Coronavirus (COVID-19) is a newly emerging zoonotic agent that emerged in December 2019 in China (2019-nCoV) and which results in Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV -2) The scientific literature has made progress in the characterization of the new coronavirus and works extensively on therapies and vaccines against the virus. However, it is now known that SARS-CoV-2 is more than just an acute respiratory syndrome. Long-term COVID-19, or Post-Covid Syndrome or Long-term COVID-19, is a post-viral syndrome that was first reported online in groups of COVID-19 survivors discussing their symptoms after the acute infection has resolved. It begins to gain recognition in the scientific and medical communities. Although a universally accepted definition does not yet exist, reviews have identified that the most frequent symptoms of Lonf-term COVID are fatigue and dyspnea. But two classes of symptoms have been received scientific attention: the musculoskeletal pain and xerostomia. Xerostomia is defined as a subjective sensation of dry mouth described by patients and which is commonly related to hyposalivation (decreased salivary flow rate). The pathophysiology and clinical evolution of xerostomia in COVID-19 still lacks studies, but there are reports of 2 to 30% of patients presenting the complaint of dry mouth sensation even after the resolution of acute COVID. Regular physical therapy, cognitive behavioral therapy have been used and encouraged in the follow-up of patients with post- COVID, demonstrating that even today these practices seem to be more promising than pharmacological treatment. In parallel, studies demonstrate that Photobiomodulation (PBM) therapy is often used for oral diseases and presents itself as a non-invasive, low-cost, safe therapy that has benefits in relation to the quality of life of these patients. PBM refers to a series of therapies in which non-ionizing light beams, including lasers, LEDs and broadband light in the visible and infrared spectra, are used to interact with biological tissues for different purposes. In this sense, this study aims to investigate the clinical effectiveness of the use of a Photobiomodulation protocol in the treatment xerostomia related to Long-Covid. This will be a single-center, randomized, controlled, blind clinical trial that will involve patients with Long-COVID in follow-up at the Medical and Multiprofessional outpatient clinic of University Nove de Julho (UNINOVE). An analysis will be carried out of all medical records of patients who remained hospitalized with COVID-19 at Lydia Storópoli Universitary Hospital during the year 2022 and who were discharged from the inpatient treatment from January to December 2022, for a survey of telephone contact and epidemiological data collection by medical records. All those patients who answer the questions referring to one or more symptoms related to the oral or nasal cavity, which have arisen after the onset of acute COVID infection, will be invited to participate in the study by making a first face-to-face evaluation at the University to confirm the diagnostic criteria of xerostomia, the diagnosis of Long COVID and evaluation of inclusion criteria in the study (adults with COVID-19 with complaints of xerostomia diagnosed more than 4 weeks after the acute infection and persisting for at least 02 months). Pre- and post-treatment evaluations are composed by the Brazilian Version of the SF 36 Quality of Life Scale, salivary sialometry and salivary pH, Oral Health Impact Profile (OHIP-14), Abbreviated Xerostomia Inventory (SXI), Brazilian version of the Functional Independence Measure (FIM), Post -Covid-19 Functional Status Scale and WHO Disability Assessment Scale (WHODAS 2.0) All patients included will be randomized into 2 groups: PBM Group (standard rehabilitation treatment for Long COVID and xerostomia + PBM therapy) or PBM placebo group (standard rehabilitation treatment for Long COVID and xerostomia + placebo PBM therapy). PBM consists of the application of Red LED on the 3 pairs of major salivary glands (parotid, submandibular and sublingual) extraorally, transcutaneously, 3 J/cm2, for 36 seconds, twice a week for 06 weeks. The results will be sent for statistical analysis.