Xerostomia, a common side effect of radiotherapy, can significantly impact patients' quality of life. This study aimed to compare the immediate effects of infrared light photobiomodulation on salivary flow and pH in individuals experiencing xerostomia. Twenty adults with xerostomia participated in the study, divided into two groups: Group 1 (G1) received extraoral photobiomodulation treatment, and Group 2 (G2) received both intra and extraoral treatment. Stimulated saliva was collected before and immediately after light application. In G1, the photobiomodulation was applied using a cluster (808 nm, 120 mW, 24J), while G2 received treatment with a pointer (808 nm, 100mW, 6J per point). The results confirmed our hypothesis, showing a statistically significant increase in immediate salivary flow stimulation with the headgear technique (G1) (p= 0.037). Analyzing the percentage of volume variation (ml) per minute, the average salivary flow increased from 0.86 ml/min to 1.2 ml/min after extraoral application with an infrared laser cluster, representing a 7% increase. In conclusion, the protocol involving only extraoral application was effective in stimulating salivary flow. Further research is needed to understand the specific mechanisms behind these differences and optimize photobiomodulation techniques for xerostomia management. This study found that using external infrared photobiomodulation can immediately increase salivary flow in xerostomia patients, potentially offering a comfortable and effective symptom management method. It emphasizes the need for refining these techniques and further research to understand long-term effectiveness.