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Background and Importance The clearance of certain drugs may be modified in inflammatory processes and therefore there may be situations of intoxication by certain drugs such as voriconazole.Aim and Objectives To analyse the influence between C-reactive protein (CRP) values and the presence of elevated plasma levels of voriconazole.Material and Methods Observational and retrospective study where voriconazole determinations were collected in patients from June 2021 to June 2023 in a tertiary level hospital. Patients included: patients with voriconazole treatment with a prescribed maintenance dose of 4 (±1) mg/kg/12h. Patients with concomitant pharmacokinetic modifying drugs (enzyme inducers/inhibitors) and with alanine aminotransferase values >110 IU/L were excluded. The plasma concentration of voriconazole was determined by homogeneous enzyme immunoassay. CRP values were collected at the time of voriconazole determination. Statistical analysis: logistic regression test for the odds ratio between inflammation and voriconazole intoxication. ROC curve (defined by AUC and Youden index) to establish the cut-off point of CRP as a criterion for inflammation and Cmin>5 mg/L was considered as voriconazole intoxication. The statistical analyses were assessed with SPSS V25.0.Results The number of total determinations was 164, of which a total of 53 were excluded (22 due to non-compliance with dosing and 31 due to elevated GPT values). The final total number of determinations was 111, with a total of 46 patients, 67% of whom were men and a median age of 78 [18-87] years. The calculated AUC was 0.712 ±0.69 (95% CI: 0.448-0.795), the Youden index was 0.489 and the optimal cut-off point for the CRP value was 78.7 mg/L (sensitivity: 0.691 and specificity: 0.705). The logistic regression test obtained an OR = 6.89 (95% CI: 2.89-25.81).Conclusion and Relevance A CRP value>78.7 mg/L is associated as a risk factor for voriconazole intoxication according to the logistic regression test; provided that they meet the correct dosage, which in our study was 4 (±1) mg/kg/12h, there is no presence of interacting drugs and liver function is preserved.Conflict of Interest No conflict of interest