Safety is a reasonable first question for anyone considering photobiomodulation for neck pain. The cervical spine houses the spinal cord, major blood vessels, and the nerve roots that control arm and hand function, so any therapy applied there deserves a careful safety look. Across the neck pain literature the picture is consistent: photobiomodulation carries minimal risk, with side effects that are rare and mild when they occur, and a profile that compares favorably with the standard drug-based options for sustained use.
For the complete clinical evidence, see PBM for Neck Pain: Clinical Evidence. For how the therapy works and the wavelengths involved, see Red Light Benefits for Neck Pain and Infrared Light Benefits for Neck Pain. For the overview, see Red Light Therapy for Neck Pain: Scientific Research Review.
Key Takeaways
- No serious adverse events reported in neck-pain trials: Across the Lancet meta-analysis (16 RCTs, 820 participants) and the neck-pain RCTs reviewed, no serious adverse events were attributed to photobiomodulation.
- Side effects rare and mild: In the Lancet meta-analysis, side effects were mild and no different from placebo: occasional tiredness, headache, or brief temporary pain increase, all self-resolving.
- A chronic-pain review that tracked adverse events found few: A 2026 systematic review that assessed adverse events as a formal outcome across chronic-pain RCTs reported a low incidence, mostly transient local warmth or mild discomfort.
- Compatible with standard care: Photobiomodulation has been used alongside anti-inflammatories, muscle relaxants, exercise, manual therapy, and TENS in trials without documented adverse interactions.
- Favorable for sustained use: Unlike NSAIDs (stomach, heart, and kidney risks), cortisone injections (declining effect and tissue risk with repetition), and muscle relaxants (sedation), photobiomodulation carries no systemic drug risks, which matters for a condition often managed over months.
For a non-drug treatment, the safety question is about as well-settled as it gets. Hundreds of RCTs, an umbrella review north of 9,000 participants, no serious adverse events. The Lancet analysis tracked side effects across 16 neck pain trials and the worst it turned up was occasional tiredness. What that buys a patient is real: they can use it daily without worrying about GI bleeding, cardiac risk, or the grogginess that comes with muscle relaxants. Most of my standard options can't say that.— Dr. William Carter, MD
What the Reviews and Trials Report
The strongest direct safety data comes from the trials that actually tracked side effects. The 2009 Lancet meta-analysis (Chow et al.) assessed adverse events across its 16 RCTs and found side effects were mild and not different from placebo. The reported effects were tiredness, nausea, headache, or a brief increase in pain, and the only statistically significant difference between laser and control across all trials was increased tiredness in a single study. About half the trials did not report side-effect data at all, which is a limitation of reporting rather than evidence of harm.
A 2026 systematic review by Ferreira et al. is more useful for safety specifically, because it set out to measure adverse events as a formal secondary outcome across chronic-pain RCTs, including a chronic neck and shoulder pain trial. It found a low incidence of adverse events, with the effects that did appear limited to transient local warmth or mild discomfort at the application site. Cidral-Filho et al. (2024), reviewing 36 clinical studies of photobiomodulation for neck and shoulder conditions, described it as a safe, non-invasive option.
One review is often cited here that should be read carefully. The 2025 umbrella review by Son et al. covered 204 RCTs and more than 9,000 participants across 15 conditions, which is valuable for showing how large and consistent the photobiomodulation evidence base has become. But it was built to measure whether the therapy works, not to catalog its harms, so it shows the breadth of the evidence rather than standing as a formal safety verdict. The safety conclusion here rests on the trials and reviews that actually measured adverse events.
What the Neck-Specific Trials Show
Looking at the neck pain trials individually, the consistent pattern is that where adverse events were tracked, none serious appeared, and that the reporting itself was uneven. Several trials reported no adverse events: Kenareh et al. (2021), Rampazo et al. (2024) (double-blind sham-controlled), Ince et al. (2023) (90 patients over 12 weeks), Momenzadeh et al. (2022) (sham-controlled), Tasca et al. (2023), the Jiang et al. (2025) wearable-LED pilot, and the Labanca et al. (2025) placebo-controlled pilot. Others did not systematically collect adverse-event data, so "no events reported" sometimes reflects limited surveillance rather than active monitoring. The honest summary: no serious adverse events have been attributed to photobiomodulation in any neck-pain trial, and the mild effects that were recorded were transient.
Comparison with Standard Neck Pain Treatments
The safety comparison matters because chronic neck pain often needs sustained treatment, which is exactly where drug-based options accumulate risk.
NSAIDs (ibuprofen, naproxen, diclofenac) work short-term but carry gastrointestinal bleeding, cardiovascular, and kidney risks with sustained use; prescription NSAIDs carry an FDA boxed warning for cardiovascular and GI risk. Muscle relaxants such as cyclobenzaprine cause sedation and dizziness and are generally avoided in older adults. Cortisone injections lose effect with repetition, can weaken tendon and cartilage, and are typically limited to a few per site per year. Opioids carry well-documented addiction, dependence, and respiratory risks, and guidelines generally recommend against them for chronic neck pain.
Photobiomodulation, by contrast, has no systemic drug risk, no organ toxicity, no addiction potential, and no sedation, and its effect does not decline with repeated use. The main caveat is an honest one: long-term controlled data on daily use over years is limited (see below), so "no documented cumulative risk" is the accurate claim rather than a guarantee of none. Even with that caveat, the gap against the drug options for a therapy meant to be used repeatedly is wide.
Contraindications and Precautions
Photobiomodulation is broadly safe, but standard precautions apply. It should not be applied directly over a known cancer, because the effect of light on tumor cell growth is not fully characterized. Protective eyewear should be used to avoid direct exposure to the eyes. Photosensitizing medications may increase skin sensitivity, though no such reactions have been reported in the neck pain literature.
Pregnancy is listed as a precaution in most photobiomodulation guidance, not because harm has been shown, but because safety data in that population is insufficient. People with epilepsy should be cautious with certain pulsed protocols, though no epilepsy-related events have been reported in the literature. Anyone with an implant, an active infection, or a specific medical condition in the treatment area should check with their clinician first.
Limitations of the Safety Evidence
The safety picture is built mostly from RCTs with treatment courses of two to six weeks. Long-term data from continuous daily use over years is not available from controlled trials, though the underlying mechanism (supporting cellular energy and modulating inflammation) does not suggest a cumulative-risk pathway.
Adverse-event reporting is incomplete in many trials; about half the trials in the Lancet meta-analysis did not report side-effect data. That is a reporting-quality limitation, not evidence of hidden harm, but it means the safety read leans on the subset of trials that systematically collected it. There is also no large tracking system for photobiomodulation side effects the way there is for prescription drugs, because as a non-drug treatment it falls under different monitoring rules. The result is a safety record that looks clean and probably is, but rests on a narrower base of careful reporting than the raw trial count suggests.
Conclusion
The safety evidence for photobiomodulation in neck pain is consistent across the available literature. No serious adverse events have been attributed to it in any neck-pain trial. The trials and reviews that specifically tracked adverse events found them rare and mild: transient warmth, brief tiredness, the occasional headache. It can be used alongside standard care without documented adverse interactions. For a condition often managed over months, the absence of the cumulative drug risks that limit NSAIDs, muscle relaxants, and cortisone is a real advantage, tempered honestly by the fact that long-term controlled data is still limited. For how this profile translates into a device worn on the neck, see how CuraYou's ProWave Deep Healing Pad applies red and infrared light to the cervical area, and for the device trade-offs, LED vs. Laser for Neck Pain.
