Fatal Outcome Following Polysubstance Use: A Case Report of Rhabdomyolysis, Acute Kidney Injury, and Deep Vein Thrombosis

Background: Polysubstance use, particularly the combination of opioids and stimulants, represents a growing public health concern due to its high risk of severe multisystem complications and mortality. Here, we present a case illustrating the lethal synergy of opioid–stimulant co-use. Methods: A 37-year-old male with chronic Hepatitis C and documented polysubstance use reported recent use of fentanyl, cocaine, methamphetamine, and cannabis. He presented with generalized weakness, left lower limb pain, tense edema, and anuria. Clinical assessment included monitoring of vital signs, physical examination, capillary blood gas analysis, extended laboratory panels (muscle and cardiac enzymes, electrolytes, and coagulation parameters), urinalysis, and Doppler imaging. Management over five days included intravenous hydration, diuretics, urinary alkalinization, electrolyte correction, anticoagulation, metabolic and vitamin therapy, hemodialysis, and comprehensive supportive care. Results: Laboratory evaluation revealed massive rhabdomyolysis (peak CK 161,050 U/L), severe hyperkalemia (K+ 8.4 mmol/L), metabolic acidosis, acute kidney injury with oligoanuria, and left-sided deep vein thrombosis. Despite intensive multidisciplinary interventions, the patient’s repeated refusal of ongoing treatment critically contributed to a fatal outcome. Conclusions: This case underscores the high mortality risk associated with opioid–stimulant co-use and the crucial impact of treatment refusal. Clinicians and public health stakeholders should recognize the rapid progression of multisystem dysfunction in polysubstance users and prioritize early, aggressive interventions combined with patient engagement strategies to mitigate fatal outcomes.