A broadened clinical spectrum of concomitant complications emerges among the escalating incidence of substance use, particularly within the 'chemsex' context. This case exemplifies the profound neurotoxic repercussions and neurological risk of chemsex in a young HIV-positive male and addresses the multifaceted challenges of such evolving paradigms in substance utilization. After consuming cannabis, poppers, methamphetamine, and cocaine, a 28-year-old HIV-positive male exhibited significant neurological and cognitive impairment. The initial presentation included dysarthria and profound anterograde amnesia. Laboratory findings showed leukocytosis with a PCR of 3mg/dl - elevated cerebrospinal fluid protein levels with no cells. Urine toxicology returned positive for cannabis and amphetamines. A brain CT scan revealed bilateral and symmetrical hippocampi and pale globes hypodensity, indicative of toxic-metabolic encephalopathy. MRI further identified lesions in the globus pallidus, cerebellum, and hippocampi. Following the detection of toxic encephalopathy, Initial neuropsychological was performed screening using the Montreal Cognitive Assessment (MoCA), which highlighted immediate memory deficits. An in-depth neuropsychological assessment conducted 3weeks later included the Wechsler Adult Intelligence Scale-Fourth Edition (WAIS-IV), the Rey Auditory Verbal Learning Test (RAVLT), and tests for visuospatial skills, motor functions, and memory recall. The evaluations revealed pronounced anterograde amnesia, persistent long-term memory inconsistencies, and notable executive function challenges, detailed in Table 1. The detailed analysis of this case underpins the severe neurological consequences that can manifest from heavy substance use. Comprehensive diagnostic evaluations, including neuroimaging and neuropsychological assessments, are crucial in elucidating the full spectrum of substance-induced cognitive impairments. There is an urgent need for enhanced public awareness and preventative measures, especially in the context of chemsex, to bring forth multifaceted health, social, and government implications that modern society must adeptly navigate.