It is known that users of psychotropic drugs often have weight gain, adverse eﬀects on bone mineral density and osteoporosis, but the molecular basis for these side eﬀects is poorly understood. The aim of this study is to evaluate the eﬀects in vitro of duloxetine (a serotonin and norepinephrine reuptake inhibitor) and ﬂuoxetine (a selective serotonin reuptake inhibitor) on the physiology of human adult stem cells. Adipose-derived stem cells (ADSCs) were isolated and characterized investigating phenotype morphology, expression and frequency of surface markers. Then, a non-toxic concentration of duloxetine and ﬂuoxetine was selected to treat cells during adipogenic and osteogenic diﬀerentiation. Stemness properties and the diﬀerentiation potential of drug-treated cells were investigated by the quantiﬁcation of adipogenic and osteogenic markers gene expression and histological staining. The collected data showed that the administration of a daily non-toxic dose of duloxetine and ﬂuoxetine has not directly inﬂuenced ADSCs proliferation and their stemness properties. The treatment with duloxetine or ﬂuoxetine did not lead to morphological alterations during adipogenic or osteogenic commitment. However, treatments with the antidepressant showed a slight diﬀerence in adipogenic gene expression timing. Furthermore, duloxetine treatment caused an advance in gene expression of early and late osteogenic markers. Fluoxetine instead caused an increase in expression of osteogenic genes compared to untreated cells. In contrast, inpre-diﬀerentiatedcells,thedailytreatment withduloxetine or ﬂuoxetinedidnotaltertheexpressionproﬁleof adipogenic and osteogenic diﬀerentiation. In conclusion, a non-toxic concentration of duloxetine and ﬂuoxetine does not alter the stemness properties of ADSCs and does not prevent the commitment of pre-diﬀerentiated ADSCs in adipocytes or osteocyte. Probably, the weight gain and osteoporotic eﬀects associated with the use of psychotropic drugs could be closely related to the direct action of serotonin.