What is the appropriate management for a teenager presenting with anxiety, paranoia, vomiting, and tachycardia?

Management of Teenager with Anxiety, Paranoia, Vomiting, and Tachycardia

This presentation demands immediate evaluation for drug toxicity syndromes—particularly serotonin syndrome, anticholinergic toxicity, or sympathomimetic intoxication—before attributing symptoms to primary anxiety disorder, as these life-threatening conditions present identically and require specific antidotal therapy. 1

Immediate Assessment Priority: Rule Out Medical Emergencies

The combination of autonomic hyperactivity (tachycardia), gastrointestinal symptoms (vomiting), and altered mental status (anxiety, paranoia) constitutes a drug toxicity syndrome until proven otherwise. 1

Critical Differential Diagnosis

Drug-induced syndromes to exclude immediately:

• Serotonin syndrome: Recent SSRI initiation/dose increase, combination with other serotonergic drugs; presents with agitated delirium, tachycardia, tachypnea, hypertension, diaphoresis, hyperreflexia/clonus, mydriasis, and hyperactive bowel sounds 1
• Anticholinergic toxicity: Exposure to antihistamines, tricyclics, or anticholinergics; presents with tachycardia, hyperthermia, agitated delirium, mydriasis, hot/dry/erythematous skin, and absent bowel sounds ("red as a beet, dry as a bone, hot as a hare, blind as a bat, mad as a hatter") 1
• Sympathomimetic intoxication: Cocaine, amphetamines, "bath salts," or MDMA use; presents with paranoia, agitation, tachycardia, hypertension, hyperthermia, and mydriasis 1

Essential Physical Examination Findings

Examine specifically for:

• Neuromuscular signs: Hyperreflexia with clonus (serotonin syndrome), lead-pipe rigidity (neuroleptic malignant syndrome), or normal tone (anticholinergic) 1
• Skin: Diaphoretic (serotonin/sympathomimetic) versus hot/dry/flushed (anticholinergic) 1
• Pupils: Mydriasis suggests serotonin syndrome, anticholinergic toxicity, or sympathomimetic use 1
• Mucous membranes: Sialorrhea (serotonin syndrome) versus dry (anticholinergic) 1
• Bowel sounds: Hyperactive (serotonin syndrome) versus hypoactive/absent (anticholinergic) 1

Targeted History

Obtain medication/substance exposure history:

• Recent initiation or dose increase of SSRIs, SNRIs, or other serotonergic agents 1
• Use of antihistamines, diphenhydramine, tricyclic antidepressants, or anticholinergic medications 1
• Recreational drug use including stimulants, hallucinogens, or synthetic cathinones 1
• Over-the-counter cold preparations, sleep aids, or supplements 1

Medical Conditions That Mimic Anxiety

Before diagnosing primary anxiety disorder, exclude:

• Hyperthyroidism/thyroid storm: Check thyroid function tests if tachycardia persists, heat intolerance, or tremor present 1
• Hypoglycemia: Obtain immediate glucose if diabetic or altered mental status 1
• Cardiac arrhythmias: Supraventricular tachycardia can present identically to panic attacks with palpitations, chest discomfort, dizziness, and anxiety; obtain ECG 1, 2
• Pheochromocytoma: Consider if episodic hypertension, headache, and diaphoresis 1

Laboratory testing indicated by clinical suspicion:

• Glucose, electrolytes if vomiting is severe 1
• Thyroid function if tachycardia persists after stabilization 1
• ECG to exclude arrhythmia and QTc prolongation 1
• Urine drug screen has limited utility for acute management but may identify substance use 1

Acute Management Algorithm

If Drug Toxicity Syndrome Identified:

For serotonin syndrome:

• Discontinue all serotonergic agents immediately 1
• Benzodiazepines (lorazepam 1-2 mg IV/IM or midazolam 0.05-0.1 mg/kg) for agitation and muscle hyperactivity 1
• Cyproheptadine (serotonin antagonist): 12 mg initial dose, then 2 mg every 2 hours for continuing symptoms; pediatric dose 0.25 mg/kg/day 1
• Aggressive cooling measures for hyperthermia 1
• In severe cases with rigidity: consider paralysis with nondepolarizing agents (vecuronium/rocuronium) and intubation; avoid succinylcholine due to hyperkalemia risk 1

For anticholinergic toxicity:

• Supportive care with benzodiazepines for agitation 1
• Physostigmine for severe cases with prolonged QRS or dysrhythmias 1
• Sodium bicarbonate for cardiac conduction abnormalities 1

If Primary Anxiety/Panic Disorder After Exclusions:

Acute symptom management:

• Benzodiazepines are first-line for acute severe anxiety with autonomic symptoms: lorazepam 0.5-1 mg PO/IM (adolescent dosing) 1
• Provide reassurance that symptoms, while distressing, are not dangerous 3
• Monitor vital signs until tachycardia resolves 1
• Antiemetics (ondansetron) for persistent vomiting, but note QTc prolongation risk 1

Monitoring Requirements

All patients receiving chemical management require:

• Continuous cardiorespiratory monitoring 1
• Pulse oximetry 1
• Serial vital signs every 15-30 minutes until stable 1
• ECG if antipsychotics or multiple QTc-prolonging medications used 1

Disposition and Follow-Up

Admit if:

• Drug toxicity syndrome requiring antidotal therapy 1
• Suicidal ideation or self-harm risk (24% of anxious adolescents report suicidal ideation) 1
• Severe agitation requiring chemical/physical restraint 1
• Inability to maintain hydration due to vomiting 1

Discharge with outpatient follow-up if:

• Medical causes excluded 1
• Symptoms resolve with supportive care 1
• No safety concerns 1
• Reliable caregiver present 1

Outpatient management plan:

• Cognitive-behavioral therapy is first-line for anxiety disorders 1, 4
• SSRIs (sertraline 25 mg daily starting dose, fluoxetine 10 mg daily, or fluvoxamine 25 mg daily) for moderate-to-severe anxiety 5, 4
• Combination CBT plus SSRI superior to either alone for moderate-severe cases 5, 4
• Screen for comorbid depression (highly comorbid with anxiety, especially generalized anxiety disorder) 1

Critical Pitfalls to Avoid

• Never assume "just anxiety" without excluding drug toxicity syndromes—the presentations are clinically indistinguishable and drug-induced syndromes require specific antidotes 1
• Do not miss cardiac arrhythmias—supraventricular tachycardia causes identical symptoms to panic attacks and may be misdiagnosed as psychiatric; catheter ablation can cure patients misdiagnosed with panic disorder 2
• Avoid antipsychotics in serotonin syndrome—they may worsen rigidity and lower seizure threshold 1
• Do not use indirect sympathomimetics (dopamine) for blood pressure management in drug toxicity syndromes—use direct-acting agents (norepinephrine, phenylephrine) instead 1
• Screen for suicidality—6% of anxious adolescents attempt suicide, with highest risk in generalized anxiety disorder with comorbid depression 1