This study aims to investigate the effect of Epstein-Barr virus (EBV) reactivation or EBV reactivation with dexamethasone (DXM) in patients with adverse drug reactions (ADRs) through evaluating the levels of monocyte, macrophage M2/M1, and cytokines, and investigating whether expression of EBV receptor EphA2 could specifically influence EBV activation in ADRs. We performed a prospective longitudinal study to analyze the monocytes, macrophages, M2/M1 ratio, and cytokines, including interleukin (IL)-4, IL-13, tumor necrosis factor (TNF)-alpha, interferon (IFN)-gamma, IFN-beta, C-X-C motif chemokine ligand (CXCL)9, and CXCL10, in patients with maculopapular exanthema (MPE) and Stevens-Johnson syndrome/toxic epidermal necrolysis (SJS/TEN), and control groups after disease onset. Skin biopsy samples from these patients were subjected to hematoxylin and eosin (H&E) staining to examine tissue architecture and inflammatory cell infiltration, as well as Epstein-Barr virus-encoded RNA (EBER) staining to detect the presence of EBV within the skin lesions. Peripheral blood mononuclear cells collected from these patients were co-cultured with EBV or EBV combined with DXM to assess the impact on monocytes, macrophages, the M2/M1 ratio, and the associated cytokine profile. Furthermore, we sought to identify which cytokines might be crucial in mediating the interaction between the M2/M1 ratio and EBV. EPhA2 expression was evaluated to determine its role in the reactivation of EBV and its correlation with increased viral load in MPE and SJS/TEN patients. Selective depletion of macrophages occurred during the acute stage of SJS/TEN, while a shift towards M2 macrophages was observed in MPE. Both IFN-beta and CXCL9 levels were elevated in MPE and SJS/TEN. Additionally, our study demonstrated the presence of EBV in the skin lesions of SJS/TEN and MPE patients through H&E and EBER staining, confirming EBV's involvement in these conditions. Activation of EBV and EBV combined with DXM led to a shift from M1 to M2 macrophages, accompanied by increased levels of IL-4, IFN-gamma, and CXCL9 in MPE and SJS/TEN, compared to healthy individuals. Specifically, EBV combined with DXM primarily drove IFN-gamma and IL-4 expansions in MPE, while CXCL9 was predominantly elevated in SJS/TEN. The increased IL-4 levels were associated with the relative rise in EBV viral loads after EBV combined with DXM stimulation. Furthermore, EphA2 expression in monocytes was significantly higher in SJS/TEN and MPE patients compared to controls, with further increases on EBV stimulation. This elevation in EPhA2 correlated with increased EBV viral load, particularly in MPE and SJS/TEN patients. The gradual shift from M1 to M2 cell development observed during the clinical course of MPE and SJS/TEN is mediated by the predominance of EBV and EBV with DXM at the acute stage, leading to elevated IL-4, IFN-gamma, and CXCL9 levels, which may exacerbate allergic reactions. The elevation in EPhA2 correlated with increased EBV viral load, particularly in MPE and SJS/TEN patients, suggesting that adverse drug reactions may induce EPhA2 expression, facilitating EBV replication and activation. EphA2 could thus serve as an indicator of EBV activation and a marker for assessing the risk of EBV in patients with adverse drug reactions.