Treating acne with light therapy – what can red light and laser do?
Acne is the most common skin condition: it affects almost everyone during adolescence, but adult acne also persists for more and more people into their thirties and forties. Light therapy is one of the most actively researched drug-free methods in this field – dermatological literature now discusses the role of lasers and light devices in acne treatment in dedicated reviews, with a favourable safety profile.3
This article explains what causes acne, how different colours of light affect it – because blue and red light work on two different fronts – and how you can use a red-light low-level laser at home to treat mild to moderate inflammatory acne. I also want to set the boundary clearly from the outset: severe, nodular acne that threatens to leave scars is a job for a dermatologist – in that situation, starting medication in good time can protect the skin from permanent scarring.
Key point
Light attacks acne on two fronts: blue light (400–470 nm) targets acne bacteria, while red light (630–660 nm) calms inflammation and supports skin healing. For home laser treatment, the red range is the one supported by evidence: in a comparative study, the number of acne lesions on the side of the face treated with a 630 nm red laser fell to a fraction of the original level over 10 weeks – from an average of 27.7 to 6.3.2 For acne, choose a red-light device.
What causes acne? Four interlocking processes
Acne is not a condition caused by “neglected skin” – this is important to say, because excessive washing and scrubbing are more likely to make things worse. A spot is the end result of four interconnected processes.
One: the sebaceous glands – mainly under hormonal influence – produce more sebum; this is why acne starts during puberty and why it fluctuates with the menstrual cycle for many people.
Two: abnormal keratinisation of the hair follicle opening: dead skin cells do not leave normally but block the pore – this is a comedone.
Three: acne bacteria (Cutibacterium acnes), which are normally present on the skin, multiply in the blocked, sebum-rich pore.
Four: the immune system responds – inflammation develops, producing the red, painful, pus-filled spot.
Treatments act on these four processes: dermatological active ingredients mainly target keratinisation and bacteria, while light therapy – as you will see shortly – targets bacteria and inflammation. That is why the two approaches can be combined well.
How does light affect acne?
During its metabolism, acne bacteria accumulate compounds called porphyrins – and that is their weakness: porphyrins absorb blue light (400–470 nm). This causes reactive oxygen species to be released inside the bacterium, damaging the bacterium itself. Blue light is therefore a targeted, chemical-free “bacteria hunter” – this is one of the longest-described mechanisms of light-based acne treatment, and dermatological reviews also report favourable results with blue-light LED devices.3
An important distinction: blue light is delivered by LED panels and light masks – this is a different device category from low-level lasers. They are not competitors but two different fronts in the same battle.
Red light (630–660 nm) penetrates deeper into the skin and works there in the familiar way of low-level laser therapy: it reduces inflammatory signalling, stimulates cellular energy production and local circulation, and supports re-epithelialisation. In other words, it calms the most troublesome part of a spot – the red, painful inflammation – and may help marks fade faster. A dermatological review of LLLT discusses acne and acne scars among the conditions that may respond favourably to light therapy.1
The most telling data come from a study that compared the two wavelengths on the same patient: one side of the face was treated with a 630 nm red laser and the other with an 890 nm infrared laser, twice a week for 12 sessions. On the red-light side, the lesion count fell from 27.7 to 6.3; on the infrared side, there was no meaningful change.2 For acne, therefore, not just any laser will do: the red range is the one to choose.
Light-based acne treatment is now an established chapter in dermatology. According to a recent professional review, most high-level evidence concerns photodynamic therapy (PDT – light treatment combined with a photosensitising agent, performed in a clinic), which produced better results than conventional topical and oral treatments in some comparisons; blue light and pulsed light devices also showed favourable outcomes.3 A systematic review of pulsed dye laser treatment for inflammatory skin diseases specifically lists it as a recommended treatment for acne.4
The honest footnote is this: the studies used many different devices and settings, so researchers are calling for more consistent protocols. In practical terms, this means choosing a device with an evidence-based wavelength and giving the course 4–8 weeks before judging it.
Home treatment protocol – and basic skin care
| Question | Recommendation |
|---|---|
| Which light? | Red range: 630–660 nm – this produced the measurable reduction in lesion count in the study2 |
| Where and how much? | Target the inflamed spots and their immediate surroundings, 4–6 J/cm² per point – not the entire face |
| How often? | Daily or every other day; the study protocol used 2 treatments per week, for 12 sessions2 |
| For how long? | A 4–8-week course – the first meaningful change is typically visible after 2–4 weeks |
| What should you do before treatment? | Treat clean, make-up-free skin; do not let the treatment head touch a pus-filled spot (scan without contact), and disinfect it after use |
Light does not work in isolation – the daily basics of acne-prone skin are just as important: gentle cleansing twice a day (not with soap and without scrubbing); non-comedogenic moisturiser and make-up; and avoiding squeezing spots – the inflammation of a squeezed spot spreads deeper and can scar. Light therapy can be used alongside dermatological active ingredients (benzoyl peroxide, topical retinoids and, if necessary, antibiotics), with one timing rule: retinoids increase photosensitivity, so use them in the evening and carry out light treatment at a different time of day.
My advice
The most common mistake in acne treatment is changing things too impatiently: a new product, a new method and a new hope after two weeks – while none of them has been given enough time. Take a photo in good light when you start, then take another in the same place and the same way every week – and after 8 weeks, make your decision based on the pictures, not on your daily mood in the mirror. There is also a boundary that I consider important as a doctor: if your acne is nodular, deep or painful, or scars are starting to form, do not continue experimenting alone. See a dermatologist. Modern medication can treat severe acne effectively, but a scar that develops in the meantime may stay with you – asking for help early is the best decision for preserving your skin.
Which device is suitable for acne?
The message from the research is clear: acne calls for a red-light device – from our range, this is the Personal-Laser L200:
Personal-Laser L200
A pocket-sized, 42-gram, 660 nm red laser – it works precisely in the range found to be effective in the studies. It is a specialist device for superficial skin problems: ideal for targeted treatment of inflamed spots, and the same device can also be used for cold sores, small wounds and scars.
An important, honest clarification: 808 nm infrared devices (such as the Personal-Laser L400) are intended for deep-tissue problems – joints, tendons and muscles. In the comparative study, the infrared range did not produce meaningful improvement for acne2, so for acne treatment specifically, we recommend a red-light device. You can find the full range in the low-level laser category.
When should you NOT treat acne with light at home?
- Severe, nodular, scarring acne – this requires dermatological care: delay can result in permanent scars, and home light treatment is not sufficient
- During an isotretinoin course – oral acne medication makes the skin photosensitive: use light treatment only with your dermatologist’s approval
- Taking a photosensitising antibiotic (e.g. doxycycline) – tetracyclines, often prescribed for acne, can cause photosensitivity: consult your doctor first
- Uncertain diagnosis – rosacea, perioral dermatitis and fungal folliculitis can look deceptively similar to acne but require different treatment: see a dermatologist first if in doubt
- Pregnancy – only after medical consultation
- Around the eyes – never direct laser light into the eye or at the eyelid
When should you see a dermatologist?
If acne appears suddenly in adulthood; if it flares after starting medication; if it is accompanied by fever or joint pain; if it is scarring; or if 8 weeks of consistent home treatment produce no improvement. You can find general safety information about light therapy in the low-level laser contraindications article.
Frequently asked questions
With targeted treatment, individual inflamed spots typically calm down within days – but improvement in the overall appearance of the skin is measured in weeks: study protocols followed patients for 10–12 weeks, and improvement developed gradually.2 A realistic schedule is 2–4 weeks before the first visible change and 8 weeks before making a proper assessment. A weekly photo tells you more than the mirror does each day.
The antibacterial mechanism of blue light is well described, and professional reviews also report favourable results with blue-light devices3 – so they should not be dismissed. Two things are worth knowing: the light output of home LED masks varies greatly (and weaker output means weaker effects), and blue light acts mainly on bacteria, less so on inflammation. The most complete home approach combines the two fronts: blue LED over a larger area for prevention, and a red laser targeted at inflamed spots.
Yes. In fact, active ingredients and light work on different processes, so their effects can complement each other. The practical rules are: use light treatment on clean, product-free skin (light first, active ingredient afterwards); use retinoids in the evening because they increase photosensitivity; there is no timing restriction with benzoyl peroxide, but do not apply it immediately before treatment. If you take oral acne medication (an antibiotic or isotretinoin), ask your doctor first – some of these medicines cause photosensitivity.
On fresh, red scar marks (which are actually still post-inflammatory discolouration), red light may help them fade faster by supporting re-epithelialisation and circulation – the dermatological review discusses acne scars among the conditions that may respond favourably to light therapy.1 Older, indented, fibrous scars, however, require clinic-based treatments (fractional laser or chemical peeling). Prevention gives you the greatest benefit: calming inflammation early – including with light – reduces the chance of scar formation. I have written a separate article on scar treatment.
With realistic expectations: targeted treatment can often noticeably reduce the inflammation of a spot caught early, while it is still developing – it becomes smaller and settles sooner. A fully developed pus-filled spot, however, has its own biological timetable: light may speed up the settling process, but it will not erase the spot overnight. The worst thing to do at this stage is squeeze it – that deepens the inflammation and leaves a scar. Light, patience and leaving it alone: that is the fastest genuine route.
What does the research say? Answers to readers’ questions
“How do you know that red light is exactly what acne needs?”
From an elegant study design: researchers treated one side of each patient’s face with a 630 nm red laser and the other with an 890 nm infrared laser – twice a week for 12 sessions, so each patient served as their own control. The result was clear: on the red-light side, the number of acne lesions fell from 27.7 to 6.3 over 10 weeks, while there was no meaningful change on the infrared side.2 That is why we say that wavelength is not a minor detail for acne – a red-light device is needed.
“Does dermatology take light therapy seriously, or is this just a wellness topic?”
It takes it seriously – professional reviews of light and laser treatment for acne are published regularly. According to a recent summary, most studies concern photodynamic therapy, which showed more favourable results than conventional topical and oral medicines in some comparisons; blue light and pulsed light devices also produced favourable outcomes, and light-based methods cause fewer side effects than medicines.3 Researchers are calling for more consistent protocols, but the direction is clear: light therapy is part of the recognised acne-treatment toolkit.
“What is generally known about dermatological applications of low-level laser therapy?”
According to a frequently cited review from Harvard’s photomedicine centre, red and near-infrared light activate cellular energy production and signalling pathways in the skin. Their dermatological benefits are varied: favourable effects have been described for wrinkles, acne and hypertrophic scars, burn healing, and inflammatory skin diseases – including acne – are among the conditions that may respond favourably, with virtually no side effects.1 Light therapy is therefore not a one-condition miracle device but a general support for skin regeneration – acne treatment is one well-documented chapter of that wider use.
Summary
What is this article about? A guide to light therapy for acne: what causes acne, how blue and red light affect it, which protocol to use for home treatment with a red laser, and how to fit light therapy alongside your skin-care routine and dermatological treatments.
Who is it for? People with mild to moderate inflammatory acne – teenagers and adults living with adult acne alike – who are looking for a drug-free adjunct.
Main message: Light works on two fronts: blue light acts on bacteria, while red light acts on inflammation. For home laser treatment, the evidence supports the red range (630–660 nm) – in the study, the lesion count fell to a fraction of the original level, while infrared light produced no change. The course lasts 4–8 weeks, with photographic documentation; severe, scarring acne requires a dermatologist.
Next step: Take a baseline photo, start daily targeted red-light treatment on the inflamed spots, maintain gentle skin-care basics – and assess the result from the pictures after 8 weeks. If you see scarring, do not wait: see a dermatologist.
Read more
- Low-level laser therapy for scars and keloids
- Treating cold sores with low-level laser therapy – a complete guide
- Low-level laser therapy for psoriasis
- Low-level laser therapy at home: how should you use it for different problems?
- Low-level laser therapy guide: how it works, dosage and laser classes
- Low-level laser contraindications: when should you not use it?
Scientific sources
- Avci P, Gupta A, Sadasivam M, et al. (2013). Low-level laser (light) therapy (LLLT) in skin: stimulating, healing, restoring. Seminars in Cutaneous Medicine and Surgery. PubMed: 24049929
- Aziz-Jalali MH, Tabaie SM, Djavid GE. (2012). Comparison of red and infrared low-level laser therapy in the treatment of acne vulgaris. Indian Journal of Dermatology. DOI: 10.4103/0019-5154.94283
- Li MK, Liu C, Hsu JTS. (2021). The use of lasers and light devices in acne management: an update. American Journal of Clinical Dermatology. DOI: 10.1007/s40257-021-00624-5
- Erceg A, de Jong EMGJ, van de Kerkhof PCM, Seyger MMB. (2013). The efficacy of pulsed dye laser treatment for inflammatory skin diseases: a systematic review. Journal of the American Academy of Dermatology. DOI: 10.1016/j.jaad.2013.03.029
