effects on the treatment, causing side effects. [4,5,8] Given the fluctuations in the interpatient drugs exposures, personalized prescriptions are a promising strategy to maximize the therapeutic drugs effectiveness. [3,5] Of special importance in recent years, "precision medicine" has been proposed as a new strategy designed at personalizing the dosage toward enhanced therapeutic efficacy and minimal deleterious drug effects. [3] Therapeutic drug monitoring (TDM) consists in tracking the drug levels in blood and/or plasma, or other bodily biofluids comparable to blood drug concentrations aiming individualized dose-response features of drugs. [3,5,9] Therapeutic studies have been made based on blood analysis for personalized TDM; however, it is nonviable owing to the costs with sampling, collecting, storage, transporting, processing, and analyzing in a centralized and specialized laboratory. [3,5,7] Non-invasive bodily biofluids such as sweat, [10] tears, [11] interstitial fluid, [12] breath [13] and saliva [11] are excellent alternatives to be used instead of invasive TDM. [5] Of particular importance, saliva emerges as a valuable biological fluid for TDM purpose offering advantages such as: i) reflects the free analyte levels; ii) saliva is easier to collect than blood without patient stimulation; and iii) patients prefer saliva sampling over blood sampling. Moreover, the analytical tools can be easily designed for analysis of saliva specimens. [6,14,15] Several analytical techniques have been used to analyze the concentration of drugs in TDM. However, these techniques rely on costly and bulky instruments as such as high-performance liquid chromatography (HPLC) that is unsuitable for decentralized analysis requiring skilled personnel. [5,6,15] Saliva-based electrochemical sensors have paved the way for on-site TDM by tracking drug concentrations. [3] Sensors and biosensors have been used to detect Vitamin C, [11] antibiotics, [16] Vitamin C and D, [17] irinotecan and doxorubicin, [18] and Levodopa. [7] With biosensors, high specificity can be achieved; however, the issues with storage, stability, and high cost with enzymes and antibodies remain. Hence, detection of therapeutic drugs for on-site monitoring should be conducted with non-enzymatic sensors [19] in which they can provide costeffective, rapid response, and on-site analysis for TDM. [20] They are more reliable due to high stability, robustness, and Paracetamol or acetaminophen is the main non-opioid analgesic recommended for mild pain by the World Health Organization (WHO) analgesic ladder. However, the high levels used of paracetamol are associated with the hepatotoxicity and nephrotoxicity caused by accumulation of toxic metabolites. The sensor is produced on a polyester substrate containing a full electrochemical device with working, auxiliary, and reference electrodes in which, guiding personalized medicine solutions are not reported. Temporal paracetamol profiles in human saliva are performed with the subject taking different amounts of commercial...