Hair Loss Sucks. How Red Light Therapy Can Help (the Science)

Hair loss is depressing. What therapy works well and has no side effects?

Red light therapy restores hair growth in dormant follicles. The process works as well as minoxidil, the FDA-approved topical treatment. Unlike minoxidil or FDA-approved finasteride, red light therapy has no long-term or short-term side effects.

To date, the FDA has approved sports caps, headbands, laser combs and helmets for hair regrowth at home, without a prescription.

How Red Light Therapy Grows Hair

The precise mechanism for red light therapy’s effect on hair growth is not yet known, but there are several strong theories.

Improved Blood Flow

Red light therapy stimulates blood flow, which might have some part in its ability to trigger hair growth.

Researchers theorize that improved blood flow is how Minoxidil helps dormant follicles to grow hair again.

Red light therapy opens blood vessels by dislocating nitric oxide from the mitochondria to the blood vessels. There are thousands of mitochondria in every cell. They house the factories where biological energy is produced.

When the photons absorb in the mitochondria, they knock loose nitric oxide into the arteries. Nitric oxide triggers dilation, making the blood vessels larger. More blood, oxygen, and nutrition reach the hair follicles.

The theory is that the hair follicles benefit from the blood, oxygen, and nutrition supply.

Improved Adenosine Triphosphate Output

The nitric oxide that the photons knocked loose had been inhibiting cellular energy production. With that nitric oxide out of the way, the mitochondria make more adenosine triphosphate (ATP).

In our trillions of cells, we have quadrillions of mitochondria making ATP cellular energy.

ATP molecules act as batteries, powering every biological function.

The theory is that red light therapy gives hair follicles the energy required to make hair.

Growth Factor Stimulation

Red light therapy enhances the production of growth factors. These proteins stimulate cell replication as part of the healing process.

One study found that red light therapy heals wounds faster because it promotes platelet-derived growth factor (PDGF) and transforming growth factor (TGF)-²[1].

There are multiple growth factors involved in the hair-growing process[2].

Part of red light therapy’s effect on hair growth might be due to its ability to stimulate more growth factor activity on the scalp.

[1] Keskiner I, Lutfioğlu M, Aydogdu A, Saygun NI, Serdar MA. Effect of Photobiomodulation on Transforming Growth Factor-β1, Platelet-Derived Growth Factor-BB, and Interleukin-8 Release in Palatal Wounds After Free Gingival Graft Harvesting: A Randomized Clinical Study. Photomed Laser Surg. 2016 Jun;34(6):263-71. doi: 10.1089/pho.2016.4094. Epub 2016 Apr 18. Erratum in: Photomed Laser Surg. 2018 Jan;36(1):58. PMID: 27088277; PMCID: PMC4892223.

[2] Lin WH, Xiang LJ, Shi HX, Zhang J, Jiang LP, Cai PT, Lin ZL, Lin BB, Huang Y, Zhang HL, Fu XB, Guo DJ, Li XK, Wang XJ, Xiao J. Fibroblast growth factors stimulate hair growth through β-catenin and Shh expression in C57BL/6 mice. Biomed Res Int. 2015;2015:730139. doi: 10.1155/2015/730139. Epub 2015 Jan 1. PMID: 25685806; PMCID: PMC4313060.

Scientifically and FDA-Validated Hair Growth Light Therapy Options

A 2021 study published in The Journal of Clinical and Aesthetic Dermatology listed the FDA-approved options that also had published science to back their use.

The authors found seven double-blinded, randomized, and placebo-controlled trials testing FDA-approved devices on hair growth.

These included studies on twenty sports caps, two headbands, four combs, and six helmets.

The study authors found that all devices worked equally well to increase hair density compared to controls.

LEDs were as effective as lasers at growing hair.

Men and women grew hair equally well on average when using comb or helmet hair growth devices.

The authors of the meta-analysis determined that the devices (listed below) worked equally well for men and women.

Below are the LED and laser configurations of the devices that successfully grew hair in the studies.

How Well These Devices Worked

Hair density is the amount of hair per square centimeter. The studies show that these devices significantly improved hair density in subjects’ heads.

This analysis included improvement details only for four of the devices. I’m not sure why so much data is missing.

Below are the improvements as stated in the meta analysis. If the hair density result is missing here, that’s because it’s missing in the original meta analysis.

Still, the results that are included are interesting, as they significantly improved hair density.

How Often These Devices Were Used for Hair Growth

The reported studies used the devices according to manufacturer directions. If you are shopping for red light therapy, this section should be helpful.

Normally you see a relationship between power and time. Powerful devices have shorter session lengths.

The relationship between power and time breaks down with these FDA-approved hair growth devices.

Most devices come with instructions for 20 or 30 minutes of use per session. A few require much less time, despite not being more powerful.

I asked HairMax about the disconnect. Why didn’t devices with more light have shorter treatment times? I would think that light with 272 diodes would offer a faster treatment time than one with 148 diodes.

The answer didn’t help much, it was a form of “it depends on how much hair you want to grow,” or maybe she said, “how fast you want to grow your hair.” The conversation was quite a while ago.

If you are including time management in your shopping criteria, pay attention to the schedules below. The HairMax and Nutrastim combs and the HairMax headbands have remarkably short treatment times.

How Long Red Light Therapy Takes to Grow Hair, According to Science

Red light therapy starts growing hair in as little as five weeks, but a 6-month schedule is much more realistic.

Red Light Therapy Grows Hair in as Little as 4 Weeks

Most studies report a period of 30 to 50 weeks to grow hair using red light.

Two studies report growing hair much faster.

A study published in Photobiomodulation, Photomedicine and Laser Surgery reports that red light therapy grew hair in only 5 weeks.

The researchers tested the effect of red light on 25 men with androgenetic alopecia. The subjects were 25 to 40 years old.

The men received red light therapy twice a week for ten weeks.

At different points in the study, the authors photographed the men’s hair. They gave the photographs evaluators to record hair density. The evaluators did not participate in the therapy phase so as not to bias their tallies.

The hair density increased a significant amount at week 5 of the study. The hair density continued to increase through the 20th and final week of therapy. The hair density stopped increasing when therapy stopped.

A study published in Lasers in Medical Science reports that light therapy grew hair in only 4 weeks[3].

This research tested the effect of 417 nm blue light on hair growth.

Twenty-eight subjects with androgenetic alopecia received blue light treatment two times per week, for ten weeks.

After only 1 month, the hair density and shaft thickness increased in 90% of the subjects.

There were no adverse events. Weirdly, some subjects had darker hair after therapy.

The authors concluded, “Light therapy is a promising therapy for patients affected by androgenetic alopecia and other diseases characterized by hair loss.”

This research tested the effect of 417 nm blue light on hair growth.

Twenty-eight subjects with androgenetic alopecia received blue light treatment two times per week, for ten weeks.

After only 1 month the hair density and shaft thickness increased in 90% of the subjects.

There were no adverse events. Weirdly, some subjects had darker hair after therapy.

The authors concluded that “light therapy is a promising therapy for patients affected by androgenetic alopecia and other diseases characterized by hair loss.”

[3] Lodi G, Sannino M, Cannarozzo G, Giudice A, Del Duca E, Tamburi F, Bennardo L, Nisticò SP. Blue light-emitting diodes in hair regrowth: the first prospective study. Lasers Med Sci. 2021 Oct;36(8):1719-1723. doi: 10.1007/s10103-021-03327-9. Epub 2021 Jun 8. PMID: 34101089.

Red Light Therapy Grows Hair in 38-40 Weeks

Red light therapy grows hair in 38 to 40 weeks, according to a study published in the Journal of Cutaneous and Aesthetic Surgery in 2021.

This study tested the effectiveness of an FDA-approved therapy helmet. Subjects were between 18 and 40 years old and had mild, moderate, and severe androgenetic alopecia.

The subjects’ ages ranged from 18 to 40 years old. They had moderate to severe androgenetic alopecia.

The therapy grew hair for 80% of the 1,383 subjects, with significant results at 38 to 40 weeks.

The authors concluded that those with mild androgenetic alopecia should use the helmet at least 133 times over 38 weeks.

Those with moderate to severe androgenetic alopecia should use the helmet at least 142 times over 40 weeks.

Women had good results, but the men’s results were better. Weirdly, those subjects who had dandruff, itchiness or a rash before treatment started had better results.

What Kind of Red Light Therapy Grows Hair?

Red, infrared, blue, and ultraviolet lights stimulate hair growth. The science concentrates on red light, so we have the most evidence supporting its use.

Many Wavelengths Grow Hair

In a 2022 meta-analysis published in Dermatology Surgery, authors reported on 36 published studies that tested red light therapy on 966 subjects.

They concluded that:

• ultraviolet and infrared light grow hair on people with alopecia areata
• red and infrared light grow hair on people with androgenetic alopecia

They did not report on red light for alopecia areata, or on ultraviolet for androgenetic alopecia.

Please be aware that ultraviolet can be harmful and is supported by only a small amount of evidence.

Red Light Grows Mouse Hair

Alopecia areata is an autoimmune disease. The lymph system produces T-cells in and around the hair follicles.

A 2012 study published in Lasers in Medicine & Science supports using red light to grow hair[4], based on its success in growing hair on mice.

Researchers studied the effects of the HairMax LaserComb on mice with non-scarring alopecia.

In this randomized, placebo-controlled study, mice received 655 nm red light for 6 weeks.

Treatment times were just 20 seconds long.

The sham group received the same treatment but with a device that did not emit the therapeutic light.

All the mice in the treatment group had significantly more hair per square centimeter (i.e., the hair density), and significantly thicker hair shafts. The sham group had no changes.

[4] Wikramanayake TC, Rodriguez R, Choudhary S, Mauro LM, Nouri K, Schachner LA, Jimenez JJ. Effects of the Lexington LaserComb on hair regrowth in the C3H/HeJ mouse model of alopecia areata. Lasers Med Sci. 2012 Mar;27(2):431-6. doi: 10.1007/s10103-011-0953-7. Epub 2011 Jul 9. PMID: 21739260.

Red Light Grows Hair on Men with Androgenetic Alopecia

In a study published in the journal Photobiomodulation, Photomedicine and Laser Surgery, the authors tested the effect of red light on 25 men with androgenetic alopecia.

The men’s ages ranged between 20 and 54 years old. They received red light therapy twice a week for ten weeks.

At different points in the study, the authors photographed the men’s hair. They gave the photographs to “blinded” evaluators to record hair density. The evaluators did not participate in the therapy phase so as not to bias their tallies.

The men’s hair density had a significant increase starting at week 5 of the study. The hair density continued to increase through the 20th and final week of therapy. The hair density stopped increasing when therapy stopped.

Red Light Grows Hair on Men and Women with Androgenetic Alopecia

In a 2021 meta analysis published in the Journal of Cutaneous and Aesthetic Surgery in 2021[5], researchers reported that red light grows hair on men and women with androgenetic alopecia.

The authors gathered the 15 largest randomized controlled studies of red light therapy for hair growth. They consolidated the results to see what conclusions they could draw.

The authors concluded that red light therapy is a safe, non-invasive and effective treatment for androgenetic alopecia for both men and women.

[5] Pillai JK, Mysore V. Role of Low-Level Light Therapy (LLLT) in Androgenetic Alopecia. J Cutan Aesthet Surg. 2021 Oct-Dec;14(4):385-391. doi: 10.4103/JCAS.JCAS_218_20. PMID: 35283601; PMCID: PMC8906269.

Conclusion

Red light therapy is a non-invasive, safe, and effective hair growth treatment available without a prescription for at-home use.

FDA-approved devices include headbands, helmets, sports caps, and combs.

Most devices require 20 to 30 minutes, but a few have very short treatment session times.

How to Buy Red Light Therapy for Hair Growth

Here are the devices mentioned in this article, below.

If you’re ready to buy a hair growth cap, don’t do anything until you read our article about HairMax: Does HairMax Really Work? 13 Studies Say “YES”