Umbrella review of low-level light therapy: evidence across clinical conditions.
Eunhye Song, Lin Ang, Mi Hong Yim et al.
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In 30 seconds
This umbrella review synthesized systematic reviews and meta-analyses of low-level light therapy (LLLT) in humans across clinical conditions. It included 100 reviews, covering 790 unique primary studies. Overall, 62 reviews favored the evaluated intervention, 34 reported neutral or mixed conclusions, and 4 were unclear; favorable conclusions were most common for oncology-related complications. However, most reviews had low or critically low methodological confidence, and adverse-event reporting was incomplete. The authors conclude that these descriptive findings suggest potential benefit in selected indications but do not establish efficacy or safety.
Key findings
- Of 100 reviews, 62 favored the evaluated intervention, 34 reported neutral or mixed conclusions, and 4 had unclear conclusions.
- The evidence base included 53 reviews of oral and dental conditions and 22 of musculoskeletal disorders.
- AMSTAR 2 ratings were low for 30.0% of reviews and critically low for 60.0%.
- Eleven reviews reported adverse events, 32 explicitly reported none, and 57 provided no adverse-event information.
Why it matters
The review maps a broad and fragmented literature, indicating that conclusions about LLLT vary across conditions and that favorable findings are not equivalent to reliable evidence of efficacy. Low methodological confidence and gaps in safety reporting make it difficult to judge the balance of benefit and harm, underscoring the need to interpret condition-specific claims cautiously.
What to keep in mind
Most included reviews had low or critically low methodological confidence. Treatment parameters varied, and adverse-event information was absent from many reviews, limiting interpretation of efficacy and safety.