Patients suffering from major depression and related pathologies (feeding and eating disorders, obsessive-compulsive disorder, post-traumatic stress disorder, anxiety disorders, etc.) are usually treated with antidepressant agents belonging to several pharmacological and chemical classes; the most recent of these agents are collectively known as "new-generation antidepressants". In these patients, therapeutic drug monitoring (TDM) with the determination of drug and metabolite blood levels is one of the most useful procedures to optimise and personalise the treatment, enhancing both effectiveness and safety. A new approach is proposed in this study, based on microsampling of both blood and oral fluid by means of volumetric absorptive microsampling (VAMS). This approach makes sampling and storage much simpler and even self- and at-home-sampling possible, while retaining reliability, vastly increasing analyte stability and reducing overall expenses. The microsamples were pretreated by means of microextraction by packed sorbent (MEPS) on C2 sorbent and analysed by liquid chromatography with sequential spectrophotometric and spectrofluorimetric detection (HPLC-UV-FL). Method validation results were satisfactory (extraction yield >84%, precision RSD < 8.9%, stability>85.0% after 3 months). Application to blood and oral fluid VAMS from patients treated with four possible different antidepressants (sertraline, fluoxetine, citalopram and vortioxetine) provided results always in good agreement with those obtained from the corresponding fluid matrices, including the levels of drug metabolites.