Toxicology & Substance Use · Topic 3 of 17

Salicylate Overdose

Toxicology · acid–base poisoning

Salicylate Overdose

Respiratory alkalosis plus anion gap acidosis: alkalinize with bicarbonate, protect the patient's own hyperventilation, and dialyze when the brain, lungs or pH fail.

Key numbers

Alkalinize with sodium bicarbonateUrine pH 7.5–8.5

Dialyze for AMS, ARDS, level > 100> 100 mg/dL → HD

01 · Defined byRespiratory alkalosis plus anion gap acidosis

Salicylates stimulate the medullary respiratory center (primary respiratory alkalosis) and independently cause an anion gap metabolic acidosis; early blood gases show the mixed picture, and pure acidosis appears late as toxicity worsens.

02 · GiveAlkalinize with sodium bicarbonate

Give sodium bicarbonate to every symptomatic patient without waiting for a level: a 1–2 mEq/kg bolus, then an infusion targeting serum pH 7.50–7.55 and urine pH 7.5–8.5, which traps salicylate and speeds its excretion.

03 · Defined byDialyze for AMS, ARDS, level > 100

EXTRIP: dialyze for altered mental status, ARDS needing oxygen, failing standard therapy, salicylate > 100 mg/dL (> 90 mg/dL with impaired kidney function) regardless of symptoms, or pH ≤ 7.20; intermittent hemodialysis is preferred.

Presentation

What you'll see

Early tinnitus, vomiting, hyperventilationAcute toxicity starts with nausea, vomiting, tinnitus and hyperventilation, then fever, agitation, confusion, seizures, noncardiogenic pulmonary edema, rhabdomyolysis and AKI; hyperventilation gives way to hypoventilation and respiratory failure.

Diagnosis & monitoring

Work-up

Acute toxic dose > 150 mg/kgAcute ingestion of more than 150 mg/kg can cause severe toxicity; less than 5 mL of oil of wintergreen (methyl salicylate) can kill a young child, and bismuth subsalicylate is a hidden source.

Do right now

In this order

First moves

Serial salicylate levels with simultaneous blood gases

→

Alkalinize with sodium bicarbonateUrine pH 7.5–8.5

→

Replete potassium or the urine won't alkalinize

→

Dialyze for AMS, ARDS, level > 100> 100 mg/dL → HD

Why each step

Serial salicylate levels with simultaneous blood gasesMeasure a salicylate level with a blood gas, electrolytes, glucose, creatinine and urine pH, and repeat levels every few hours: absorption is erratic (bezoars, enteric coating) and the first level can be low.

Alkalinize with sodium bicarbonateGive sodium bicarbonate to every symptomatic patient without waiting for a level: a 1–2 mEq/kg bolus, then an infusion targeting serum pH 7.50–7.55 and urine pH 7.5–8.5, which traps salicylate and speeds its excretion.

Replete potassium or the urine won't alkalinizeHypokalemia prevents urine alkalinization: give potassium (about 40–60 mEq initially and in the bicarbonate infusion) and monitor serum potassium closely.

Dialyze for AMS, ARDS, level > 100EXTRIP: dialyze for altered mental status, ARDS needing oxygen, failing standard therapy, salicylate > 100 mg/dL (> 90 mg/dL with impaired kidney function) regardless of symptoms, or pH ≤ 7.20; intermittent hemodialysis is preferred.

Management

Orders

Bicarbonate drip: D5W, 150 mEq NaHCO₃, KClA typical alkalinizing infusion is 1 L D5W with three 50-mEq ampules of sodium bicarbonate and 40 mEq KCl at 1.5–2 times maintenance, correcting volume first and watching for pulmonary edema.

Activated charcoal, repeated if absorption continuesGive activated charcoal 1 g/kg (up to 100 g) if the airway is protected; repeat doses are reasonable when levels keep rising from continued absorption.

Give dextrose for altered mental statusBrain glucose can be low even when serum glucose is normal: give IV dextrose to salicylate-poisoned patients with altered mental status, and treat hypoglycemia aggressively.

Severe toxicity: ICU, labs every 2–4 hoursAdmit severe toxicity to the ICU and recheck salicylate level, blood gas, potassium and glucose every 2–4 hours.

Red flags & don'ts

Avoid harm

Avoid intubation; if needed, match hyperventilation avoidAvoid intubation and sedation when possible — apnea and hypercapnia lower the pH and push salicylate into the brain. If intubation is unavoidable, bolus bicarbonate, minimize apnea, match pre-intubation minute ventilation, and dialyze.

No acetazolamide, minimal respiratory depressants avoidAvoid acetazolamide (it worsens systemic acidosis) and, when possible, sedatives or opioids that blunt the compensatory hyperventilation and lower the blood pH.

Acute or chronic salicylate toxicity?

Commonly confused

Typical patient	Intentional ingestion, > 150 mg/kg
Early picture	Nausea, vomiting, tinnitus, hyperventilation
Diagnosis	History plus serial salicylate levels
Dialysis level (Merck)	> 100 mg/dL

More detail

Reference

Show 5 reference facts

Salicylates uncouple oxidative phosphorylation; as weak acids they cross into cells and the CNS more readily when blood pH falls, so acidemia, dehydration and hyperthermia worsen toxicity.

Salicylate can falsely raise measured chloride on some analyzers, producing a misleadingly normal or even negative anion gap.

Treat fever with external cooling and seizures with benzodiazepines; in rhabdomyolysis, maintain hydration and urine output.

Hemoperfusion and continuous kidney replacement therapy are acceptable alternatives when intermittent hemodialysis is unavailable; salicylates are readily removed by extracorporeal treatment.

Early toxicity can raise glucose, but later hypoglycemia is common as gluconeogenesis fails; patients are often several liters volume-depleted from vomiting, hyperthermia and hyperventilation.

Pearl

Never take away a salicylate patient's hyperventilation — a falling pH drives salicylate into the brain.

Sources · Merck Manual Professional — Aspirin and Other Salicylate Poisoning · Juurlink DN et al. Extracorporeal Treatment for Salicylate Poisoning: Systematic Review and Recommendations From the EXTRIP Workgroup. Ann Emerg Med 2015;66:165–181 (abstract via Europe PMC) · Sidlak AM, Spadaro A, Koyfman A, Long B. Acute Salicylate Toxicity: A Narrative Review for Emergency Clinicians. Cureus 2025 · Starter sheet built from the verified AGACNP fact map (facts reviewed 2026-10-15).