Is It Safe? The Evidence on Safety
General Safety Profile
Across published literature, no clinically significant adverse events have been reported from photobiomodulation therapy when used within established clinical parameters. Mild, transient side effects may include cutaneous irritation, itching, or transient redness at the treatment site, and these are not associated with any rise in target tissue temperature.[13][3][^4]
A 2026 systematic review of 23 RCTs in geriatric orofacial patients explicitly concluded: "No clinically significant adverse events were reported". A 2026 systematic review of chronic pain across 14 RCTs similarly confirmed "the incidence of adverse events was low, reinforcing the method's safety".[25][13]
Eye Safety
Direct ocular irradiation with LED devices at clinical parameters carry minimal ocular risk and may be beneficial in some ocular conditions when applied through closed eyelids)[^27]
Oncologic Safety
Given that PBM stimulates cell proliferation and influences metabolic pathways, concerns about potential tumor promotion have been raised and rigorously investigated.[26][20]
A 2020 systematic review of 67 studies (43 in vitro, 15 in vivo, 9 clinical) concluded:[^23]
"In vivo studies and clinical trials demonstrate that PBMT is safe with regards to tumor growth... Current human studies show safety with PBMT using currently recommended clinical parameters."
A 2023 systematic review specifically addressing oncologic safety for aesthetic skin rejuvenation found:[20][26]
Within established parameters, PBM does not induce dysplastic change in healthy cells
PBM mainly reduces neoplastic cell proliferation and viability, or makes no difference
"There are no relevant clinical trial data linking PBM with any significant adverse events, including a new or recurrent malignancy"
Contraindications and Precautions
Published clinical guidance identifies the following contraindications and relative precautions:[27][3]
Absolute Contraindications:
Known or suspected malignant lesions in the treatment field (except for cancer therapy-related side effects with physician permission)[^27]
Relative Contraindications / Precautions:
Pregnancy: No evidence of fetal harm, but no safety data either; avoid direct irradiation over the developing fetus[3][27]
Thyroid: Avoid high-intensity direct irradiation over the thyroid gland; LED devices at clinical parameters are lower risk[^27]
Tattoos: Pigments may absorb energy and cause localized heating/pain; treat at distance if symptomatic[^27]
Very dark skin (Fitzpatrick V–VI): Higher melanin content may cause uncomfortable heating with high-irradiance laser devices; use non-contact technique or reduce irradiance[^27]
Important clinical check before treatment: Before treating acute or chronic pain with PBMT, the provider must confirm the diagnosis is from a neuromusculoskeletal condition caused by aging or injury and that there is no disqualifying condition.[^3]
