Stimulant Use Disorder

Why Cocaine or amphetamine intoxication is correct

• The picture is a classic sympathomimetic toxidrome: mydriasis, hypertension, tachycardia, hyperthermia, diaphoresis, and agitation
• Tactile/visual hallucinations (formication, "bugs on the walls") are characteristic of stimulant intoxication
• Onset after a recreational party setting fits cocaine or amphetamine use
• Benzodiazepines (lorazepam) are first-line for the agitation, hypertension, tachycardia, and seizure risk
• Avoid beta-blockers alone — unopposed alpha stimulation can worsen hypertension and coronary vasospasm

Why the others are wrong

• Phencyclidine (PCP) intoxication — right-concept-wrong-agent; PCP causes vertical/rotary nystagmus, dissociation, and extreme violence rather than this pure adrenergic surge
• Anticholinergic toxidrome from jimson weed — shares mydriasis, tachycardia, hypertension, and hallucinations, but anticholinergic poisoning produces hot dry flushed skin and urinary retention rather than the diaphoresis described here
• Alcohol withdrawal delirium — overlaps agitation, autonomic hyperactivity, and visual hallucinations, but follows cessation in a physiologically dependent drinker roughly 48-96 hours after the last drink, not acute onset during a party
• Acute opioid withdrawal syndrome — shares mydriasis, tachycardia, diaphoresis, and agitation, but opioid withdrawal leaves the sensorium clear and does not cause visual hallucinations; yawning, rhinorrhea, lacrimation, piloerection, and vomiting or diarrhea would be expected, and it follows cessation in a dependent user rather than arising during a party

Additional high-yield points

• Sympathomimetic vs anticholinergic toxidrome: both cause mydriasis, tachycardia, and hyperthermia, but sympathomimetics produce diaphoresis (wet skin) whereas anticholinergics produce dry skin and urinary retention
• Formication (the sensation of insects crawling on skin) strongly suggests chronic stimulant use ("cocaine bugs")
• Cocaine-associated chest pain warrants benzodiazepines and nitrates; give aspirin and treat as ACS if ischemia is present

Why Amphetamine use disorder is correct

• The collateral history establishes a problematic 12-month pattern: escalating near-daily use, repeated failed attempts to cut down, and continued use despite job loss — meeting DSM-5-TR criteria for a stimulant use disorder (>=2 of 11 criteria over 12 months), with the substance specified as amphetamine-type by the positive screen.
• The acute picture is a classic sympathomimetic toxidrome consistent with stimulant intoxication: hyperthermia, tachycardia, hypertension, mydriasis, diaphoresis (moist skin), agitation, and paranoia from the mesolimbic dopamine surge of amphetamine.
• Methamphetamine-specific clues reinforce chronic use: dental decay ("meth mouth"), excoriated skin from picking, and the days of anorexia and insomnia.

Why the others are wrong

• Bipolar I disorder, manic — can mimic stimulant intoxication with decreased sleep and agitation, but it is diagnosed only when symptoms persist independent of substance use; the positive amphetamine screen, the autonomic toxidrome, and the documented problematic use pattern point to a substance-related disorder.
• Primary psychotic disorder — implies persistent psychosis with a chronic course independent of intoxication; here psychosis arises acutely alongside a sympathomimetic toxidrome and a positive amphetamine screen, so it is stimulant-related rather than primary.
• Serotonin toxicity syndrome — shares the hyperthermia, tachycardia, hypertension, and agitation, but it requires a serotonergic agent and is defined by inducible clonus, hyperreflexia, and lower-extremity-predominant rigidity, none of which are present, and it would not explain the 12-month pattern of escalating stimulant use.
• Cocaine use disorder — a smoked stimulant can mean crack cocaine, which produces the same sympathomimetic toxidrome and paranoia, but standard urine immunoassays detect cocaine through its metabolite benzoylecgonine rather than as amphetamines, and the marked dental decay is a classic methamphetamine clue.