Can red light therapy actually regrow hair? Experts give their verdict

When people first notice their hair is thinning, there’s a good chance they’ll do anything to save their strands – but many of the solutions out there don’t always work. That’s why it’s important to stick to thinning hair strategies that are tried and true, with science to back them up.

To find out whether red light therapy for hair really works and who it’s best for, we went straight to the experts. Read on to find out everything you need to know about what to realistically expect from the treatment.

‘Red light therapy for hair growth works by delivering low-level light energy to the scalp, which helps stimulate cellular activity within the hair follicle,’ says Dr Dendy Engelman, FACMS, FAAD, double board-certified cosmetic dermatologist and Mohs surgeon at Shafer Clinic NYC.

‘The light penetrates the skin and supports mitochondrial function, improving circulation and encouraging follicles to remain in the active growth phase longer. I often describe it as creating a healthier environment for the scalp and follicle to function more efficiently. While it is not an overnight solution, it can be a very supportive tool for improving overall hair density and reducing shedding over time.’

Most of the clinical data is based on medical-grade low-level laser therapy (LLLT), which has been shown to dilate capillaries supplying the follicle and help extend the growth phase of the hair cycle, explains Shab Caspara, NYC trichologist and founder of Caspara Hair Preservation Studio.

‘In my studio, I use light therapy as part of a comprehensive protocol to enhance the effects of topicals, supplements and in-office treatments,’ she says. ‘Red light therapy is more effective for slowing shedding, improving hair quality and supporting thicker, healthier strands than for dramatically regrowing hair in completely dormant areas. Most people notice reduced shedding first, followed by improved density, strength and scalp health over several months.’

A review article in Photodermatology, Photoimmunology & Photomedicine showed that multiple studies have shown that red light can ‘promote hair growth in men and women with androgenic alopecia’.

One ex vivo study, conducted on hair follicles from real hair-loss patients, showed that red light could keep hair follicles in the growth phase of the hair cycle longer, delaying hair shedding. ‘The researchers found that the red light had anti-inflammatory effects that protected the hair follicles,’ says US Good Housekeeping Institute Beauty Lab Reviews Analyst Chiara Butler. ‘They also found that it improved a cell signaling pathway called Wnt/β-catenin, which is “negatively influenced by the increased androgen in androgenetic alopecia patients”. A review of patients who were treated with professional-grade red light therapy for long COVID-related hair loss found that “LED therapy is safe, well tolerated and seems to be a promising therapeutic option for telogen effluvium in patients with long COVID.”’

At-home devices can be effective, according to a review in the Journal Of Clinical And Aesthetic Dermatology. ‘The products that had clinical studies that showed an effect were the Capillus 272 Pro, the Hairmax laser combs 9 and 12, and the iGrow helmet,’ Butler says. ‘The helmets that showed results all contained laser diodes, not just LED lights.’

However, it’s important to note that these studies are small and short-term, so more research is needed.

‘Red light therapy tends to work best for individuals experiencing mild to moderate thinning, especially androgenetic hair loss or stress-related shedding,’ Dr Engelman says. ‘It can be beneficial for both men and women who want a non-invasive option to support hair growth and scalp health. However, it may be less effective for patients with extensive scarring alopecia or areas where follicles are no longer active. Anyone with a scalp condition, unexplained hair loss or underlying medical concerns should first speak with a dermatologist to determine the root cause before starting treatment.’ It’s also important to see a dermatologist when you first notice hair thinning because you may be missing a larger health issue.

Caspara adds that red light therapy can also be helpful for postpartum hair loss, but it’s less effective for advanced hair loss where follicles have been inactive for years or replaced with scar tissue. Butler cautions that other contraindications include taking photosensitising medications, epilepsy, light-induced severe headaches, a diagnosis of lupus, known light sensitivity or a diagnosis of skin cancer of the head, scalp or neck.

The experts unanimously agreed that the most important factors are consistency and following each device’s specific instructions. To stay on schedule, it’s a good idea to incorporate it into a routine, such as using it at the same time each evening, to help stay consistent.

‘Most at-home devices are designed to be used several times per week for anywhere from 10 to 30 minutes per session, depending on the technology and strength of the device,’ Dr Engelman says. ‘Consistency matters much more than overusing it, and using it more frequently than recommended will not necessarily accelerate results. Hair growth is gradual, so most people need at least three to six months of regular use before seeing noticeable improvement.’ Continued maintenance treatments are generally required to maintain results.

Keep in mind that the device needs to deliver light directly to the scalp, not just the hair. ‘Devices with parting mechanisms or teeth tend to work better for people with thicker or longer hair because they improve scalp exposure,’ Caspara says. ‘I also recommend using it on a clean scalp free of heavy buildup, oils, or styling products that can interfere with penetration.’

Following the manufacturer’s instructions is crucial to avoiding side effects. ‘Side effects are minimal when devices are used correctly,’ Caspara says. ‘Overuse beyond the recommended protocol is not necessarily beneficial and may create unnecessary stress on the scalp tissue. Similar to exercise, follicles also need recovery time between stimulation sessions, which is why following evidence-based treatment schedules matters.’

However, Dr Engelman recommends that patients with very sensitive skin or certain medical conditions always discuss treatment with their physician first. ‘Occasionally, some people may experience mild scalp irritation, dryness, warmth or temporary tenderness, particularly if the device is overused,’ she says. ‘Overall, compared to many other hair loss treatments, it is considered a relatively low-risk option.’

‘When selecting an at-home red light therapy device for hair growth, I recommend looking for one that uses clinically studied wavelengths, has strong safety data and is designed specifically for scalp use,’ Dr Engelman says. ‘Comfort and convenience also matter because patients are much more likely to remain consistent with a device that fits easily into their lifestyle. Devices that allow even scalp coverage and have sufficient light intensity tend to perform better than weaker or poorly designed options. I also encourage patients to purchase from reputable brands with transparent clinical information.’

Medical-grade laser devices are generally more effective for active thinning and hair loss, while lower-strength LED devices may be better suited for prevention or maintenance, according to Caspara.

Be aware that because red light devices for hair are categorised as medical devices rather than drugs, they are FDA-cleared in the US rather than FDA-approved. ‘FDA clearance means the device has demonstrated safety and measurable performance compared to similar devices already on the market,’ Caspara says. However, that doesn’t necessarily mean guaranteed results, though Dr Engelman tells her patients to steer clear of unapproved devices.

‘Realistically, people can expect to see gradual improvements in hair fullness, reduced shedding, and healthy-looking hair with consistent use over several months,’ Dr Engelman says. ‘Most patients will not suddenly regrow a full head of hair, but many notice improved density, stronger strands, and less visible thinning. Results tend to be best when treatment begins early, before significant follicle miniaturisation has occurred. Consistency and patience are extremely important because hair growth cycles naturally move slowly.’

However, it’s important to remember that red light therapy should be used as part of a comprehensive hair loss treatment plan. ‘One of the biggest misconceptions is that red light therapy alone can fully reverse all forms of hair loss,’ Caspara says, explaining that it works best as part of a broader hair loss treatment plan. It’s a supportive tool, not a standalone cure, and is most effective when combined with treatments that address the root cause of thinning, such as scalp care, topicals, nutrition, hormones, and underlying deficiencies.