Red light therapy before and after: what the trials saw, and when

A before-and-after is the one piece of evidence everyone looks at and almost nobody can check. It answers the right question, “what will I see?”, with the weakest kind of proof: two photos, chosen by someone who wants you to buy. This page answers the same question from the trials instead, area by area, and then shows how to take your own photos so the comparison means something.

Realistic results, area by area

Face: fine lines and texture

The trial behind most skin claims is Wunsch and Matuschka (Photomedicine and Laser Surgery, 2014). They assigned 113 of 136 volunteers to four groups given twice-weekly polychromatic light, about 9 J/cm² in the 611 to 650 nm range, for 30 sessions, and compared them with 23 controls. Blinded raters scored photos, and skin roughness and ultrasound collagen density were measured; all improved, and broadband light added nothing over red alone.

So the honest “after” for the face is about 15 weeks of regular sessions, judged by people who did not know who had been treated, with a modest change. The abstract describes no sham device, and one trial is one trial. That is why we stop at moderate, and why a dramatic four-week face photo should make you suspicious rather than excited.

Hair

Hair is where the “after” has the most numbers behind it, and the longest wait. In Lanzafame and colleagues’ 2013 trial of a 655 nm helmet used every other day for 16 weeks, the hair count in a marked patch of scalp rose by 67 in 44 men with active devices against 32 with a sham; in their 2014 trial in 47 women, 100 against 24. In four sham-controlled laser-comb trials (Jimenez and colleagues, 2014), terminal hair density rose by 18.4 to 25.7 hairs per cm² over 26 weeks, against 1.6 to 9.4 with a sham.

Sixteen weeks is the minimum before a hair photo means anything, and the change is in density, which photographs badly under different light. Our hair loss guide covers the weaker side of the evidence too.

Acne

Acne before-and-afters are the most persuasive and the least supported. The 2016 Cochrane review (Barbaric and colleagues), 71 trials and 4,211 participants, could not pool most comparisons and rated the evidence on people’s own assessment of improvement very low. Acne also comes and goes on its own over weeks, so any two photos a month apart can show a change. Blue light carries more of the acne case than red; red vs blue light sets them side by side.

Belly fat and weight loss

“Red light therapy weight loss before and after” is a popular search with almost nothing behind it. The FDA has cleared some low-level laser devices for non-invasive body contouring at treated sites, which is a temporary change in measured circumference, not weight lost. A 2013 review in Lasers in Surgery and Medicine concluded that studies of it as a stand-alone procedure were inadequate. A stomach photo changes with what you ate, how you stand and whether you breathe out; none of that is the light.

Why most before-and-after photos mislead

Nearly every before-and-after you will see was chosen by someone selling the device, and it can be honest and still not tell you much. The common ways two photos exaggerate a change:

• Light. Overhead light deepens every line and shadow; soft front light from a window flattens them. Swapping one for the other erases wrinkles without a single session.
• Angle and distance. A camera a few inches lower, or closer, changes the jaw, the neck and the apparent size of everything.
• Expression and hydration. A slight smile, a morning puffy face against an evening one, or moisturiser applied before the second photo all show up as “results”.
• The camera. Phone cameras smooth skin by default, differently in different light, and some apply beauty filters unless you turn them off.
• Selection. The best result out of hundreds of users, shown as if it were the usual one.

US advertising rules address the last one directly. The FTC’s Endorsement Guides say that when an advertiser shows a consumer’s results, it must have evidence those results are what people generally get, or disclose clearly what they generally get. When a brand’s before-and-after page has no such statement, the photos are the best case, not the typical one.

How to take your own before and after photos

Your own photos are the only before-and-after you can trust, if you take them the same way every time. This takes five minutes once a month.

1. Fix the light. Face a window on an overcast day, or one lamp in the same spot every time. No overhead light, no flash.
2. Fix the camera. Phone at eye level, at arm’s length or on a stand, the rear camera, beauty mode and filters off, the same zoom.
3. Fix yourself. Clean, dry skin, no makeup, hair back, a neutral face with relaxed eyes. Same time of day each time, since faces are puffier in the morning.
4. Take three angles. Front, left and right, plus a close-up of the area you care about. For hair, the same parting, dry, from directly above.
5. Before the first session, then every four weeks. Do not compare until week 8 at the earliest, week 12 for skin and week 16 for hair.
6. Compare them side by side at the same size, ideally with someone else guessing which is which. If they cannot tell, neither can you.

What the makers say you will see, and when

These are the device makers’ own timelines, from their sites and Amazon listings on 1 November 2026, for comparison with the trials above. None comes from an independent study.

The skin timelines are shorter than the trial above, and the hair one matches. Read the four-week claims as the earliest anyone might notice anything, not as when the change is finished.

Devices to run your own before and after

If you are going to photograph a change, use a device that states enough to repeat the dose. Each of these is covered in full in our mask comparison.

What we have not measured

We have no before-and-after photos and have run no trial. The results above come from the published trials we cite, read from their abstracts, and the timelines from the makers’ sites and Amazon listings on 1 November 2026.

What we would run, and what would make this page worth more than any brand’s gallery: twelve volunteers, half with an active mask and half with a sham that glows the same colour without the LEDs that matter, photographed under fixed studio light every four weeks for 16 weeks, with the photos scored by raters who do not know which group is which, alongside a skin roughness reading. Small, and n=12 is a limitation we would state on the result. It is still more than most before-and-after pages are built on.