In a case of substance intoxication characterized by agitation and visual hallucinations, which substance is likely involved?

The presence of agitation and visual hallucinations in a case of substance intoxication is most commonly associated with methamphetamines. Methamphetamines are powerful central nervous system stimulants that can lead to significant psychological effects, including increased agitation and acute episodes of hallucinations.

The neurochemical impact of methamphetamines can cause excessive release of neurotransmitters like dopamine, which plays a role in mood regulation and perception. This hyperstimulation often leads to symptoms such as heightened energy levels, extreme agitation, and, notably, visual or auditory hallucinations.

While other substances like cocaine might also lead to similar symptoms, the specific combination of agitation and visual hallucinations is more frequently noted with methamphetamine use. Alcohol typically results in sedation and can also cause hallucinations during withdrawal rather than intoxication. Heroin, being an opioid, usually induces relaxation and may not manifest these particular psychological symptoms to the same extent.

Thus, considering the characteristics of the symptoms described, methamphetamines are the substance that aligns most closely with the scenario presented.