By Ciobanu Sebastian — Founder & Head of Product, Folliq · Published 9 September 2026 He is not a doctor, dermatologist or trichologist, and does not present himself as one — he reads the primary studies and links them throughout.
If you have spent any time shopping for a red light device for your hair, you have hit this fork in the road. One product says laser. The next says LED. They are aimed at the same problem, they often quote the same wavelength, and the laser one usually costs three or four times more.
The honest answer is not the one either side of the industry wants to give you. Laser sellers will tell you coherence is everything. LED sellers — and we are one of them — have an obvious incentive to tell you it does not matter at all. So this article does something slightly awkward: it lays out the evidence on both sides, including the study that does not flatter LED devices, and tells you where our own product sits in that picture.
What the two words actually mean
Both a laser diode and an LED emit red light. The difference is in how disciplined that light is.
A laser produces light that is coherent (the waves march in step), collimated (the beam stays narrow instead of spreading) and highly monochromatic (almost all the energy sits at one exact wavelength — 655nm, say, with barely any spill).
An LED produces light that is none of those things. The waves are out of step, the light spreads in a wide cone, and the output sits in a band around a centre wavelength rather than on a single point — an LED sold as 660nm typically emits across roughly 640–680nm.
That is the whole physical difference. Everything else — whether one grows more hair than the other — is an empirical question, and it has to be answered with trials, not with physics intuition.
The mechanism does not care about coherence
Low-level light therapy, now more often called photobiomodulation, is thought to work because red and near-infrared light is absorbed by cytochrome c oxidase, an enzyme in the mitochondria of your cells. Absorption there appears to increase cellular energy production and shift signalling in the follicle, which in the scalp is associated with pushing hairs from the resting phase back into the growth phase.
Here is the part that matters for our question: a photon is absorbed by that enzyme, or it is not, based on its wavelength. The enzyme has no way of knowing whether the photon arrived in a coherent beam or a scattered one.
And coherence does not survive the journey anyway. Skin scatters light heavily. A coherent beam loses its coherence within a fraction of a millimetre of tissue, long before it reaches the follicle bulb. This is the point Heiskanen and Hamblin make in their 2018 review in Photochemical & Photobiological Sciences: the early belief that laser properties were essential has not held up. They list the practical advantages of LEDs — no laser safety class to worry about, safe for home use, able to irradiate a large area at once, wearable, and far cheaper per milliwatt — and conclude bluntly that "LED photobiomodulation is here to stay."
So on mechanism, the case for LED is strong. If the article stopped here, it would be a comfortable article for a company that sells an LED device. It should not stop here.
The study that complicates it
In 2021, Lueangarun and colleagues published a systematic review and meta-analysis in the Journal of Clinical and Aesthetic Dermatology that looked specifically at home-use light devices for pattern hair loss, and specifically at how device design affects results. They identified 32 FDA-cleared home-use devices and pooled seven randomised controlled trials.
Overall, the light devices clearly beat sham treatment — a standardised mean difference of about 1.27 in hair density, which is a large effect by the usual conventions. The benefit held for both men and women.
But when the authors split the devices by light source, they found a statistically significant difference (p=0.043):
- Laser-diode-only devices: SMD 1.52
- Devices combining LEDs with laser diodes: SMD 0.85
Read at face value, that favours laser. It would be dishonest of us to leave it out, so there it is.
It would also be sloppy to read it at face value, for three reasons.
First, the comparison is confounded by shape. In the same analysis, comb-type devices scored 1.53 and helmet-type devices scored 0.97. Combs in these trials were predominantly laser; helmets predominantly LED or mixed. A comb parts the hair as it moves, putting the emitters against the scalp. A helmet sits on top of the hair. That is a difference in how much light actually reaches the skin, not a difference between coherent and incoherent photons — and the two variables are almost perfectly tangled in this dataset.
Second, the LED arm was not LED. The comparison was laser-only versus LED plus laser combined, not laser-only versus LED-only. It is a comparison of two device categories, not of two light sources.
Third, seven trials is not many. These were separate studies with different populations, different session lengths, different total treatment durations (16 to 26 weeks) and different doses. Subgroup analyses on a pool that size are hypothesis-generating. They are not a verdict.
The fair summary: home-use light therapy has decent evidence behind it as a category, and within that category we do not yet have a clean head-to-head trial of laser versus LED at matched wavelength, matched dose and matched scalp contact. Anyone who tells you the question is settled — in either direction — is telling you more than the literature supports.
The variables that are actually doing the work
If you stop arguing about the emitter and look at what the trials had in common, three things matter more than the laser/LED label.
1. Wavelength
The trials cluster in a narrow band, roughly 620 to 678nm, which is where cytochrome c oxidase absorbs efficiently. A device at 630nm and a device at 660nm are both inside the useful window. A device selling you deep red aesthetics at 750nm, or a warm-looking bulb with no wavelength published at all, is not.
2. Light actually reaching the scalp
This is the most underrated variable in the entire category, and it is the one the comb-versus-helmet split is quietly pointing at. Hair is very good at blocking light. A device that sits on top of your hair is treating your hair. A device that gets emitters — or light-guide bristles — down to the skin is treating your scalp, which is where the follicle is. If you take one practical thing from this article, take that one.
3. Dose, which is not "more is better"
Photobiomodulation follows a biphasic dose response, documented by Huang, Hamblin and colleagues. Too little light does nothing. The right amount stimulates. Past a certain point the effect flattens and then reverses, so a higher dose can produce less benefit than a moderate one. This is genuinely counterintuitive and it is why doubling your session time is not a shortcut.
Where that optimum sits for the scalp is not firmly established. The Lueangarun review cites roughly 2 to 4 J/cm² as a reasonable therapeutic range, drawing on Hamblin's work. Other published protocols for hair sit higher. The range quoted in the literature is wide enough that we will not pretend to a precision nobody has.
Where the Folliq device sits, plainly
The Folliq Red Light Scalp Massager is an LED device, not a laser device. It uses 24 red LEDs at 660nm, plus 8 blue LEDs at 460nm for sebum, feeding 56 light-guide bristles designed to carry light past the hair and onto the scalp.
Three things we will not claim:
- It has not been through a clinical trial. The research discussed above studied the technology, run independently, on other manufacturers' devices. None of it is a study of ours.
- 660nm is not 655nm. The two best-known trials in this area (Lanzafame 2014, Jimenez 2014) used 655nm laser devices. Adjacent is not identical, and we say so.
- It is a cosmetic device. Not a medical device, not FDA-cleared, not a treatment for any condition.
What we do think is defensible: the mechanism does not require coherence, LED sits comfortably inside the wavelength window the trials used, and the bristle design targets the variable — light reaching the scalp — that the evidence suggests actually separates devices that work from devices that do not.
So which should you buy?
If you want the option with the largest body of trial evidence attached to that specific form factor, and the budget is not a constraint, an FDA-cleared laser comb has the deepest paper trail. That is a real answer and we are not going to talk you out of it.
If you are choosing between LED devices — or between an LED device and nothing, which is the more common situation — the questions worth asking are these:
- Is the wavelength published, and is it between about 620 and 680nm?
- Does the design get light to the skin, or does it sit on the hair?
- Is the session length fixed, so you cannot accidentally overshoot the dose?
- Is the seller telling you what the device does not do?
And whichever you choose: consistency beats intensity. The trials that showed results ran 16 to 26 weeks. Nothing in this category rewards a fortnight of enthusiasm.
References
- Heiskanen V, Hamblin MR. Photobiomodulation: lasers vs. light emitting diodes? Photochem Photobiol Sci. 2018;17(8):1003–1017. PMID 30044464.
- Lueangarun S, et al. A Systematic Review and Meta-analysis of Randomized Controlled Trials of United States Food and Drug Administration-Approved, Home-use, Low-Level Light/Laser Therapy Devices for Pattern Hair Loss: Device Design and Technology. J Clin Aesthet Dermatol. 2021;14(11):E64–E75. PMID 34980962.
- Huang YY, Chen AC, Carroll JD, Hamblin MR. Biphasic dose response in low level light therapy. Dose Response. 2009;7(4):358–383. PMID 20011653.
- Lanzafame RJ, et al. 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. PMID 25124964.
- Jimenez JJ, et al. 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. PMID 24474647.
This article is for general information. Folliq products are cosmetic scalp-care products. They are not intended to diagnose, treat, cure or prevent any disease. If your hair loss is sudden, patchy or accompanied by other symptoms, see a doctor rather than a device.