What’s the Worst Thing About Red Light Therapy?

What’s safer and lasts longer than a Tylenol for pain relief?

Red light therapy reduces pain, plumps away wrinkles, shuts down inflammation.  But is red light therapy safe around cancerous tumors? 99 times out of a 100, the answer to the question is yes, red light therapy is safe around cancer.

The worst thing about red light therapy is that there is a tiny possiblity that it can, in some situations, make cancer worse. The exception occurs mainly in the test tube, and not in humans.

Admitting Imperfection is Uncomfortable

A completely accurate picture of my job interview
A completely accurate picture of my job interview

I was once on a job interview for a programming position. Five people interviewed me before the classic question finally came up: “What is your worst quality?”

I came prepared for this question and confidentially said, “I work too hard.”

I’d answered the “worst quality” question this way in the past with great success. “Ha ha ha, I see what you did there,” was the usual response.

But not this time.

“You work too hard?” This wasn’t a question, though. It sounded like a question on the outside, but on the inside, it was a demand to offer up a real fault, my actual worst quality.

My anxiety overcame my ability just to answer the question. I was prepared to joke the trick question away. I was not prepared to answer the trick question.

Anxiety blew the words out of my mind.
Anxiety blew the words out of my mind.

My mind went blank. I should have said, “Yes, I could manage my time better, I spend too much time on things that don’t matter,” and that would have answered the question.

Instead, I said, again, “I work too hard.”

Again, the hiring manager replied with a contemptuous and frustrated repeat of “You work too hard?”

The hiring manager was surprisingly angry that I didn't answer the question.
The hiring manager was surprisingly angry that I didn’t answer the question.

I was sure we had just done that. We were in a vicious cycle, circling the bowl, as it were.

I could have said, “I stay late at night, and then can’t work well in the morning, I don’t manage my time well,” and that would have answered the question. But he was frustrated and my mind was blank, so I said, “Yes, that’s my answer. I work too hard.”

This back and forth went on for what felt like an hour and a half. It was probably 2 minutes. Finally, because this stupid conversation was the only issue stopping them from hiring me, the hiring manager let go of his obsession. He offered me the job.

What if Your Answer is Too Good to be True?

Maybe my worst quality is that I don’t know what my worst quality is. So it’s not that I don’t have faults. It’s that I don’t see them as well as I should. Could that be my worst quality?

At a red light therapy academic conference I attended, an attendee asked Dr. Michael Hamblin, pre-eminent red light therapy researcher from Harvard and MIT, “Isn’t red light therapy contraindicated on cancerous tumors?

The first time I listened to Dr. Hamblin ask this question, I was surprised when he said, I wouldn’t worry about that.” Red light therapy, he said, “is a very effective therapy for cancer treatment side effects such as mucositis,” which are mouth sores from radiation therapy.

My thought upon hearing this answer was that just because red light therapy helps with cancer therapy side effects, that doesn’t make it safe to use around tumors.

The next time I was at a conference and this same question came up, Dr. Hamblin’s answer had changed.

Cell replication
Cell replication

“You might need to exercise caution right at the area of the tumor,” he said. “Because the therapy increases cell proliferation, which is something we want to avoid in this case.”

For almost 60 years, red light therapy studies showed that this technique has fantastic benefit with no side effects.

That stunning combination of tremendous benefit and virtually no cost is unlike any modality you could name.

Even supposedly safe Tylenol kills thousands ever year from the liver damage it creates.

How can red light therapy be such a success with such little downside?

What’s Right About Light

Light is not a drug, and this fact is tremendously important to understanding the pros and cons of red light therapy.

Mammals, including humans, use blue light to regulate or circadian rhythms, telling us when to wake and when to sleep.

Sun in blue sky
Sunshine allows us to create vitamin D

We use ultraviolet light to make vitamin D, a hormone in which virtually everyone away from the equator is deficient. The lack of vitamin D correlates with multiple sclerosis, fibromyalgia and depression.

Light doesn’t go into a cell to break one process in order to enhance another, thereby creating a workaround to disease and pain.

Light energizes the cells, it allows the blood to flow, and these hugely beneficial activities allow the body to heal itself.

It is because light is fundamental to mammalian life that red light therapy has virtually no side effects. I say “virtually,” because there are some contraindications, and because a light overdose can be problematic for some people. Neither of these are technically “side effects,” but we do need to put them into the “worst quality” bucket, and examine what they are.

What is Red Light Therapy’s Worst Quality?

Red light therapy opens blood vessels
Red light therapy opens blood vessels

“Worst” quality is dependent on your financial and health situation, but we can probably put “unwanted cell replication in already cancerous patients” as red light therapy’s worst quality.

To be clear, red light therapy cannot cause cancer. Period. End of sentence. Full stop.

Red light therapy opens blood vessels such as healing
Red light therapy opens blood vessels such as healing

I am referring to using red light on an existing tumor. If you point a red light therapy device at a cancerous area, you run the risk of increasing cell replication in that area.

Because cancer already is a case of unwanted cell replication, the red light ceases to be a therapy and turns into a menace in this case.

192 Answers to “Does Red Light Therapy Worsen Cancer?”

After reviewing the 192 results on pubmed.gov for (PHOTOBIOMODULATION) and (CANCER), the answer is: Red light therapy does not cause cancer. When used improperly at high energy, there could be a problem, but that is not red light therapy. Red light therapy does not use high energy.

Red light therapy inhibits cancer, and significantly reduces the side effects of powerful cancer treatments.

Red light therapy science
Red light therapy science

Dr. Hamblin reviewed the literature in 2018 (Photobiomodulation and Cancer: What Is the Truth?Opens in a new tab.). He concluded that red light therapy alleviated cancer therapy side effects and has been shown to reduce tumors rather than promote cell proliferation.

Oral mucositis is the onset of sores and sensitivity in the mouth from radiation therapy. Acute radiation dermatitis is the burns and skin cells death that emerge within three months after radiation. Dysphagia is difficulty swallowing, a common side effect of cancer therapy. Osteoradionecrosis is bone death from radiation therapy. Peripheral neuropathy is nerve damage causing pain, discomfort and normal function breakdown of processes such as urination and digestion.

Red light therapy eases the pain of these side effects. Here are just a few of the many studies showing this effect.

  • Low-level laser therapy [red light therapy] for oral mucositisOpens in a new tab. in children with cancer
  • Long-term safety of photobiomodulationOpens in a new tab. [red light therapy] therapy for oral mucositis in hematopoietic cell transplantation patients: a 15-year retrospective study
  • Photobiomodulation [red light therapy] therapy for the prevention of acute radiation dermatitisOpens in a new tab. in head and neck cancer patients (DERMISHEAD trial)
  • Evaluation of Efficacy of Low-Level Laser TherapyOpens in a new tab. [red light therapy]
  • The effect of photobiomodulation [red light therapy] on chemotherapy-induced peripheral neuropathyOpens in a new tab.: A randomized, sham-controlled clinical trial

Without saying whether red light therapy can encourage tumor cell proliferation, at least in the cases below, the therapy inhibits cell proliferation.

And, in fact, red light therapy can inhibit cancer cell proliferation. In one study below, red light therapy effectively treated oral cancer.

Red Light Therapy’s Effect on Test Tube and Human Cancers

Some studies found that red light therapy reduced cancer, but at least one study found that cancer got worse in the presence of this red and infrared light.

  • Mechanisms of PhotoBioModulation [red light therapy] (PBM) focused on oral mucositis preventionOpens in a new tab. and treatment: a scoping review
  • Safety and efficacy of photobiomodulation [red light therapy] therapy in oncologyOpens in a new tab.: A systematic review

Safety FirstAnother study found that the in vitro (test tube) increase in cancerous cells was not repeatable in humans. The same treatment in the test tube that increased cancer activity actually decreased cancer activity in vivo, or in the person.

A high dose of 150 joules correlated with longer survival rates. When irradiance (energy delivery) is too high, the oxidation peaks, causing damage. So higher energy red light therapy is potentially more of an issue than true low energy therapy. It’s important to re-emphasize that red light therapy is “low energy” delivery of light. Very powerful panels might give you faster treatment but could be teetering on a level that is too high to be healthy.

We Don’t Know, So Be Careful

The big question really is: “Does the use of red light therapy against cancer or cancer therapy side effects cause cancer proliferation?

No, red light therapy does not induce tumor cell proliferation, according to first study below, but did induce tumor cell proliferation in the second study, below. But researchers examining those studies could not determine what was different about the unwanted proliferation parameters. So their advice is, “We don’t know, so be careful.”

What is Red Light Therapy’s Worst Quality?

He worked his elbow too hard. He should try red light therapy for that.
He worked his elbow too hard. He should try red light therapy for that.

The incredibly small evidence that red light therapy can make cancer worse is restricted to the test tube and a single outlier case, whereas the massive evidence that red light therapy reduces cancer and treatment side effects is repeatable and confirmable.

Clearly the worst quality of red light therapy is that it works too hard.

Caroline Bogart

I research the bloody hell out of everything that interests me, then translate it into blog posts to solidify my knowledge and share the information.

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