Red light therapy is a proven wellness therapy that affects energy production at the cellular level. With red, infrared and blue light having so much success, what kind of red light grows hair?
Red light is the most scientifically supported light to regrow lost hair, but infrared and even blue can also stimulate hair growth. Most studies on androgenetic alopecia (male pattern hair loss) support using red and infrared for hair loss.
When red light therapy does work, it has an over 90% success rate. However, many types of hair loss do not respond, so make sure you have the right type before buying a hair growth light.
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Red Light Therapy for Hair Loss Does Not Work for Everyone
Only certain types of hair loss resend to red light therapy. Ensure you have one of these hair loss types before buying a hair growth device.
Red light therapy grows hair for some patterns, but not all of them. Compare your hair loss pattern to the pictures in the male and female hair loss scales. If you are not sure if you are a good candidate, contact the red light therapy company for help.
Women use the Ludwig-Savin Classification and men use the Norwood-Hamilton Classification. The patterns in the middle of each scale respond best to red light therapy. Red light therapy grows hair on women in four out of the nine female hair loss patterns; and seven out of 12 male hair loss patterns.
If you have the right hair pattern, then red light therapy is good for hair growth. When used correctly and on responsive hair patterns, red light therapy grows hair over 93% of the time. Red light therapy does not work for some people, so it is important you check your hair loss type before buying a device. See the section above for more information on how to do this.
Red light therapy got its start when a researcher noticed that red laser light grew hair on mice. The field of red light therapy is now called Low Level Light Therapy (LLLT) or photobiomodulation (PBM) began with the use of red light to grow hair.
Red light therapy hair growth companies advise checking your hair loss type against the male and female charts before committing to a device.
You Can Grow Hair At Home
The hair growth red lights you can buy for at-home use are as good as any treatment at the doctor’s office, with the possible exception that your treatment times at home might be longer per session.
When higher-powered lasers were the only hair growth delivery system, there was no at-home option. Now that low powered lasers and regular LEDs light the follicles, you have several choices for at home hair growth treatment.
There are so many choices, I do not want to overwhelm you, so let’s start with the big hair growth companies, and then I will show you a few interesting devices as well.
The best hair growth at-home device companies are HairMax, iRestore and Kiierr. HairMax is the big guru, having been the first company to patent their devices, test them in published studies, and bring them to the consumer market.
HairMax puts lasers in their cap, comb and band hair growth lights. Kiierr and iRestore use LEDs in theirs. While the effect over time is the same, the lasers do have an advantage.
People often ask if LEDs are as good as lasers. Lasers allow you to have shorter treatment times per session. The hair will not grow faster or stronger because you use lasers, but the time you spend in treatment will be shorter. That is the advantage of lasers over LEDs.
Don’t let anyone tell you LEDs do not work though. They do work; they grow hair as well as any laser. You might find a bargain buying an LED hair growth cap. Compare the treatment time per session in an LED vs. a laser cap.
How Red Light Therapy Regrows Hair
Mitochondria are organelles in the cells. Cytochromes are proteins in the mitochondria. Cytochromes absorb photons of light, kicking off the mitochondria energy cycle.
Dormant follicles grow hair when they absorb red light photons. Cytochrome (photoreceptor) proteins in the scalp’s cells absorb red light photons (energy particles) to stimulate dormant hair follicles. The light absorption kicks off an energy production cycle in the follicle cells.
Human cytochromes are particularly good at absorbing light in the red and infrared ranges. This is why red light therapy is so successful at enhancing so many health processes, and why low level light therapy (LLLT) is so successful as a wellness modality.
Besides stimulating dormant follicles, the new energy fortifies the growing hair. The result is more and stronger hair.
What Science Says about Infrared for Hair Grow
There is some evidence that infrared stimulates hair growth, but there is more evidence for red light success than infrared success.
Researchers combined 665 nm red with 808 nm infrared in a hair “scanner” device. Another group received red light therapy from a 665 nm red light cap without 808 nm infrared. The scanner group receiving red and infrared had better terminal hair density (more hairs) than the red hat group. Unfortunately, this is not an apples to apples comparison.
We do not know if the infrared or the different device type (hat vs scanner) caused the difference in the results. Did the infrared improve the results? On the other hand, was it the use of a scanner rather than a cap that created more hair density?
In a pulsed application, infrared is a hair removal wavelength as seen in this study at pubmed.gov: Comparison of the effects of 665 nm low level diode Laser Hat versus and a combination of 665 nm and 808 nm low level diode Laser Scanner of hair growth in androgenic alopecia. (opens a pubmed.gov study in a new window).
What Science Says about Blue Light for Hair Growth
There is exactly one study testing blue light on hair loss, and it had positive results. In a 2021 Lasers in Medical Science study, twenty patients with androgenetic alopecia (normal hair loss) received two treatments per week for 10 weeks of 417 nm blue light. 90% of the patients had an increase in hair shaft width at 10 weeks. 80% had improvement visible in before and after photos. See the study here: Blue light-emitting diodes in hair regrowth: the first prospective study (opens in a new browser)
If you use blue light at home, wear eye protection. Blue light is harmful to the eyes.
LEDs and Lasers Really Do Grow Hair
Both LEDs and lasers emitting the right energy and wavelengths really do grow hair.
Lasers output light in columns that concentrate on small areas. The energy is strong because it is concentrated. LEDs output light in a more random fashion, so they are “colder” than LEDs.
Researchers using low energy lasers and normal LEDs get the same results. Healing takes place in low energy light as well as high energy light. LEDs with enough energy and the right wavelengths (colors) output photons that are just as useful as laser photons.
After hundreds of studies testing LED light on the body, there is no doubt that LEDs have the same effect as laser light. The healing comes from the photons. So long as there are enough of them of the right wavelength, light stimulates a healing energy creation and nitric oxide response.
How Long Does it Take for Red Light Therapy to Grow Hair?
It takes red light therapy three to six months for you to see visible hair growth results.
Hair grows at about 1/2 inch per month. As in the doctor’s office, only some types of hair loss respond to the therapy. For men, these hair loss types are Norwood Hamilton hair loss types IIa, III, IIIa, III-vertex, IV, IVa and V; and for women, the hair loss types that respond to therapy are Ludwig Savin types I-4, II-1, II-2 and Frontal.
- HairMax says to expect visible hair growth in three or four months
- Kiierr advises that you will see hair growth in four to seven months using their products
- iRestore says that you will see results in three to six months using the iRestore helmet
All results depend on your having a skin and hair type that responds to treatment, and using the products as directed.
Red Light Therapy Does Not Make Hair Grow Faster
Red light therapy does not make hair grow faster. The light energy stimulates dormant follicles so that they start growing hair again. The energy strengthens the existing and the new hair. When new hair does appear, it grows at the normal rate. Hair grows at about 1/2 inch per month whether naturally or through stimulation with red light.
Using infrared to test laser therapy on hair growth, researchers saw new hair appearing in as little as one week from the start of treatment. At-home hair therapy devices usually output red but not infrared light, but the effects of the two energies are often the same in other low level light therapy. See the full study here: Use of the pulsed infrared diode laser (904 nm) in the treatment of alopecia areata (opens in a new browser)
How to Use Red Light Therapy for Hair Growth
To stimulate dormant follicles to grow hair, use a device that outputs one or more of red wavelengths tested in hair growth studies. Hair growth devices designed to cover the scalp give you the best coverage. You can also use a bulb, panel, or handheld red light therapy source.
The key to any red light therapy success is correct dosing. Dosing consists of using the right wavelengths (colors) for the right amount of time to allow the body to absorb a healthy amount of photons.
The right wavelengths are in the range of 635 nm (nanometers) to 655 nm. These are shades of red tested in studies to grow hair. The body responds to ranges of wavelengths, so it makes sense that it responds to more than one wavelength in the follicles. These are just the tested wavelengths. It is possible (and likely) that other wavelengths stimulate dormant follicles as well.
The easiest way to use red light for hair growth is to obtain a hair growth cap, band, or comb and follow the directions to the letter. You have to get the dose right for it to work. Red light therapy for any goal is dose dependent. Too little and too much light are equally useless.
Several vendors sell models shaped for the human head. HairMax is the oldest and best tested of these companies. iRestore and Kiierr are also major brands.
Red Light Therapy for Alopecia Areata
A few studies using red or infrared successfully grew hair in alopecia areata humans and mice, but none of these studies exactly match the treatment you get in an at-home red light therapy device.
In the Super Lizer™ study, the hair grew using the “linear polarized” red and infrared light from a 2200 mW delivery system. That is much more powerful than a home device.
The Journal of Cosmetic Laser Therapy 2006 study delivered 904 nm infrared light. While infrared is certainly a viable red light therapy wavelength, the major hair therapy brands deliver red, not infrared light. Therefore, the study is not apples to apples with at-home treatment.
The 2012 HairMax study grew hair on mice induced to have alopecia areata. This red light study is definitely the closest to the real world. It is just that the study grew hair in mice, not humans.
These are the studies below.
A 2003 study used the Super Lizer™ on fifteen patients with alopecia areata who had patchy hair loss. 46.7% of the treated areas re-grew 1.6 months earlier than untreated counterparts. Super Lizer™ literature claims their product reaches deeper than lasers or LEDs. Therefore, it is not comparable in that regard.
However, Super Lizer™ treats with red and infrared, so this study confirms that red and infrared were associated with hair regrowth in patients with patchy alopecia areata. See the study here: (Linear polarized infrared irradiation using Super Lizer is an effective treatment for multiple-type alopecia areata.
A 2012 study confirmed the safety and efficacy of the HairMax LaserComb in mice with induced alopecia areata (an autoimmune disease). The 655 nm red treated group of six mice had more anagen hair follicles at 6 weeks than the control group of six mice. See the study here: Effects of the Lexington LaserComb on hair regrowth in the C3H/HeJ mouse model of alopecia areata
Using Rogaine with Laser Therapy
You can use Rogaine (Minoxidil) with therapy, but wait an hour after application before starting that day’s laser treatment.
The general rule is not to use hair products before treatment, but it is safe to use Rogaine as long as you wait that one hour.
The reason you do not want product in your hair is to avoid blocking the light from reaching the follicles.
How Often Should You Use Red Light Therapy for Hair Growth?
Most device vendors instruct clients to do treatments every other day. If you are using a device from a hair growth company, follow their instructions to the letter. If you are making it up as you go using a “red light therapy” light without hair growth instructions, use the HairMax protocol.
That is, do treatments every other day such as Monday, Wednesday and Friday. Always leave a day between treatments. Always treat for the time instructed.
In HairMax devices, the treatment time ranges from 90 seconds to 30 minutes. The devices go from very powerful (90 seconds treatment) to average power (30 minutes treatment).
If we had the HairMax irradiance values for their devices, and we knew the target joules per treatment their devices give (the photons absorbed each session), we could calculate a treatment time for a generic device. To copy a protocol with a generic device, we really need to know more data than we have. So we are going to have to wing it.
Since we do not know the HairMax, iRestore or Kiierr joules per treatment or irradiance per device, we can make an educated guess and hope for the best.
Use the advised treatment time the manufacturer gives for a standard session, and do that three days a week. Ensure the light is the same distance from your head at each session.
Whether using a hair growth light or a generic red light therapy device, always use the same distance each session, for the same time per session.
Red light therapy works when the body receives the right amount of joules (photons per area) each session.
Distance from the light dramatically affects how many joules of energy you receive. The time per session dramatically affects how many joules of energy you receive. So keep the distance and time constant!
Best Red Light Therapy Device for Hair Loss
To learn more, go to my article: Does HairMax Really Grow Hair?
The best red light therapy device to grow hair is the HairMax PowerFlex Cap (that is a link to the Hairmax website’s page for the PowerFlex).
It provides hands-free treatment. There’s no cord to tie you to the wall. HairMax gives you six months to try the cap to see if it works for you, otherwise they accept returns and give you a refund.
Can Red Light Therapy Cause Hair Loss?
As far as we know, red light therapy with red or infrared light does not cause hair loss. I have seen anecdotal instances of this question on the web, where there appears to be two situations going on.
First, there is a natural shedding that occurs in cycles, which might look like hair loss. If the hair is dead and shedding, the follicles are making way for new growth. That is normal and not hair loss.
But there is also the case of people who use red light therapy and have visible, measurable hair loss. The question is, were they going to lose that hair anyway? Alternatively, did the light actually cause the loss?
There’s no evidence in the literature for light causing hair loss, but that does not mean we know that.
What we know is that most of the time red and infrared of the right power and schedule will cause hair to grow. The final answer on whether it can also cause hair loss is that we do not know. It doesn’t appear so, but that’s as much an educated guess as anything.
There Is No Scientific Evidence Red Light Reverses Gray Hair
While I have seen anecdotal evidence that red light therapy reverses gray hair, there is no scientific evidence that red light therapy changes hair color.
I have run several pubmed.gov searches but I could not find evidence that any kind of light can change hair color. I think hair color changes do happen under some circumstances, but we do not have the science to make the claim that light changes hair color.
Besides stimulating dormant follicles, the new energy fortifies the growing hair. The result is more and stronger hair.