THE CURE INDEX
Helio Cure's evidence score based on human clinical trials for red light therapy.
Spot baldness (also called alopecia areata) is a form of hair loss that produces one or more round or oval bald patches on the scalp or body.
Across 4 human studies covering 81 participants, red light therapy was found effective for spot baldness, but results varied, prompting cautious optimism and the need for further research. A CURE Index score of 56 out of 100 was recorded for this condition, indicating moderate confidence.
Hair regrowth in treated patches was associated with red light therapy, though the degree of improvement differed between studies of spot baldness.
3 clinical trials and 1 observational study made up the 4 studies reviewed, and 3 reported effective outcomes while 1 reported partially effective outcomes.
The most cited wavelength reported was near-infrared light near 904 nm, within a broader range of 308 to 1600 nm. Sessions lasted 5 seconds to 3 minutes, delivered 1 to 21 times per week, over a therapy duration of 21 to 150 days.
EVIDENCE AT A GLANCE
The numbers behind the verdict.
MOST CITED WAVELENGTH
The wavelength appearing most often in studies that showed benefit for spot baldness.
904 nmTREATMENT PROTOCOL RANGES
The lowest and highest values used across spot baldness studies.
| PARAMETER | RANGE |
|---|---|
| Wavelength | 308-1600 nm |
| Session Duration | 5 seconds-3 minutes |
| Session Frequency | 1-21 per week |
| Therapy Duration | 21-150 days |
Note: We have excluded meta-analyses and reviews from scoring, but the list of human studies below contains them for your reference.
7 Human Studies on Red Light Therapy for Spot Baldness
Local and Whole-Body Phototherapy Showed Similar Results for Spot Baldness
Comparing local phototherapy against whole-body irradiation, a 2026 observational study reviewed treatment response in 49 patients with spot baldness. 32 patients received local ultraviolet light at 308 nm and 17 received whole-body ultraviolet light at 309 to 313 nm, each completing at least 10 sessions at a frequency of about 21.3 sessions per week, with hair loss severity tracked using a standard score for how much scalp hair is missing. Researchers found that local and whole-body phototherapy produced a similar improvement in that score. Better responses were linked to first-onset disease, treatment starting within a year of onset, and age over 40. Hair regrowth was typically observed after 20 to 30 treatment sessions.
- Study Type
- Observational Study
- Participants
- 49
- Treated Area
- Scalp And Body
- Wavelength(s)
- 308, 309-313 nm
- Session Frequency
- 21.3 per week
Study Title: Efficacy of Local and Whole-Body Phototherapy for the Treatment of Various Types of Alopecia Areata.
Spot Baldness Patch Regrew Hair After Red Laser Treatment
A clinical trial published in 2023 tested photobiomodulation (PBM) using a continuous-wave red laser at 660 nm as a stand-alone treatment for spot baldness in a single adult patient. The laser was applied in contact with the right side and temple of the scalp for 10 seconds per session, 21 times per week, over 21 days, delivering an irradiance of 1000 mW/cm² and a dose of 10 J/cm². Hair appeared to regrow in the treated area by the end of treatment, though a single case cannot establish how well this approach works more broadly.
- Study Type
- Clinical Trial
- Participants
- 1
- Treated Area
- Scalp
- Wavelength(s)
- 660 nm
- Distance
- Contact
- Session Duration
- 10 seconds
- Session Frequency
- 21 per week
- Therapy Duration
- 21 days
- Study Scope
- Autoimmune Alopecia
Study Title: Photobiomodulation With a Continuous Wave Red Laser (660 nm) as Monotherapy for Adult Alopecia Areata: A Case Presentation.
Children with Severe Spot Baldness Responded Well to Light Therapy
Among 329 children with severe, extensive spot baldness pooled from 10 studies, a 2022 systematic review compared topical immunotherapy, Anthralin, and light or laser therapy. The light-based treatments reviewed used wavelengths of 308, 3060, and 3080 nm, spanning ultraviolet through far-infrared, delivered 2 times per week over about 90 days, at doses of 0.005 to 0.05 J/cm². The authors concluded that light or laser therapy was associated with an average response rate of about 52.55% and complete hair regrowth in up to 63.61% of cases, comparable to topical immunotherapy and better than Anthralin. The review described these light-based methods as well tolerated in children, with no serious side effects reported.
- Study Type
- Review
- Participants
- 329
- Treated Area
- Head
- Wavelength(s)
- 308, 3060, 3080 nm
- Session Frequency
- 2 per week
- Therapy Duration
- 90 days
Study Title: A systematic review on the treatment of pediatric severe alopecia areata by topical immunotherapy or Anthralin (contact sensitization) or low-level light/laser therapy (LLLT): focus on efficacy, safety, treatment duration, recurrence, and follow-up based on clinical studies.
8 of 10 Studies Linked Light to Spot Baldness Regrowth
Across 422 participants pooled from clinical trials and case reports, a 2018 review assessed monochromatic light devices for spot baldness. The review covered a 308 nm excimer laser alongside low-level laser therapy (LLLT) and other light sources spanning ultraviolet, near-infrared, and infrared light from 308 to 1550 nm, applied to the scalp, beard, eyebrows, mustache, and the arms and legs, in sessions of 10 to 15 minutes, 2 to 24 times per week, at doses of about 0.002 to 2.3 J/cm². 8 of 10 clinical trials, plus 2 case reports, showed hair regrowth with the 308 nm excimer laser, while LLLT produced regrowth in a smaller set of trials, the review reported. The review also noted that larger, double-blinded trials are still needed to confirm how well LLLT works for spot baldness.
- Study Type
- Review
- Participants
- 422
- Treated Area
- Head
- Wavelength(s)
- 308, 904, 1060, 1064, 1550 nm
- Session Duration
- 10-15 minutes
- Session Frequency
- 2, 11-12, 24 per week
Study Title: A review of monochromatic light devices for the treatment of alopecia areata.
Near-Infrared Laser Produced Hair Regrowth in Most Spot Baldness Patches
Researchers in Iraq tested a pulsed near-infrared diode laser for spot baldness in a 2006 clinical trial. 16 patients (11 males and 5 females, ages 4 to 50, mean age 26.6) with 34 resistant scalp patches received 4 weekly sessions of 904 nm light delivered to the scalp, eyebrows, beard, and mustache, each lasting 5 seconds, over 28 days, with 1 patch left untreated as a control in patients with multiple patches. The trial found hair regrowth in 32 of 34 treated patches (94%), most of which regrew as thick, fully grown hair in its original color. Many of these responses appeared within the first week of treatment.
- Study Type
- Clinical Trial
- Participants
- 16
- Treated Area
- Head/Face
- Wavelength(s)
- 904 nm
- Distance
- Contact
- Session Duration
- 5 seconds
- Session Frequency
- 4 per week
- Therapy Duration
- 28 days
Study Title: Use of the pulsed infrared diode laser (904 nm) in the treatment of alopecia areata.
Review Found Mixed Evidence for Light Therapy in Spot Baldness
This 2013 review examined the use of electromagnetic radiation, including low-level lasers, for hair regrowth, including in spot baldness. Drawing on a pool of 877 participants across the reviewed studies, treatments used wavelengths from 308 to 1550 nm applied to the scalp, in sessions of 20 seconds to 15 minutes, delivered 3 times per week over a course of about 182 days, at irradiances of 10 to 5000 mW/cm² and doses of 0.15 J/cm² and 15 to 40 J/cm². According to the review, the evidence for hair growth devices was inconsistent across studies, with the authors noting that independent, peer-reviewed randomized trials showing clear benefit are still lacking.
- Study Type
- Review
- Participants
- 877
- Treated Area
- Scalp
- Wavelength(s)
- 308, 600-900, 632.8, 638, 655, 670, 755, 1550 nm
- Session Duration
- 20 seconds, 15 minutes
- Session Frequency
- 3 per week
- Therapy Duration
- 182 days
- Study Scope
- Androgenetic Alopecia
Study Title: Utilizing electromagnetic radiation for hair growth: a critical review of phototrichogenesis.
Partial Hair Regrowth Reported After Amber-to-Infrared Light for Spot Baldness
15 adults with spot baldness took part in a 2003 clinical trial testing a linear polarized light device for hair regrowth. Participants received light spanning 600 to 1600 nm, from amber through infrared, applied to the scalp for 3 minutes per session, once a week or every 2 weeks, over 24 to 150 days of treatment. 7 of 15 treated areas (46.7%) showed hair regrowth about 1.6 months earlier than untreated areas, a difference that appeared to be statistically significant. 1 patient reported a sensation of heat in the treated area during the study.
- Study Type
- Clinical Trial
- Participants
- 15
- Treated Area
- Head
- Wavelength(s)
- 600-1600 nm
- Distance
- Contact
- Session Duration
- 3 minutes
- Session Frequency
- 1-14 per week
- Therapy Duration
- 24-150 days
Study Title: Linear polarized infrared irradiation using Super Lizer is an effective treatment for multiple-type alopecia areata.
The CURE Index (Clinical Understanding of Red-light Evidence) by Helio Cure is a 0-100 evidence score based on published human clinical trials. Higher scores mean stronger evidence. Read full methodology →
Data is powered by AI and reviewed by the Helio Cure team.
This page is for educational purposes only. Not medical advice. Consult a healthcare provider before starting red light therapy. Helio Cure does not diagnose, treat, or cure any medical condition.
Last updated: Aug 10, 2026