Photobiomodulation: Seeing the light
DermWorld highlights the most popular (and effective) applications of red-light therapies, and how to advise patients about the proliferation of products for at-home use.
Feature
By Heidi Splete, Contributing Writer, December 1, 2025
Photobiomodulation (PBM) — including low-level laser therapy, low-light therapy, or red-light therapy — involves the use of light waves to promote biologic change in the body by stimulating cellular activity. Although the field is still developing, PBM is becoming more popular in medicine, particularly in dermatology.
More research is needed to determine the optimal treatment parameters, but recent review articles and experts provided DermWorld with a primer on PBM and how it impacts clinical practice.
Why pay attention to PBM?
The interaction of light and tissue to achieve biological effects has advanced in recent decades, and is within the expertise of dermatologists, said Zakia Rahman, MD, FAAD, clinical professor of dermatology at Stanford University School of Medicine.
The explosion of social media has made consumers more aware of the potential applications of PBM for skin care, Dr. Rahman emphasized. These consumers are often current or future dermatology patients, and even those who have not tried PBM may be curious and want to discuss options with a dermatologist, she said. PBM does not create heat, coagulation, or vaporization; instead, red and near-infrared wavelengths of light target internal chromophore cytochrome c oxidase in the mitochondria, which produces adenosine triphosphate (ATP), the energy-carrying molecule found in all living cells, Dr. Rahman explained. “Think of PBM as adding a little energy into the batteries of your cells,” she said.
PBM is moving rapidly from niche labs into clinics and consumer devices, said Jill S. Waibel, MD, FAAD, medical director of Miami Dermatology & Laser Institute. “Dermatologists should be familiar with PBM because our patients are using it, often through direct-to-consumer products,” she said. PBM is being used for many conditions managed by dermatologists, such as wound healing, hair loss, acne, and radiation dermatitis, but it can interact negatively with other treatments, such as photosensitizing drugs and some procedures, and device claims and regulations are evolving, she added.
How PBM works
PBM uses light waves in the red-light spectrum (620-700 nm) and the near-infrared spectrum (700-1440 nm). Photons from red light (RL) and near-infrared light (NIR) are absorbed by cells and trigger a series of beneficial cellular events. Evidence shows that these light waves can induce cell proliferation and enhance differentiation of stem cells. In the clinical dermatology setting, PBM may be delivered via lasers or light-emitting-diodes (LEDs). At-home PBM devices available for patient use include combs, caps, masks, wands, headgear, and light panels. Patients should be cautioned about choosing safe products and managing their expectations, according to experts (see sidebar).
The PBM backstory
The MeSH (Medical Subject Headings) term for PBM was officially adopted by the National Library of Medicine in 2015, and the number of studies validating its use and effectiveness have increased, said Dr. Rahman. However, studies of the effects of red light on biological tissue date back to the 1960s, when Hungarian scientists investigated whether exposure to low energies of red light would cause mice to develop skin cancer, she said. Instead, the researchers found that those mice receiving red-light treatment sprouted more hair, and subsequent studies in mice — and humans — bolstered evidence of red light’s ability to promote hair regrowth, she said.
Early PBM products used in dermatology were red-light LED combs cleared by the FDA to promote hair growth, and studies have shown that red light penetrates the skin at shallow depths and stimulates growth of follicles, Dr. Rahman said. Evidence also suggests that this light causes vasodilation, and some hair growth products, such as topical minoxidil, harness that mechanism to stimulate hair growth, she said. “The dilation of blood vessels enables more blood and nutrients to reach the hair follicles,” she explained. “Red light has been shown to regrow thinning hair when used over multiple months, but the effects stop when the individual stops applying the red light,” Dr. Rahman noted.
“The effect on the follicle works when the light can reach the scalp, so combs or devices that separate hair and can shine the light on the scalp are the ones that are the most effective, which is why PBM caps are not ideal,” said Dr. Rahman. “By the time your hair follicles have miniaturized so much that a cap LED light could reach the scalp, the light treatment is less likely to result in significant improvement,” she said.
Dr. Rahman currently incorporates red-light devices into hair loss regimens. Other common office applications of PBM include reducing inflammation following other laser treatments, she noted.
PBM treatments continue to be popular for facial rejuvenation, and numerous devices are on the market with FDA clearance to reduce wrinkles, although with less evidence of success than hair regrowth, Dr. Rahman said. “LEDs are not lasers, so the light is not coherent; it scatters and can be less effective the farther away it is from the treating skin,” she noted.
Evidence, indications, and unknowns
PBM is increasingly used for dermatologic and non-dermatologic conditions, according to the expert authors of a recent JAAD continuing medical education review. These indications include a range of skin rejuvenation outcomes, as well as improvements in pain, inflammation, and fluid retention. PBM has also been used to promote wound healing, including diabetic foot ulcers, venous leg ulcers, and pressure sores. However, some of the strongest data support PBM’s value for patients with herpes simplex virus, side effects from cancer treatments, and for promoting hair regrowth in patients with alopecia.
Factors that guide the use of PBM in medicine include wavelength, energy density, fluence, and treatment duration. PBM treatment generally involves either lasers or LEDs with a targeted treatment area defined as mm2 or cm2, according to the JAAD review.
A major advantage of PBM is its non-invasiveness, which appeals to many patients seeking skin care for conditions including acne, wrinkles, scarring, and wound healing, according to David M. Ozog, MD, FAAD, FACMS, chair of the department of dermatology at Henry Ford Health in Detroit and professor of medicine at Michigan State University.
“Although safety and ease of use are the main advantages, benefits may also include treating not only the skin surface, but also the underlying tissue,” said Dr. Ozog, a coauthor on both the CME review and a consensus statement on the clinical applications of photodynamic therapy published in JAAD in 2025.
PBM is not yet a significant part of most dermatology practices, Dr. Ozog noted. However, he often recommends PBM to patients as an adjunct for skin rejuvenation and wound healing.
Indoor light context
With the widespread shift to white LEDs for indoor lighting, which are typically blue rich and comparatively low in deep red and near infrared output, many people who spend most of their time indoors receive far less red/NIR exposure than they would from natural sunlight, said Dr. Ozog. Early-morning and late day sunlight are particularly enriched in red and near infrared wavelengths; staying indoors reduces that exposure, he said. “For patients with little ambient red/NIR exposure, the incremental effects from an at-home PBM device may be more noticeable,” he added.
Secrets of at-home PBM success
Use of PBM devices at home is generally safe, but effectiveness varies widely, according to experts. However, the most important tip for patients to help them get the most from their purchase is to choose devices with FDA clearance, according to several experts.
PBM has low systemic risk, but it is not risk-free, Dr. Waibel said. Advise patients to confirm the regulatory status of a device and its indications. “FDA-cleared does not mean FDA-approved,” she cautioned. High-risk products such as drugs are FDA approved. Medical devices are typically FDA cleared. The FDA approval process is separate and has a higher standard of scrutiny than that of the FDA clearance process.
“Let patients know that online marketplaces for PBM devices are like the Wild West; they are littered with red light wands, masks, and even beds,” Dr. Rahman said.
Makers of devices with FDA (510k) clearance have gone through the process of conducting studies and meeting the formal requirements for safety with the FDA, and this should be a minimum requirement if someone wants to purchase a PBM device for home use, Dr. Rahman emphasized.
Putting PBM into practice
Jared Jagdeo, MD, FAAD, an associate professor of dermatology and director of the Center for Photomedicine at SUNY Downstate Health Sciences University and a member of the scientific advisory board for Omnilux, frequently integrates PBM as a stand-alone home therapy and as an adjunctive therapy following laser procedures, such as intense pulsed light (IPL) and fractional CO₂ resurfacing. “This approach leverages PBM’s ability to modulate cellular activity, thereby reducing inflammation and promoting faster tissue repair, which may enhance patient outcomes beyond what monotherapy can achieve,” said Dr. Jagdeo, who also served as a coauthor on the consensus statement and the review.
“PBM may enhance post-procedural outcomes by promoting collagen remodeling, resulting in a smoother recovery and improved aesthetic results in skin rejuvenation and photoaging treatments,” Dr. Jagdeo noted. “Clinical studies have shown that adding PBM can be especially beneficial for patients undergoing aggressive aesthetic interventions by reducing downtime and optimizing healing with no additional risk,” he added.
The JAAD review outlined treatment techniques for some of the more common uses of PBM in the dermatologist’s office.
Cancer care collaboration
PBM has shown Level IA evidence for reducing the impact of various side effects from cancer therapy, including acute radiation dermatitis and mucositis, as well as lymphedema after mastectomy. For radiation dermatitis patients, data support wavelengths in the 808-905 nm range, in durations of 1-12 minutes, administered immediately after the radiation therapy for optimal results. Mucositis wavelengths are generally lower, in the range of 620-670 nm. Post-radiation therapy treatment with PBM at fluences ranging from as low as 0.15 J/cm2 to as high as 34.71 J/cm2 have been reported for acute radiation dermatitis, and from 1-12 J/cm2 for mucositis, with no significant adverse events, according to the review article.
Help for hair loss
PBM has been used to treat multiple types of alopecia in both men and women, and data show an association between PBM use and hair regrowth, length, and density. Studies of this application show wavelengths ranging from 630-800 nm. Reported fluences range from 0.1-4 J/cm2. The most common dosing is sessions of 10-25 minutes, 2-3 times a week for 16-24 weeks, according to the JAAD review. The level of evidence supporting PBM for alopecia is strong and includes meta-analyses from randomized controlled trials. A recent meta-analysis showed significant improvement in hair density among patients with androgenetic alopecia who used PBM devices compared to controls. Notably, the style of device didn’t matter — effectiveness was similar among patients who used comb-style devices and those who used hat/helmet devices.
Healing herpes simplex
Robust data support PBM for healing herpes and reducing outbreaks, said Dr. Ozog. “Evidence supports PBM for herpes labialis to aid healing and, with maintenance courses, to lengthen time between recurrences,” he said. Protocols commonly use red to near infrared wavelengths of approximately 630–830 nm (either 670–690 nm or 780–830 nm, delivered over short sessions of about 2-5 minutes per site) 2-3 times weekly during an outbreak; prophylactic courses have also been studied. Use of PBM during active outbreaks involving treatments of 670 nm and 1.6-4.8 J/cm2 has resulted in an elimination of outbreaks, and higher treatments of 690 nm and 48 J/cm2 used during periods of inactive infection significantly reduced recurrences, according to studies referenced in the review.
Aesthetic applications
In contrast to medical applications, the evidence for PBM in cosmetic dermatology, such as acne and wrinkle reduction, is less conclusive, Dr. Ozog said. “PBM has shown stronger results for acne than for wrinkles, but acne-causing bacteria tend to repopulate once treatment stops,” he said. “Patients should be made aware that results may be short lived.” The evidence for PBM in acne care and wrinkle reduction is moderate (Level IB) with evidence from at least one clinical trial, according to the JAAD review article. The reported wavelength range for PBM in acne is 620-1072 nm, and reported wavelengths for skin rejuvenation have extended to 1072 nm. Common reported fluences range from 12-37 J/cm2, and treatment is often delivered via face masks used by patients at home.
Range of wound relief
A strong level of evidence supports PBM for wound care both for healing and pain reduction, according the JAAD CME review. A recent meta-analysis from 2021 showed significantly greater reduction in size and increased rates of healing of diabetic foot ulcers in patients treated with PBM versus controls. Studies of wound care have involved wavelengths in the 630-980 nm range. Treatment durations are longer for wound care than other applications, and data on PBM treatment of ulcers show wavelengths of 630-980 nm, with durations ranging from 2 minutes to as long as 20 minutes, given 2-7 times per week for at least 4 weeks. However, the reported fluences are often lower, ranging from 2-12 J/cm2. Scar care fluences at the same wavelength have been reported at 13 J/cm2.
Patients’ guide to PBM at home
Put safety first. Remind patients to use eye protection and to read instructions for use of home devices, even something that seems as simple as a comb, Dr. Jagdeo said. Ideally, patients should seek out devices that have been studied in peer-reviewed clinical trials published in respected medical journals, he said.
Always use built-in eye protection or external eyewear if the device instructs it, Dr. Waibel noted. “Although most red/NIR PBM is non-ionizing and low power, direct high-irradiance exposure to the retina should be avoided, and masks that cover the eye area may omit full eye protection,” she said. The device specs matter, too. Remind patients to follow the manufacturer’s directions for a device’s wavelength, irradiance, fluence, and treatment time, she added.
Manage expectations. PBM at home should be considered adjunctive, not curative, with benefits accruing over weeks of consistent use, Dr. Jagdeo noted. “Consumer devices, although supported for various medical and cosmetic purposes, tend to produce modest, gradual improvements and are best used as part of a comprehensive regimen,” he said.
“The efficacy of these at-home treatments will be much less than light-based treatments in the dermatologist’s office, which are used at wavelengths and intensities to have photothermal, photoacoustic, photochemical, or even photoablative effects,” said Dr. Rahman. However, home-use devices can often complement the treatments performed in the office, she said.
Consider skin types. Patients with photosensitivity and photodermatoses should consult a dermatologist to minimize the risk of improper use and the rare side effects of at-home PBM devices, said Dr. Jagdeo. “Patients with non-Caucasian skin also need to be aware that their skin may be more sensitive to PBM,” he said. “People with skin of color should begin use of a PBM device with conservative settings and twice-weekly, non-consecutive daylight therapy, to ensure no adverse effects, then gradually increase their treatment regimen to alternating days to minimize the risk of adverse effects such as prolonged pigmentation, erythema, or edema,” Dr. Jagdeo said.
Identify medication interactions. Review photosensitizing drugs, such as certain tetracyclines, sulfonamides, some psychedelics, or topical photosensitizers, and conditions, such as lupus and porphyria. Individuals with photosensitivity disorders and a history of photosensitizing cancer treatments should steer clear of PBM, said Dr. Waibel.
Be committed. Most at-home PBM devices require consistent use, usually several sessions per week for 8-12 weeks, to see skin benefits, in part because of the lower irradiance, Dr. Waibel said.
Mind the details. “Make sure patients understand that they must match the light to the indication for best results,” said Dr. Waibel. “Blue light is often used for acne because of its antimicrobial properties, while red is more common for tackling inflammation and for stimulating collagen and hair growth,” she said.
Know when to stop. If a patient using a device at home reports that their skin condition has worsened, or if they experience new hyperpigmentation, pain, or unusual photosensitivity, they should stop using the device and come to the office for an evaluation, Dr. Waibel emphasized. Avoid PBM use near a healing skin cancer or on suspicious lesions without prior evaluation, she added.
When to pass or proceed with caution
PBM is generally considered safe and non-invasive, but that doesn’t mean throwing caution to the wind, experts agreed. Most patients tolerate PBM treatments well, with erythema being the most common side effect.
However, a key rule of PBM: More isn’t always better, Dr. Ozog said. PBM exhibits a biphasic (hermetic)-dose response, so excessively high doses or prolonged sessions can lessen benefits and may carry unknown risks, said Dr. Ozog. “Devices also vary widely; some may be ineffective; therefore, clinically reasonable dosing and schedules are preferred over very long exposures,” he said.
Patients who might ask whether PBM’s properties would promote hair growth in unwanted places can be reassured that they will not look like werewolves, said Dr. Rahman. “We don’t have terminal hairs all over our faces,” she said. However, “I caution anyone with a history of pigmentary disorders such as melasma to avoid exposure to visible light, so those patients might want to avoid using PBM devices,” she said. “Anyone with active skin infection, open wounds, light-sensitive skin conditions, or a history of seizure disorder should avoid using PBM devices as well,” she added.
“While PBM is generally safe for adults without inducing DNA damage from red light, even at high fluences, patients with known photosensitivity or photodermatoses warrant particular caution as PBM may exacerbate these conditions,” Dr. Jagdeo said. PBM should be used with caution and under the guidance of a physician for treating children, as safety data in pediatric populations are limited, Dr. Jagdeo added. “Eye protection is also important as certain devices may emit light that can cause temporary or long-lasting injury,” he emphasized. However, most adverse effects associated with PBM are mild and self-limiting, including transient discomfort and erythema. “Severe burns, scarring, or sepsis are rare and typically reflect misuse or inappropriate therapy parameters,” Dr. Jagdeo said.
“Familiarity with PBM allows dermatologists to guide patients amid the proliferation of at-home devices and marketing claims,” said Lucie Joerg, a research fellow and medical student working with Dr. Jagdeo at SUNY Downstate Health Center for Photomedicine.
“Staying informed on PBM ensures evidence-based patient-physician discussions, prevents misuse, and supports PBM as an adjunct to traditional therapies when appropriate,” she added.
