are seeing a doctor for certain medical conditions or have impaired lymphatic function may require a slower, carefully observed introduction to light therapy or may be told to avoid it completely.
This is particularly important when using full-body LED systems or combining with heat-based modalities like infrared saunas or wellness pods.
Modified Tanning Units And Regulatory Risk
A growing number of salons have been modifying UV tanning beds by replacing original fluorescent lamps with red light therapy tubes or LEDs. While this may seem like an efficient way to expand services, it directly conflicts with FDA regulations.
According to a 2011 memorandum from the U.S. Food and Drug Administration, this practice creates a new class of device that is no longer considered 510(k)-exempt and must undergo premarket clearance or approval.
Salons promoting red light therapy in modified tanning units for purposes such as skin rejuvenation, wound healing, or collagen stimulation may be marketing an adulterated and misbranded device under the Federal Food, Drug, and Cosmetic Act. This can expose business owners to significant regulatory, legal, and insurance risks.
Even when well-intentioned, these modifications often underdeliver. Standard red light fluorescent tubes typically produce only a minimal skincare-level dose, not a therapeutic one.
On the other hand, some high-output LED systems are capable of delivering more than 60 joules of energy per session, which exceeds the optimal therapeutic threshold for many users. Without knowing the actual output of your device, there is a serious risk of either underperforming or overexposing clients.
Practitioners must be transparent about what their equipment can safely and effectively deliver. Accurate dosing and realistic claims matter.
When Overuse Becomes Harmful
Just because a client feels better after one red light session does not mean they should double up the next day, often daily use is advised against to allow your body time to digest. There is a common misconception that more exposure will lead to faster or enhanced results.
In reality, photobiomodulation is cumulative, not exponential. Once cellular saturation is achieved, continued exposure does not provide additional benefit and may even suppress mitochondrial function or overstimulate the nervous system.
This is especially relevant in spa settings where self-guided or unsupervised use is common. Without structured protocols, it is easy for well-meaning clients to overuse red light, particularly when layering it with other recovery tools like cryotherapy, massage, or sauna therapy.
Ethical Use Starts With Education
Informed consent is foundational in my practice. Each client signs an agreement outlining the scope of red light therapy, potential risks, my credentials, and a list of medical red flags. This is not about restricting access. It is about prioritizing safety, transparency, and professional accountability.
Light therapy is a powerful tool. It is not passive or risk-free. While red and near-infrared light can support healing, recovery, and resilience, it must be applied with knowledge, intention, and respect for biological limits.
It is time to move beyond one-size-fits-all marketing and embrace light therapy for what it truly is: a scientifically validated modality that must be delivered with skill and care to create lasting change.
