Key takeaways
- Cleveland Clinic calls red light therapy an emerging treatment; more clinical trials are needed to confirm it works.
- A 2014 controlled trial found red light improved skin complexion, roughness and collagen density vs controls.
- The acne reviews are divided, and hair growth evidence is positive in men with high heterogeneity.
- Cleveland Clinic finds no scientific evidence for weight loss, cancer, cellulite removal or depression/SAD.
- Devices are 510(k)-cleared for specific indications, not FDA-approved.
What do the studies on red light therapy show?
Red light therapy — also called low-level light therapy, low-level laser therapy or photobiomodulation — uses low levels of red light and is promoted for wrinkles, scars, redness and acne.
Cleveland Clinic calls it an emerging treatment and says more clinical trials are needed to confirm its effectiveness.
The proposed mechanism is still a proposal.
Red light therapy is thought to act on the mitochondria inside cells, with proposed effects including stimulated collagen and fibroblast production, better circulation and less inflammation.
Cleveland Clinic describes this only as how red light therapy is thought to work: these are proposed mechanisms, not proven outcomes.
Cleveland Clinic also cautions that many published red light studies included only a small number of people, lacked a placebo group, or were conducted in animals or cells rather than humans.
So the verdict on this page rests on the studies that measured outcomes in people:
- A 2014 controlled trial of 136 volunteers that compared 30 twice-weekly sessions of red light or broadband light with controls (Wunsch and Matuschka).
- A 2018 systematic review of 31 randomized trials of LED devices in dermatology (Jagdeo et al.).
- The 2016 Cochrane review of light therapies for acne — 71 trials, 4,211 participants.
- A 2017 meta-analysis of randomized trials of low-level laser therapy for hair growth (Adil and Godwin, Journal of the American Academy of Dermatology).
- The 2019 MASCC/ISOO international guideline on photobiomodulation for mouth sores during cancer treatment (Zadik et al.).
Where does red light therapy work?
Skin complexion and collagen — one controlled trial. In the 2014 trial, 30 twice-weekly sessions of red light (611–650 nm) improved skin complexion and roughness and raised ultrasound-measured collagen density compared with controls, and broadband light showed no advantage over red light alone.
It is one trial with one device's parameters — measured in people, but not a promise for any device, course or person.
The skin-specific evidence, from this trial to the cleared wrinkle and acne device categories, is the subject of our red light therapy for skin guide.
Acne — two reviews, and they are divided. A 2018 systematic review of 31 randomized trials of LED devices in dermatology gave its grade B recommendation to acne, herpes simplex and zoster, and acute wound healing — and only grade C or D to other skin conditions — while flagging small samples, missing blinding or sham controls and varied light parameters.
The 2016 Cochrane review of light therapies for acne, covering 71 trials and 4,211 participants, rated the evidence on patients' global improvement as very low quality and concluded that high-quality evidence is lacking.
Read together, the reviews say something may be there for acne, and neither treats it as settled.
Hair growth — positive, in men, with caveats. A 2017 meta-analysis of randomized trials found low-level laser light therapy superior to placebo for hair growth in men with androgenetic alopecia, while flagging high heterogeneity, meaning the trials' results varied widely.
Its finding covers men; we found no equivalent meta-analysis for women in the sources we checked.
The per-benefit grading, including pain uses, is on our benefits page.
Mouth sores during cancer treatment — one of the best-supported medical uses, and not a med spa service. The MASCC/ISOO international guidelines recommend specific photobiomodulation protocols to prevent oral mucositis in certain cancer patients, including stem-cell transplant and head-and-neck radiotherapy patients.
That is a medical protocol delivered in cancer care, not a treatment on a spa menu.
One distinction keeps all of this honest: these are study findings, not blanket endorsements of the devices.
Light-based devices are Class II devices cleared through the FDA's 510(k) process, with cleared categories covering over-the-counter wrinkle reduction, over-the-counter red and blue light devices for mild-to-moderate acne, laser combs for male androgenetic alopecia and non-thermal lasers for adjunctive pain therapy.
A clearance covers only the indication in that device's own 510(k) submission, not every use marketed for the device.
FDA-cleared light device categories (Class II, 510(k))
| Product code | Cleared category |
|---|---|
| OHS | Over-the-counter light-based wrinkle reduction |
| OLP | Over-the-counter red and blue light for mild-to-moderate acne |
| OAP | Laser combs for male androgenetic alopecia |
| NHN | Non-thermal lasers for adjunctive pain therapy |
Where does red light therapy not work?
The clearest line in this research divides the promoted claims from the evidence.
Cleveland Clinic states there is no scientific evidence supporting red light therapy for weight loss, cancer, cellulite removal, or mental health conditions such as depression and seasonal affective disorder.
Some human evidence
- Skin complexion and collagen (one controlled trial)
- Acne (two reviews, divided)
- Hair growth in men (meta-analysis, with caveats)
- Mouth sores in cancer care (not a med spa service)
No scientific evidence, per Cleveland Clinic
- Weight loss
- Cellulite removal
- Cancer
- Depression and seasonal affective disorder
So be careful with the marketing pitch.
If a provider or product page sells a red light bed or pod on fat loss, cellulite reduction or "detox," the claim sits beyond what the reviewed evidence supports — and we found no support for "detox" claims in the sources we checked either.
Paying for those results means paying ahead of the data.
To be precise about what that means: "no scientific evidence" is Cleveland Clinic's finding about the published research, not a guarantee the treatments do nothing.
But no source we checked shows red light therapy works for those outcomes, and that is not a foundation for spending money on them.
Find red light therapy providers near you
Compare Google ratings, reviews and posted prices at med spas in your city.
How long does red light therapy take to work?
Red light therapy is a course, not an event.
Cleveland Clinic says it usually needs ongoing sessions — one to three a week, for weeks or even months — and that health insurance typically does not cover it, so the commitment comes before any result.
How quickly a visible change arrives is not something the sources settle.
We found no primary source giving a standard time-to-results for red light skin treatment.
The clearest anchor is the 2014 trial above, which measured its outcomes after 30 twice-weekly sessions — 15 weeks on that schedule, by simple arithmetic rather than any figure the trial states.
That is one trial's measurement point, not a promise for any device, course or person.
How to find a red light therapy provider
The evidence grades so differently from claim to claim that the questions you ask matter more than the name on the menu.
Make these the questions before you book.
- Which device, exactly — brand or model — and which FDA clearance does it hold, and for which indication? A 510(k) clearance belongs to one device and one indication.
- How many sessions, at what weekly cadence, does the provider recommend — and what result is the course meant to produce?
- What is the total cost of the full course, in writing? Health insurance typically does not cover red light therapy, per Cleveland Clinic.
- Is eye protection provided at every session?
- If the pitch is weight loss, cellulite or "detox": which study shows it? Cleveland Clinic states there is no scientific evidence supporting red light therapy for weight loss, cancer, cellulite removal or depression/SAD.
At-home devices raise the same questions with less supervision.
Cleveland Clinic says they are generally safe but may be less powerful than the devices used in a dermatologist's office, so results may differ between the two routes.
For the treatment itself — what a session involves, in-office versus at-home devices, and how courses are priced — our red light therapy guide covers it end to end.
Cleveland Clinic's safety finding is short-term and conditional: red light therapy appears safe when used as directed, but misuse can damage skin or eyes, and the long-term safety of the devices is not known. Eye protection is advised — ask whether it is provided at every session.
Frequently asked questions
Does red light therapy really work?
It depends on the claim.
Cleveland Clinic calls red light therapy an emerging treatment and says more clinical trials are needed to confirm its effectiveness.
A 2014 controlled trial of 136 volunteers found that 30 twice-weekly sessions of red light improved skin complexion, roughness and collagen density compared with controls.
A 2017 meta-analysis found low-level laser therapy superior to placebo for hair growth in men.
For weight loss, cellulite, cancer and depression, Cleveland Clinic finds no scientific evidence.
Is red light therapy FDA-cleared or FDA-approved?
Devices are cleared, not approved.
Light-based devices are Class II devices cleared through the FDA's 510(k) process, with cleared categories including over-the-counter wrinkle reduction, over-the-counter red and blue light devices for mild-to-moderate acne, laser combs for male androgenetic alopecia and non-thermal lasers for adjunctive pain therapy.
Each clearance covers only the indication in that device's own submission, so ask which one applies to the device in front of you.
How many red light therapy sessions does it take to see results?
There is no confirmed number.
Cleveland Clinic describes the usual course as ongoing sessions, typically one to three a week for weeks or months.
We found no source establishing a standard time to results; the 2014 skin trial measured its outcomes after 30 twice-weekly sessions.
Ask any provider you consult how many sessions they recommend and what result the course is meant to produce.
Does red light therapy work for weight loss or cellulite?
Cleveland Clinic states there is no scientific evidence supporting red light therapy for weight loss or cellulite removal, and none for cancer or mental health conditions such as depression and seasonal affective disorder.
We found no support for "detox" claims in the sources we checked either.
If a provider markets a red light bed for fat loss, the claim sits beyond what the reviewed evidence supports.
Is red light therapy safe?
Short term, Cleveland Clinic says red light therapy appears safe when used as directed.
The limits matter: misuse can damage skin or eyes, the long-term safety of the devices is not yet known, and eye protection is advised.
At-home devices are generally safe too, per Cleveland Clinic, but may be less powerful than office devices, so results may differ.
Sources
Every number on this page comes from one of these sources and was checked against it.
- Red Light Therapy: Benefits, Side Effects & Uses · Cleveland Clinic
- api.fda.gov · U.S. Food and Drug Administration
- A controlled trial to determine the efficacy of red and near-infrared light treatment in patient satisfaction, reduction of fine lines, wrinkles, skin roughness, and intradermal collagen density increase · Wunsch et al., Photomed Laser Surg, 2014
- Light-emitting diodes in dermatology: A systematic review of randomized controlled trials · Jagdeo et al., Lasers Surg Med, 2018
- Light therapies for acne · Barbaric et al., Cochrane Database Syst Rev, 2016
- The effectiveness of treatments for androgenetic alopecia: A systematic review and meta-analysis · Adil et al., J Am Acad Dermatol, 2017
- Systematic review of photobiomodulation for the management of oral mucositis in cancer patients and clinical practice guidelines · Zadik et al., Support Care Cancer, 2019
Medical disclaimer. MedSpaStandard is for education only and is not medical advice. Talk to a licensed provider about your own health, and check any provider's license with your state board.