If you’re among the 35+ million men or 21+ million women in the United States who are losing their hair, you know how hard it is to slow thinning or balding, let alone regain natural hair growth. Creams, pills, and surgical treatments are often touted as solutions. These often come with side effects, however, causing many people to seek natural, safe, and non-invasive solutions. Red light therapy for hair loss shows great promise as a long-term answer ⁠— some studies have even shown it can reverse balding and restore natural hair growth.

Below we’ll review a few of those studies and clinical trials, show you how red light therapy works for hair loss, and show you how to use red light therapy at home for best results.

Red Light Therapy for Hair Loss

Hair loss takes a tremendous emotional toll on both men and women. Although some people rock the bald look, it’s not for every guy who suffers from male pattern baldness; and it’s rarely a desirable option for women who suffer from female pattern baldness.

If you’re having poor results or you’re dealing with side effects from common hair restoration treatments for balding, here’s why exploring red light could be a life-changing decision.

Red light therapy for hair loss is backed by scientific research. This completely natural and non-invasive treatment for hair growth has shown promise for reversing hair loss without disruptive side effects. Results indicate many benefits for human scalp hair including increased hair density and hair count.

What Is Red Light Therapy?

Red light is part of the visible light spectrum that makes up part of natural sunlight. Scientists have isolated the effects of each wavelength of visible and invisible light. Of all of the wavelengths studied, red light is mostly widely shown to support positive biological functioning in the human body.

Red light, which is also called low-level light therapy (LLLT), was discovered as a treatment for hair loss during the 1960s – and the discovery was accidental. A Hungarian scientist was conducting experiments with mice and had shaved the creatures’ backs.

After a series of red light sessions, the scientist was surprised to see fur growing around the shaved areas on the mice, and it was thicker than it had been before. That finding opened up exciting new scientific discoveries about the vast potential of red light therapy.

Today, the science has moved forward significantly, and now red light therapy uses high-power light-emitting diode (LED) bulbs to saturate the body with wavelengths of therapeutic light. Our bodies respond to the light in much the same way that plants respond to sunlight: by creating more energy at the cellular level.

Red light therapy has innumerable benefits. It has been found to be especially effective at treating balding; specifically, male and female pattern hair loss due to genetics, which is a condition known as androgenetic alopecia (AGA). Other main culprits that lead to hair loss include chronic stress or hormonal imbalances.

What Wavelengths Are Included in Red Light Therapy?

Red light therapy includes both red and near-infrared (NIR) light, which are among the longest of all wavelengths. Red light ranges from 630 nanometers (nm) to 700nm, whereas NIR light ranges from 700nm to 1100nm. Research has shown that light in the 630nm to 660nm range has the most powerful effects for treating hair loss.

Before starting red light therapy be sure to consult with your doctor. This is especially important if you have experienced sudden or dramatic hair loss, which can signal a serious underlying condition that goes beyond normal male or female hair loss.

It’s also important to talk to your doctor if you are currently taking any photosensitizing medications.

Types of Hair Loss: When Red Light Is Effective and When It Isn’t

Red light therapy can work on many common causes of thinning hair or balding include genetics (AGA, as mentioned earlier), chronic stress, poor nutrition, chronic inflammation, hormonal fluctuations (including due to pregnancy), thyroid disease, lupus, ringworm, auto-immune diseases such as alopecia areata and lichen planus, and over-styling (hair can be irreversibly damaged by harsh chemicals).

If you’re balding because of the effects of chemotherapy or other drugs, you’ll need to wait until you’re off these drugs before you can see any new hair growth. Once you’ve stopped the treatments, red light can work to halt chemical-induced hair loss and stimulate hair regrowth by promoting healthy cell functioning.

How Red Light Works to Regrow Hair

When you lose hair, the hair falls out but the hair follicles remain, although they stop producing hair and go dormant. Then, when you lose hair naturally (we typically lose 60–100 hairs per day out of hundreds of thousands), new hair is either slow to replace the lost hairs, the new hair is thin and weak, or hair growth stops altogether.

Therefore, the key is to get the hair follicles out of dormancy so they can perform their functions again.

What we see as “hair” is mostly a protein called keratin that makes up the hair shaft. Growth actually occurs under the surface in the follicles. Hair follicles are tube-like formations that anchor hair to the skin. At the base of each follicle is the hair bulb (the whole thing looks somewhat like a tall vase). At the bulbous part of the vase are the dermal papilla and the matrix; this is where hair begins to grow.

But, hair growth will slow down or stop completely if the cells in the hair follicles aren’t functioning properly. Here’s where red light therapy comes in to restore hair growth and increase hair thickness.

Increased Cellular Energy

Red light penetrates the skin to the base of the hair follicles. When red light photons absorb into the skin and reach the cells in the hair follicles, they interact with light-sensitive receptors in the mitochondria, which are energy-producing organelles inside the cells. This interaction stimulates the production of adenosine triphosphate (ATP), which is the primary cellular fuel.

Optimally fueled cells function better. They can do their jobs, replicate more successfully, and defend themselves against oxidative stress and any environmental pathogens. This directly affects their neighboring cells and the system or organ as a whole. As the hair follicles become functional again, the papillae will create more keratin, which results in hair growth.

Increased Collagen Production

Red light also increases the production of collagen, another type of protein found in the body. Collagen isn’t present in hair, but it acts as an antioxidant to fight damage caused by free radicals. These are harmful compounds that develop in the body during stress, or due to factors such as environmental pollutants or poor nutrition.

Free radicals damage hair follicles, which contributes to their inability to grow hair. Increased collagen means less oxidative damage, which can support normal hair follicle functioning.

Increased Microcirculation to the Scalp

Red light has been shown to increase the creation of new capillaries, which improves blood flow to the scalp and brings oxygen and nutrients to hair follicles. But it’s not just blood flow that improves; capillaries are also present in the lymphatic system, which removes waste that can lead to hair follicle damage.

A Massachusetts General Hospital study linked improved blood flow to the growth of thicker, healthier hair. Barbers and hairstylists have long encouraged men and women to massage their scalps as a way to increase blood flow. You could combine scalp massage with red light therapy to stimulate circulation in the scalp and “wake up” dormant hair follicles as well as improve cellular energy.

Are There Any Side Effects?

In the many studies done on red light therapy, virtually no side effects have been noted. Some people with sensitive skin may experience temporary redness or tightness of the skin. However, this is not a symptom of burns that you would get from overexposure to UV light. Red light does not cause burns.

Some hair restoration medication may cause unwanted hair growth, but that’s not the case with red light therapy. Because it stimulates your body’s natural growth processes, hair only grows back where it normally would and only in the treated areas.

In the next section, we discuss clinical trials on treating hair loss with red light therapy, specifically low-level laser therapy that uses low-powered visible red light laser devices.

Laser treatments are typically administered in clinical settings; the few laser devices available for consumer use are small, meaning that it would take an extremely long time to treat your entire scalp. However, LED devices that emit red light are just as effective as visible red light laser devices, and they are perfectly safe for use at home.

Clinical Trials

Red light therapy has been widely studied as a treatment for hair loss. Clinical trial after clinical trial supports red light therapy as a safe, painless, and effective treatment to promote hair growth. Here are a few of them:

Hair Growth Increases 37%

One study, conducted in 2014, involved 42 women aged 18 to 60 with AGA. The treatment group received 25-minute red light treatments daily for 60 days, while the control group received a sham treatment. At the completion of the study, the treatment group experienced a 37 percent increase in hair growth over the control group, and none of the participants experienced any adverse side effects.

Hair Growth Increases 51%

Even more impressive results were achieved during a 2017 clinical trial on women with AGA. A group of women aged 18 to 60 received red light treatments every other day for 17 weeks, while the control group received a sham treatment. Participants treated with red light experienced a 51 percent increase in hair counts compared with sham-treated control participants.

Thicker Hair Regrowth

A 2017 meta-analysis analyzed 11 studies on hair loss due to AGA. These combined studies had 680 participants (444 men and 236 women). Nine out of the 11 studies found statistically significant improvements in hair count, hair strength, and hair density (thickness) in both men and women.

Better than Other Treatments with No Side Effects

A 2018 meta-analysis reviewed 22 studies on AGA that compared red light therapy to other common treatments for hair loss, including top non-surgical treatments. Researchers concluded that red light therapy had a significantly greater effect at treating balding with no adverse effects.

Safe and Effective

A 2018 study by researchers from Taiwan found that red light therapy is an effective and safe treatment for male pattern baldness. The trial enrolled 100 men with AGA. Participants received three 30-minute treatments per week for 24 weeks on one side of the head, and a sham treatment on the other side of the head. The treated areas showed significantly greater hair density and hair count over the non-treated side, and no adverse side effects were observed.

Enhanced Dermal Papilla Cell Function

A 2019 study examined men with AGA and found that red light enhanced dermal papilla cell function. The participants were treated with 25-minute red light sessions every other day for 24 weeks. At the study’s completion, the researchers compared biopsied scalp tissue of patients with AGA before and after treatment.

Their analysis showed a statistically significant increase in proteins that indicate enhanced dermal papilla cell function; as a result, the researchers support the benefits of red light therapy for treating AGA.