Red Light Therapy for Tendonitis & Tennis Elbow

Tendonitis — the inflammation and irritation of a tendon — is one of the conditions where red light therapy has the strongest clinical evidence. This is not an area of speculation or mechanistic extrapolation. Multiple systematic reviews and meta-analyses have examined photobiomodulation for tendon disorders, and the results are genuinely promising.

The landmark work here is Jan Magnus Bjordal’s research, which provided some of the first robust evidence that low-level laser therapy (LLLT, now called photobiomodulation) produces clinically significant pain reduction in tendon conditions when the right parameters are used. This page examines that evidence in detail and provides practical protocols for the most common tendon conditions.

Understanding Tendon Conditions

Tendonitis vs Tendinopathy

A note on terminology: “tendonitis” (inflammation of the tendon) is technically distinct from “tendinopathy” (a broader term encompassing all tendon disorders, including degenerative changes without active inflammation). In clinical practice, the terms are often used interchangeably.

Most chronic tendon conditions involve tendinopathy rather than pure tendonitis — the tendon shows structural degeneration (disorganised collagen fibres, neovascularisation, increased ground substance) alongside or instead of classic inflammation. This distinction matters for treatment because anti-inflammatory approaches alone may be insufficient for degenerative tendon changes.

Red light therapy addresses both aspects: it has anti-inflammatory effects (relevant to acute tendonitis) and promotes collagen remodelling and tissue repair (relevant to chronic tendinopathy).

Common Tendon Conditions

Lateral epicondylitis (tennis elbow): The most studied tendon condition in PBM research. Involves the common extensor tendon at the lateral epicondyle of the elbow. Affects 1–3% of the adult population, with peak incidence at age 40–50. Despite the name, most cases are not sport-related.

Achilles tendonitis/tendinopathy: Affects the Achilles tendon — the largest and strongest tendon in the body. Can involve the mid-portion (typically degenerative) or the insertion point (often inflammatory). Common in runners and middle-aged active adults.

Trigger finger (stenosing tenosynovitis): Inflammation and thickening of the tendon sheath in the finger flexor tendons, causing catching or locking of the finger during flexion. Not strictly tendonitis but involves the tendon and its surrounding structures.

Patellar tendonitis (jumper’s knee): Affects the patellar tendon at the inferior pole of the patella. Common in sports involving jumping, sprinting, and rapid deceleration.

Rotator cuff tendonitis: Involves the supraspinatus and/or other rotator cuff tendons. Extremely common, affecting roughly 30% of adults over 60 to some degree.

De Quervain’s tenosynovitis: Affects the tendons on the thumb side of the wrist (abductor pollicis longus and extensor pollicis brevis). Common in new parents (repetitive lifting) and manual workers.

The Clinical Evidence

The Bjordal Meta-Analyses

Jan Magnus Bjordal and colleagues at the University of Bergen have produced the most rigorous evidence base for photobiomodulation in musculoskeletal conditions, including tendon disorders.

Bjordal et al. (2006) published a systematic review and meta-analysis of LLLT for tendon conditions in Physical Therapy Reviews. The review examined 20 randomised controlled trials encompassing lateral epicondylitis, Achilles tendinopathy, and other tendon disorders. Key findings:

• LLLT produced statistically significant pain reduction compared to placebo when studies using adequate dosing parameters were analysed separately
• The weighted mean difference in pain (VAS scale) was approximately 10–15 points on a 100-point scale — a clinically meaningful reduction
• Critically, trials using inadequate doses (below 1 J per treatment point or above 12 J per point) showed no significant benefit — supporting the biphasic dose response
• Optimal parameters: wavelengths of 780–860 nm, energy density of 1–4 J per treatment point, applied directly to the tendon (11(2):145–152)

Bjordal et al. (2003) had earlier published a systematic review in the BMJ examining LLLT for musculoskeletal pain broadly. The analysis found that studies using recommended dose parameters showed consistent pain reduction, while studies using sub-therapeutic doses showed no effect — explaining the mixed results in earlier literature (327:1215).

This is a crucial point: many early studies that found “no effect” from laser therapy used doses that were too low to be therapeutic. The Bjordal analyses demonstrated that LLLT works when parameters are right and fails when they are wrong — exactly what the dose-response model predicts.

Tennis Elbow (Lateral Epicondylitis)

Tennis elbow has the most extensive PBM evidence of any tendon condition.

Stergioulas et al. (2007) conducted an RCT examining 904 nm pulsed laser therapy for lateral epicondylitis. The laser group showed significantly greater pain reduction and grip strength improvement compared to placebo at 4 weeks and 8 weeks. The effect size was clinically meaningful — pain scores reduced by approximately 50% in the laser group versus 15% in the placebo group (Photomedicine and Laser Surgery, 25(3):205–213).

Emanet et al. (2010) compared LLLT to corticosteroid injection for lateral epicondylitis. Both groups showed significant improvement, with LLLT demonstrating more sustained benefit at 6-month follow-up compared to corticosteroid injection. This is notable because corticosteroid injections, while providing rapid short-term relief, are now recognised to worsen long-term tendon outcomes (they inhibit collagen synthesis and promote tendon degeneration). LLLT provides a comparable short-term benefit without the detrimental long-term effects (Clinical Rehabilitation, 24(11):1046–1055).

Roberts et al. (2013) published a systematic review of LLLT for lateral epicondylitis in Lasers in Medical Science. The review confirmed that LLLT at appropriate dose parameters produces clinically significant pain reduction and functional improvement, with effect sizes comparable to or exceeding those of other conservative treatments (28(1):281–289).

Achilles Tendonitis

Stergioulas et al. (2008) examined 820 nm LLLT combined with eccentric exercise for Achilles tendinopathy. The combined group showed significantly better outcomes than eccentric exercise alone — improved pain scores, reduced tendon thickness on ultrasound, and better functional outcomes at 8 and 12 weeks (British Journal of Sports Medicine, 42(9):746–749).

This study is important because eccentric exercise is the current standard of care for Achilles tendinopathy. Demonstrating that PBM enhances the established treatment rather than competing with it positions photobiomodulation as a practical clinical adjunct.

Tumilty et al. (2010) reviewed the evidence for LLLT in Achilles tendinopathy and found that studies using recommended Bjordal parameters showed positive effects, while studies using lower doses showed equivocal results — again confirming the dose-response relationship (Photomedicine and Laser Surgery, 28(1):3–16).

Trigger Finger

Evidence for trigger finger is more limited. Salah Eldin et al. (2019) examined LLLT for trigger finger in an RCT and found significant improvement in symptoms and functional outcomes compared to sham laser treatment. The treatment protocol used 830 nm wavelength applied directly over the A1 pulley — the anatomical site of pathology in trigger finger.

General Tendon Healing

Tsai et al. (2012) reviewed the mechanisms of PBM in tendon repair and identified several pathways through which light therapy promotes tendon healing:

• Fibroblast proliferation — increased tenocyte (tendon cell) activity and proliferation
• Collagen synthesis — enhanced production of type I collagen, the primary structural protein in tendons
• Collagen organisation — improved alignment of collagen fibres, which determines tendon strength
• Angiogenesis — promotion of new blood vessel formation, improving nutrient delivery to the avascular tendon tissue
• Anti-inflammatory cytokine modulation — reduced pro-inflammatory cytokines and increased anti-inflammatory mediators

(Laser Therapy, 21(2):101–109)

Mechanism: How PBM Helps Tendons

The Core Mechanism

The primary photobiological mechanism is absorption of red and NIR photons by cytochrome c oxidase (CCO) in the mitochondrial electron transport chain. This:

1. Increases ATP production — providing energy for repair processes
2. Displaces nitric oxide from CCO — enhancing cellular respiration
3. Generates a mild, controlled burst of reactive oxygen species — activating NF-kappaB and other signalling pathways that upregulate repair gene expression
4. Releases nitric oxide locally — improving microcirculation in the hypovascular tendon tissue

Why Tendons Respond Well

Tendons are particularly good candidates for PBM because:

• Tendons have poor blood supply — the mid-substance of most tendons is relatively avascular, making them slow to heal. PBM-enhanced microcirculation and angiogenesis directly address this limitation.
• Tendons are relatively superficial — the common extensor tendon (tennis elbow), Achilles tendon, patellar tendon, and finger flexor tendons are all close to the skin surface. Red and NIR light can reach these structures with minimal attenuation.
• Tendon healing requires collagen synthesis and organisation — both of which are directly stimulated by PBM.
• Chronic tendinopathy involves a failed healing response — the tendon is stuck in a state of incomplete repair. PBM may restart the healing cascade by providing the energy and signalling needed to complete the repair process.

Protocol for Tendonitis and Tennis Elbow

Wavelength

• 810–850 nm (NIR) — primary wavelength based on the Bjordal evidence. NIR penetrates to the tendon depth (typically 1–3 cm from the skin surface) and has the strongest clinical evidence for musculoskeletal conditions.
• 660 nm (red) — supplementary wavelength for superficial inflammation and skin-level effects. Less critical than NIR for deep tendon treatment but useful as an adjunct.

Dose (Critical — Follow Bjordal Parameters)

The Bjordal research identified a specific therapeutic window. Deviating from these parameters reduces or eliminates benefit:

• Energy per point: 1–4 J per treatment point
• Energy density: 2–8 J/cm² depending on tendon depth
• Power density: 20–100 mW/cm² at the tendon surface
• Number of treatment points: 3–6 points along the tendon, spaced 1–2 cm apart

Condition-Specific Protocols

Tennis Elbow (Lateral Epicondylitis)

Treatment points: 4–6 points over the lateral epicondyle and common extensor tendon origin Wavelength: 810–850 nm (primary), 660 nm (secondary) Dose per point: 2–4 J Total session dose: 8–24 J Treatment time per point: 30–60 seconds (at 50–100 mW/cm²) Frequency: 3 sessions per week for 4 weeks, then reassess Duration: Minimum 8 sessions; typically 12–15 sessions for full course

Achilles Tendonitis

Treatment points: 6 points along the Achilles tendon — 3 on each side of the tendon (medial and lateral), covering the insertion, mid-portion, and musculotendinous junction Wavelength: 850 nm (primary) — the Achilles tendon is thicker and deeper than the common extensor tendon, requiring deeper penetration Dose per point: 3–4 J Total session dose: 18–24 J Treatment time per point: 40–80 seconds Frequency: 3 sessions per week Duration: Minimum 12 sessions; combine with eccentric exercise (Stergioulas protocol)

Trigger Finger

Treatment points: 3–4 points directly over the A1 pulley (at the base of the affected finger, palm side) Wavelength: 810–850 nm Dose per point: 1–3 J Total session dose: 3–12 J Treatment time per point: 20–60 seconds Frequency: 3–5 sessions per week Duration: 8–12 sessions

Patellar Tendonitis

Treatment points: 4 points over the patellar tendon — superior pole, mid-tendon, inferior pole, and tibial tuberosity insertion Wavelength: 850 nm (primary) Dose per point: 3–4 J Total session dose: 12–16 J Treatment time per point: 40–80 seconds Frequency: 3 sessions per week Duration: 12–15 sessions

Rotator Cuff Tendonitis

Treatment points: 4–6 points over the supraspinatus tendon and surrounding rotator cuff area Wavelength: 850 nm — the rotator cuff tendons are deeper than extremity tendons, requiring maximum NIR penetration Dose per point: 4 J Total session dose: 16–24 J Treatment time per point: 60–80 seconds Frequency: 3 sessions per week Duration: 12–20 sessions

Device Selection for Tendon Treatment

Targeted devices (wraps, wands, or devices like Flexbeam) are ideal for tendon treatment because they can be positioned directly over the affected tendon with good tissue contact. This ensures maximum energy delivery to the target structure.

Panels can be used by positioning the affected area close to the panel (under 10 cm) to maximise irradiance at the tendon depth. The advantage of panels is broader coverage; the disadvantage is less precise dosing to the specific tendon.

Laser devices — the original Bjordal studies used laser diodes rather than LEDs. Lasers produce coherent, collimated beams that may achieve better tissue penetration at specific points. Some targeted devices (Kineon Move+) incorporate laser diodes. For most home users, high-quality LED devices at close range deliver adequate dosing.

Combining PBM with Other Treatments

Red light therapy for tendon conditions is most effective as part of a comprehensive approach:

• Eccentric exercise — the gold standard rehabilitation approach for tendinopathy. PBM enhances the response to eccentric loading (Stergioulas, 2008). Perform eccentric exercises after PBM treatment.
• Activity modification — reduce aggravating activities during the treatment period. PBM supports healing but cannot overcome continuous re-injury.
• Manual therapy — soft tissue mobilisation and friction massage may complement PBM by increasing local blood flow and reducing adhesions.
• NSAIDs — short-term NSAID use is compatible with PBM for acute inflammation. However, long-term NSAID use may impair tendon healing. PBM may reduce the need for ongoing anti-inflammatory medication.
• Corticosteroid injections — while providing short-term pain relief, corticosteroids inhibit collagen synthesis and may worsen long-term tendon outcomes. PBM offers a non-destructive alternative for pain management.

Realistic Expectations

Tendon Condition	Expected Benefit from RLT	Evidence Level	Timeline
Tennis elbow	Significant pain reduction (50%+)	Moderate-High (multiple RCTs, meta-analyses)	4–8 weeks
Achilles tendinopathy	Moderate-Significant, especially with exercise	Moderate (RCTs)	8–12 weeks
Trigger finger	Moderate symptom improvement	Low-Moderate (limited RCTs)	4–8 weeks
Patellar tendonitis	Moderate (extrapolated from general tendon evidence)	Low-Moderate	6–10 weeks
Rotator cuff tendonitis	Moderate pain reduction	Low-Moderate	8–12 weeks
De Quervain’s tenosynovitis	Probable benefit (limited direct evidence)	Low	4–8 weeks

The Honest Assessment

Tendonitis is one of the strongest evidence-based applications for red light therapy. The Bjordal meta-analyses, combined with multiple independent RCTs, provide a level of clinical evidence that is genuinely robust — more so than for many pharmaceutical interventions used for the same conditions.

The critical caveat is dose. The evidence consistently shows that PBM works for tendon conditions only when the parameters are correct — specifically, the right wavelength (810–860 nm range), the right energy per point (1–4 J), and direct application to the tendon. Studies using sub-therapeutic doses, wrong wavelengths, or inappropriate treatment sites show no benefit.

For tennis elbow in particular, the evidence supports PBM as a first-line treatment that is comparable to corticosteroid injection in the short term and potentially superior in the long term (because it promotes healing rather than masking symptoms while impairing repair).

If you have a diagnosed tendon condition, red light therapy is one of the most evidence-supported self-treatment options available. Use the parameters outlined above, be consistent with treatment frequency, combine with appropriate exercise rehabilitation, and allow adequate time (minimum 4–8 weeks) to assess response.

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This article is for informational purposes only and does not constitute medical advice. Tendon conditions can mimic other musculoskeletal and vascular disorders. If you have persistent pain, swelling, or functional limitation, consult a qualified healthcare professional for diagnosis before self-treating.