Table 2.

Adverse effects of repeated low-level red light therapy group study

Study	Adverse effects
Yu Jiang, 2019	Six participants stopped the RLRL treatment, two of whom stopped due to “feeling the light was too bright”
Lei Tian, 2021	No significant side effects were observed in the short term
Yanxian Chen, 2020	No serious adverse events were reported during the 12-month follow-up period
Jing Dong, 2019	Thirteen participants reported a total of 18 adverse events, but the data safety monitoring committee concluded that none of them were related to the light therapy. In the RLRL group, there was one case each of influenza, eyelid injury requiring surgical repair, and acute mesenteric lymphadenitis; two cases each of earwax blockage and allergic rhinitis; and three cases of dental caries
Yi Yan, 2019	No eye complications such as photophobia, tearing, corneal epithelial damage, cataracts, or macular damage were observed after intervention in the RLRL group

RLRL=repeated low-level red light