Red light therapy: caps, helmets and combs
Red light at home: what the trials show, how often you use it, and what to look for before you buy a device.
What red light therapy is
"Red light therapy" is the name you will see in shops and on social media. Researchers call it low-level laser therapy, or low-level light therapy. It uses red light from small lasers or LEDs at low power. It does not heat or burn the skin, and it is not the kind of laser used for hair removal. Most home devices for hair come as a cap or helmet that you wear, or as a comb that you move across your scalp.
The devices tested on hair used red light at a wavelength of about 655 nanometres.3,4 Large red light panels and face masks sold for skin are a different kind of product. They have not been tested on hair loss in the same way, and they may not deliver the same dose to the scalp.
The idea is that the light acts on hair follicles, the small organs in the skin that make each hair. The leading theory is that cells in the follicle absorb the light and use it to make more energy, which may help follicles stay in, or return to, their growing phase. This has not been proven, and how light therapy works on hair is not fully understood.
What it does not do is change hormones. Pattern hair loss is driven by the hormone DHT, which slowly shrinks sensitive follicles. Light therapy does not touch DHT, and it works in a different way from minoxidil or finasteride, so it can be used alongside them.
What the trials show
The best evidence comes from trials that compared a real device with a sham device. A sham device looks and feels the same, but does not give the treatment light. Neither the users nor the researchers knew who had which. That makes it less likely that hope or expectation explain the results.
Laser combs. A set of trials tested combs in men and women with pattern hair loss for 26 weeks.1 Women using an active comb gained about 20 thick, pigmented (terminal) hairs per square centimetre, against about 3 with a sham comb. Men gained between about 18 and 26 such hairs per square centimetre, against about 2 to 9 with a sham. The effect did not depend on age, sex or the model of comb. An earlier trial of a comb in men pointed the same way.3
Laser helmets. Smaller trials tested a helmet for 16 weeks. Men using the real helmet had 39% more hair growth than men using a placebo helmet.4 In women, the difference was 37%.5
A 2017 analysis that pooled trials also found light therapy better than placebo in men, although the studies differed a lot from each other.6
The trials also have limits, and you should know them:
- They were short, from about four to six months. We do not know how results hold up over years.
- Most were small.
- They compared devices with sham devices, not with minoxidil or finasteride, so they cannot tell you which works better.
- In women, a Cochrane review rated the evidence for laser combs as low quality. Women's own ratings of improvement were not clearly better than with a sham comb.7
None of the trials reported serious side effects.1,4,5
Where it fits
The 2017 European guideline on pattern hair loss suggests light therapy as an add-on to other treatment, for both men and women.2 "Suggest" is one step below its strongest advice, which it gives to minoxidil and, for men, finasteride. The guideline also limits its support to devices with energy levels that worked in trials.
The guideline makes no recommendation for use longer than six months.2 In plain words: light therapy has some short-term evidence, but less than the main medicines, and very little beyond six months.
How you use it
Each device comes with its own schedule: how many minutes per session, and how many sessions a week. In the trials, people used their devices several times a week, every week, for months.1,4 Follow the instructions for your device rather than a schedule from another one.
A few general points:
- Keep to the schedule. Like other hair treatments, any effect builds slowly. Regular sessions matter more than long ones, and using a device more often than the instructions say has not been shown to help.
- Reach the scalp. Light needs to reach the skin, not just the hair. Combs part the hair as you move them; caps need to sit close to the head.
- Protect your eyes. Do not look into the light, and follow any eye-safety advice in the instructions.
Plan to judge the result at about six months, the same point the guideline uses for the main medicines.2 Take photos of the same areas, in the same light, before you start, and compare them then.
If it is helping at six months, you may decide to continue. Just know that there is little trial evidence beyond that point, and we do not know how long any gain lasts after you stop.
Caps, helmets or combs
They all use the same kind of light. The difference is mostly in how you use them.
| Cap or helmet | Comb | |
|---|---|---|
| How you use it | Wear it, hands free | Move it slowly by hand |
| Coverage | Top of the head at once | One section at a time |
| Effort | Easy to do while resting | Needs attention each session |
| Trials | Helmet: 16 weeks | Comb: 26 weeks |
A cap suits you if you want something you can wear while you read or rest, and if keeping to a schedule is your main worry. A comb asks more of you each session, but it parts the hair as it moves, which can help light reach the scalp. Caps usually cost more. Whichever you choose, the best device is the one you will actually use, week after week.
Who it may suit
Light therapy may suit you if:
- you already use minoxidil or finasteride, and want to add something
- you cannot use or do not want to use minoxidil or finasteride, and you accept that light therapy on its own has less support
- your hair is thinning, rather than gone from smooth, bald areas
It is not a replacement for a diagnosis. If you do not know why your hair is thinning, see a doctor first. You can read about the two main medicines in our minoxidil guide and our finasteride guide.
Before you buy one
Home devices are not cheap, and claims in this market vary a lot. Before you pay, check the device against this list:
- A published trial. Has this device, or one very like it, been tested against a sham device in a published trial? Ask for the reference, and check it on PubMed.
- Light output that matches the trials. The guideline supports only devices with energy levels shown to work in trials.2 The seller should state the device's light output and explain how it compares.
- A clear schedule. You should know before you buy how many minutes each session takes, how many sessions a week, and for how many months.
- Honest claims. Expect slow, modest change, judged at about six months. Be wary of promises such as "regrow your hair in 30 days", "works for everyone" or "a cure for baldness".
- A fair return policy. Read the return terms and the warranty before you pay, and keep them in writing.
If FOLIQ ever sells light devices, they will have to meet this checklist, and this guide will not change to suit them.
For a practical routine, see using a red light device.
Sources
Numbered in the order the guide first cites them.
- 1
In four sham-controlled trials, laser combs added about 18 to 26 terminal hairs/cm² in men and about 20 in women over 26 weeks, against about 2 to 9 with sham devices.
Jimenez JJ, Wikramanayake TC, Bergfeld W, et al. (2014). Efficacy and safety of a low-level laser device in the treatment of male and female pattern hair loss: a multicenter, randomized, sham device-controlled, double-blind study. Am J Clin Dermatol 2014;15(2):115–127
- 2
The 2017 European guideline recommends topical minoxidil for women and men and finasteride 1 mg for men, suggests low-level laser as an add-on, makes no recommendation on PRP, and advises judging results at 6 months. Its own expiry date was June 2020, and we found no newer version.
Kanti V, Messenger A, Dobos G, et al. (2017). S3 – European Dermatology Forum Guideline for the Treatment of Androgenetic Alopecia in Women and in Men. European Dermatology Forum, S3 guideline (literature to Oct 2015, expiry 06/2020)
- 3
In a 26-week sham-controlled trial in 110 men, a laser comb increased terminal hair density more than a sham device, with no serious side effects.
Leavitt M, Charles G, Heyman E, et al. (2009). HairMax LaserComb laser phototherapy device in the treatment of male androgenetic alopecia: A randomized, double-blind, sham device-controlled, multicentre trial. Clin Drug Investig 2009;29(5):283–292
- 4
In 41 men, a red-light laser helmet used every other day for 16 weeks gave 39% more hair growth than a placebo helmet, with no side effects reported.
Lanzafame RJ, Blanche RR, Bodian AB, et al. (2013). The growth of human scalp hair mediated by visible red light laser and LED sources in males. Lasers Surg Med 2013;45(8):487–495
- 5
In 42 women, the same red-light helmet gave 37% more hair growth than a sham device over 16 weeks, with no side effects reported.
Lanzafame RJ, Blanche RR, Chiacchierini RP, et al. (2014). The growth of human scalp hair in females using visible red light laser and LED sources. Lasers Surg Med 2014;46(8):601–607
- 6
Pooled trials found that minoxidil (in men and women), finasteride 1 mg and low-level laser all worked better than placebo, although the studies varied a lot.
Adil A, Godwin M (2017). The effectiveness of treatments for androgenetic alopecia: A systematic review and meta-analysis. J Am Acad Dermatol 2017;77(1):136–141.e5
DOI 10.1016/j.jaad.2017.02.054PubMed 28396101
Partly checked: we could read the record but not every number.
- 7
Across trials in women, minoxidil nearly doubled the chance of moderate or marked regrowth compared with placebo, 2% and 5% did about the same, and finasteride 1 mg did no better than placebo.
van Zuuren EJ, Fedorowicz Z, Schoones J (2016). Interventions for female pattern hair loss. Cochrane Database Syst Rev 2016;(5):CD007628
What changed
- Last updated
- November 10, 2026
- Next review
- May 10, 2027
First published. No changes since.