Comparison of photobiomodulation therapy with conventional treatment in patients with herpes labialis: a systematic review and meta-analysis of randomized controlled trials

Herpes labialis (HL) is a common viral infection of the lips, primarily caused by herpes simplex virus type1. Although conventional treatment for HL primarily consist of antiviral agents, photobiomodulation therapy (PBMT) has also emerged as an effective intervention. This study aims to compare PBMT with conventional treatment for HL. A systematic review of randomized controlled trials (RCTs) was conducted through Cochrane Library, PubMed, Semantic Scholar, Dimension AI and Web of Science in accordance to PRISMA guidelines. English language RCTs reporting comparison of PBMT with conventional treatment (i.e., acyclovir, valacyclovir, and penciclovir) in HL were eligible, without restriction on patient’s age and publication year. The primary outcomes were pain (on visual analog scale: VAS), healing time (in days) and HL lesion size (in cm²). Cochrane’s Risk of Bias (RoB) 2.0 tool and RevMan 5.0 was used for quality appraisal and conducting meta-analysis of the selected RCTs, respectively. Six RCTs involving ²60 HL patients (PBMT: 129, conventional treatment: 131) were included. Pain score at day 2 and 3 after treatment showed an overall effect favoring the PBMT with a standardized mean difference (SMD) of [-1.54 (95% CI: -2.32 to -0.77; Z = 3.92, p < 0.001] and [-0.88 (95% CI: -1.19 to -0.57; Z = 5.62, p < 0.001], respectively. The pooled data revealed that PBMT resulted in significantly faster healing of the HL lesions [1.22 days (95% CI: -1.93 to -0.51; p = 0.0007). At day 3 after treatment, a significantly higher decrease in the lesion size was observed for patients receiving PBMT compared conventional treatment [-0.99 cm² (95% CI: -1.41 to -057; p < 0.0001)]. The overall RoB score for 05 RCTs revealed High risk of bias, primarily arising from domain 5 of the RoB 2.0 tool. PBMT demonstrated significant reduction in pain, healing time and lesion size, as compared to conventional treatment, though smaller number of available RCTs warrants further investigation.