Bedside Snapshot
- Normal / Therapeutic
- Not detected without recent use. No E3 textbook states a therapeutic serum range: anti-inflammatory dosing is followed by level and symptoms, and toxicity begins above about 30 mg/dL (2.2 mmol/L)
- Toxic Thresholds
- >30 mg/dL (2.2 mmol/L) acute toxicity; >100 mg/dL (7.2 mmol/L) EXTRIP dialysis (>90 with kidney impairment)
- Toxicity Looks Like
- Tinnitus, nausea, vomiting
- Tachypnea; respiratory alkalosis, then metabolic acidosis
- Confusion, seizures, pulmonary edema
- Antidote / Definitive Care
- No antidote. IV sodium bicarbonate to alkalinize urine; hemodialysis per EXTRIP; toxicology consult
- Act Now If
- Level >30 mg/dL or altered mental status: start IV bicarbonate, check glucose, call toxicology; notify the receiving team
- Watch Out For
- A low early level does not rule out toxicity: repeat every 2 h until falling; a normal or acidic pH with fatigue means failing compensation
Reference & Critical Ranges
Lab-specific ranges: The range on your lab report is the one to use. Labs, analyzers and populations all shift it. The values below are typical only.
Reference ranges
| Population | Conventional | SI | Notes |
|---|---|---|---|
| No recent aspirin or salicylate use | Not detected | Not detected | Reporting limit varies by laboratory |
| Adult, anti-inflammatory dosing | Lab- and protocol-specific | No universal SI range | No E3 textbook states a therapeutic serum range. Lewis monitors levels above 3.6 g/day and Katzung follows nonacetylated salicylates at 3–4 g/day by serum level. Katzung gives a toxicity threshold of 30–50 mg/dL; Rosen's puts the zero-order elimination breakpoint above 30 mg/dL and grades toxicity by symptoms, not by a serum level |
| Children | Same as adult | Same as adult | Same toxicity thresholds; judge by clinical state |
Severity & critical values
| Level | Concentration | When to draw | Meaning |
|---|---|---|---|
| Expected on therapy | Below about 30 mg/dL (2.2 mmol/L), no universal range | Any time | Followed by symptoms and level. Chronic toxicity can occur at modest levels |
| Early toxicity | Any level with symptoms; can begin at levels expected on therapy | With symptoms | Tinnitus, nausea, vomiting and hyperventilation can begin; judge by the clinical picture |
| Toxic (acute) | >30 mg/dL (2.2 mmol/L) | Serially, 2 h apart until falling | Start IV bicarbonate; call toxicology |
| Dialysis range | Recommended: >100 mg/dL (7.2 mmol/L), or >90 mg/dL with impaired kidney function. Suggested: >90 mg/dL (6.5 mmol/L), or >80 mg/dL with impaired kidney function, or pH ≤7.20 | Serially | EXTRIP dialysis criteria apply (see Management) |
| Critical | >100 mg/dL (7.2 mmol/L), or altered mental status or ARDS requiring oxygen at any level | Any time | Hemodialysis recommended by EXTRIP |
Critical values (typical; lab-specific): Critical if >100 mg/dL (7.2 mmol/L), or altered mental status or ARDS needing oxygen at any level. In acute ingestion, toxic is >30 mg/dL (2.2 mmol/L). The dialysis line sits at >100 mg/dL, or >90 mg/dL with impaired kidney function.
Conversion: mg/dL × 0.0724 = mmol/L (30 mg/dL = 2.2 mmol/L; 100 mg/dL = 7.2 mmol/L)
Causes of Abnormal Results
Sources & routes of exposure
| Source | Examples | Bedside clue |
|---|---|---|
| Aspirin (acetylsalicylic acid) | Immediate-release, enteric-coated and extended-release tablets; OTC analgesics up to 500 mg per dose | Repeated dosing for pain or fever over days; ask about enteric-coated or extended-release products |
| Oil of wintergreen (methyl salicylate) | Concentrated liniments and topical rubs | Strong wintergreen odor; a small volume can cause toxicity in a child |
| Bismuth subsalicylate | Antidiarrheal and upset-stomach liquids and tablets | Ask about use with aspirin products; bismuth can also darken stool and tongue |
| Herbal products | Willow bark preparations | Often not reported as a medication; ask directly |
Risk factors for toxicity
| Factor | Why it matters | Practical point |
|---|---|---|
| Older age and high respiratory rate | Associated with severe outcome in ED series | Treat early when tachypnea is present in an older adult |
| Impaired kidney function | Lower clearance; lowers the dialysis threshold | Use the lower EXTRIP thresholds (>90 mg/dL) |
| Acidemia | A lower pH increases the un-ionized fraction of salicylate, which crosses into the CNS more easily | Correct acidemia with bicarbonate; do not let pH fall |
| Hypoalbuminemia | Less protein binding, so more free (active) salicylate | Interpret the level with the albumin and the clinical picture |
| Volume depletion | Reduces renal salicylate excretion; fluid deficits of up to 4–6 L are described | Replace volume with isotonic fluid and monitor urine output; avoid overload (pulmonary or cerebral edema) |
| Chronic therapy | Accumulates over days; severe toxicity can occur at lower levels | Assess clinically; do not rely on the number alone |
Acute vs acute-on-chronic vs chronic
| Pattern | Definition | Presentation | Level interpretation |
|---|---|---|---|
| Acute | Single ingestion over a short period (<8 h); doses of about 150 mg/kg or more may cause toxicity | Often a clear history; tinnitus, vomiting, tachypnea | Serial levels to find the peak; the level tracks severity best |
| Acute-on-chronic | Acute ingestion on top of ongoing therapeutic use | Mixed picture; confusion, tachypnea and acidosis | Treat at the level and clinical state; a lower level can be dangerous |
| Chronic | Repeated doses over days, usually older adults | Insidious; often mistaken for sepsis, pneumonia or delirium | No fixed numeric threshold; severe toxicity can occur at lower levels |
Interpretation & Bedside Approach
Step-by-step approach
- Is it real? Confirm the ingestion time, product and amount. A low early level is not the all-clear. Absorption can be delayed, so toxicity is still possible.
- How sick is the patient? Check mental status, respiratory rate, tinnitus, SpO₂ and signs of pulmonary edema.
- Acid–base and glucose: Get a blood gas, electrolytes and glucose. Acidosis is pH <7.3 or bicarbonate <16 mEq/L.
- Trend the level: Repeat every 2 hours until it is clearly falling. Flat or rising? Think ongoing absorption, a late ingestion or a dialysis rebound.
- Classify with EXTRIP: Compare the level, kidney function, mental status, oxygenation and pH with the dialysis criteria.
- Escalate: Consult toxicology early; involve nephrology for dialysis; ICU admission for altered mentation or hypoxia.
Pattern & what it suggests
| Pattern | Suggests |
|---|---|
| Tachypnea with respiratory alkalosis alone | Early toxicity; check a level and repeat |
| Respiratory alkalosis plus metabolic acidosis | Significant toxicity; start alkalinization |
| Metabolic acidosis with altered mental status | Severe toxicity; check lactate and glucose; dialysis discussion |
| Normal or acidic pH with rising PaCO₂ | Respiratory compensation failing; urgent ICU and dialysis review |
A normal or acidotic pH is a danger sign. Respiratory compensation has failed. Now the patient matters more than any single value.
Management Priorities
Emergency: Salicylate toxicity with level >30 mg/dL or altered mental status
- Support the airway and ventilation: Hold minute ventilation high. Skip intubation unless it is truly unavoidable.
- Alkalinize: Sodium bicarbonate bolus, then infusion. Aim for urine pH 7.5 or higher (the AACT/EAPCCT first-line position, Proudfoot 2004) and serum pH 7.50–7.55 (expert practice). No guideline dose exists for salicylate. The 2025 AHA Part 10 serum pH ceiling of 7.55 was set for sodium-channel-blocker poisoning, not this.
- Replace potassium and check glucose: Hold K⁺ in the normal range. Give dextrose for hypoglycemia or altered mental status.
- Dialysis and consult: Run the EXTRIP criteria. Call toxicology and nephrology early.
Medications
| Drug | Adult dose | Pediatric dose (max) | Onset / key notes |
|---|---|---|---|
| Sodium bicarbonate (IV) | 1–2 mEq/kg IV bolus, then 150 mEq in 1 L D5W at 2–3 mL/kg/h | Same mEq/kg bolus and mL/kg/h infusion, weight-based; no fixed max; titrate to urine and serum pH | Expert practice; no guideline dose for salicylate. AACT/EAPCCT position, Proudfoot 2004: urine alkalinization to urine pH 7.5 or higher is first-line for moderately severe poisoning that does not meet dialysis criteria; hypokalemia is the usual complication, so add potassium. Replace potassium first or with the infusion. Pre-intubation: 2 mEq/kg 5–10 min before induction |
| Potassium chloride (IV) High-alert | 40–60 mEq initially, given in divided doses at the institution's maximum rate (typically no more than 10 mEq/h peripheral; up to 20 mEq/h only via central access with continuous ECG monitoring), plus 40–60 mEq added to the bicarbonate infusion. Confirm urine output before giving potassium | Weight-based per protocol with a maximum rate; no pediatric figure in the sources reviewed; titrate to serum K⁺ | Concentrated potassium: never give as a push or bolus; use a pump; recheck K⁺ at the protocol interval during alkalinization (every 1–2 h is common). Low K⁺ prevents urine alkalinization |
| Dextrose 50% (D50W, IV) High-alert | 25 g IV (50 mL of D50W) for adults with hypoglycemia or altered mental status; repeat per glucose and protocol | 0.5–1 g/kg IV as D10W (5–10 mL/kg) or D25W (2–4 mL/kg); titrate to glucose; no fixed max. Do not give undiluted D50W to infants or young children | Check point-of-care glucose first. The 2025 AHA Part 10 pediatric D10W volume (5 mL/kg, Table 3) is for insulin-glucose therapy in cardiac arrest from suspected hyperkalemia, not for altered mentation. Treat hypoglycemia; some references advise empiric dextrose for altered mental status even when serum glucose is normal (CNS glucose may be low); follow local protocol |
| Activated charcoal (oral or NG) | 50 g usual single dose (up to 1 g/kg) | 0.5–1 g/kg (per protocol; maximum per toxicology) | Within about 1–2 h of ingestion; later only for delayed-release products or bezoar, per toxicology. Avoid if vomiting, ileus or airway unprotected. Multi-dose regimens are a toxicology decision |
Intubation carries high risk: Bicarbonate bolus goes in first. After the tube, the vent has to match the pre-intubation minute ventilation (increase rate or tidal volume). If ventilation falls, the acid rises. CNS salicylate climbs with it, and the patient collapses.
Avoid and monitor
- Avoid acetazolamide: It makes acidemia worse and drives CNS salicylate up.
- Avoid sedatives, opioids and paralytics where possible: they blunt the drive to breathe.
- Hyperthermia: An ominous sign. Reach for external cooling. Antipyretics do not treat it.
- Bicarbonate: watch ionized calcium and sodium during the infusion.
- Fluids: avoid overload. Pulmonary and cerebral edema are the risk.
- Acetaminophen: every intentional overdose gets an acetaminophen level.
Definitive care & disposition
- Hemodialysis (EXTRIP recommended): level >100 mg/dL (7.2 mmol/L), or >90 mg/dL with impaired kidney function; or altered mental status, ARDS requiring supplemental oxygen, or failure of standard therapy. Intermittent hemodialysis is the one to reach for.
- Hemodialysis (EXTRIP suggested): level >90 mg/dL, or >80 mg/dL with impaired kidney function, or pH ≤7.20.
- Duration: Keep going until the patient has improved and the level is below 19 mg/dL (where measured). Recheck after dialysis, because levels can rebound.
- Disposition: Admit to ICU for altered mental status, pulmonary edema, hypoxia or worsening acidosis.
Salicylate alkalinization doses are expert practice with no guideline dose. The potassium rate, activated charcoal and empiric dextrose have no source-verified dose on this page. Follow local protocol and medical direction for those.
Field & Transport Considerations
Point-of-care testing
The salicylate level comes from the lab, not the bedside. At the bedside you have a blood gas analyzer for pH, PaCO₂ and bicarbonate, a glucose meter for hypoglycemia, and electrolytes for K⁺. Each device has temperature and hematocrit limits. Check them and follow your local protocol.
Before and during interfacility transport
- Obtain: ingestion time, product and amount; the time of the last dose; the most recent salicylate level and its trend; blood gas, glucose and K⁺.
- Treatments that change values: A running bicarbonate infusion shifts pH and K⁺. Re-check both on the protocol schedule.
- Re-check cadence: If the level is still above the toxic threshold, repeat it every 2 hours in transit, per receiving facility agreement. Glucose and mental status go on every reassessment.
- Delay or redirect: seizures, hypoxia, pulmonary edema or falling pH: notify the receiving facility before departure or en route.
| Setting | Consideration |
|---|---|
| EMS | No level; treat symptoms, check glucose, and transport with the ingestion history |
| Transport | Bicarbonate infusion running on a pump; K⁺ and pH checked; ventilation matched |
| Receiving ED or ICU | Serial levels, dialysis decision and toxicology consult |
Timing & Kinetics
| Parameter | Value | Clinical implication |
|---|---|---|
| Acute exposure | 150 mg/kg over fewer than 8 h | Defines acute ingestion; start treatment on the history while results are pending |
| Early level | Can be undetectable up to 4 h after ingestion | A low early level does not exclude toxicity |
| Serial levels | Every 2 hours | Continue until the level is clearly falling |
| Absorption | Enteric-coated, extended-release and bezoar-forming ingestions can prolong absorption | Expect a late or second peak; keep repeating the level |
| Dialysis end point | Level below 19 mg/dL and clinical improvement | Stop dialysis only when both are met |
| Rebound | Levels can rise after dialysis ends | Recheck the level after dialysis and before transfer |
Ask about enteric-coated tablets: Enteric coating can push the peak later. One normal early level does not clear the patient.
Special Populations
| Population | What changes | Clinical implication |
|---|---|---|
| Children & adolescents | Small volumes of methyl salicylate (oil of wintergreen) are enough to cause toxicity | Ask about liniments and rubs; involve poison control early; use weight-based dosing. Young children are more prone to hypoglycemia |
| Pregnancy | Dialysis criteria apply to the mother | Treat the mother using the standard sequence; involve toxicology and obstetrics early and in parallel; do not delay alkalinization or dialysis for consultation |
| Older adults | Chronic therapy, lower kidney reserve, and higher risk of severe outcome | Lower threshold to treat and to consult; delirium may be salicylate toxicity |
| CKD and dialysis | Lower clearance; lower EXTRIP dialysis thresholds | Use the lower thresholds and discuss early with nephrology |
Interfering Factors & Pitfalls
Collection & handling
| Factor | Effect | Why | Avoid / fix |
|---|---|---|---|
| Single early level | False − | Peak not yet reached; absorption delayed | Repeat every 2 hours until falling |
| Enteric-coated or bezoar | Late rise | Erratic absorption | Serial levels; re-check after a normal result |
Assay & device
| Factor | Effect | Why | Avoid / fix |
|---|---|---|---|
| High salicylate on one analyzer | False ↑ chloride | Analyzer interference above about 60 mg/dL | Do not treat the chloride alone; check the analyzer or re-run on another method |
Physiologic & treatment
| Factor | Effect | Why | Avoid / fix |
|---|---|---|---|
| Low potassium | Alkalinization fails | Kidney excretes H⁺ instead of K⁺ | Replace potassium; re-check urine pH |
| Respiratory compensation loss | Acidemia worsens | Fatigue or intubation with low ventilation | Match minute ventilation; watch pH |
Common misinterpretations
- A normal level in the first hours can still miss toxicity. Repeat it.
- Respiratory alkalosis looks like good news. It is an early sign of toxicity.
- Don't wait for a high number in chronic toxicity. It can be severe at lower levels.
Physiology & Test Basics
What it measures
This is the serum salicylate concentration, mostly active drug plus its metabolites counted as salicylate. It shows how much was absorbed and how far treatment has to go. Other salicylate-containing products read the same, so the history still matters.
Physiology & regulation
- Salicylate uncouples oxidative phosphorylation, so heat and lactate rise.
- It drives the medullary respiratory center. Early on, that means hyperventilation and respiratory alkalosis.
- Later, organic acids pile up. The result is metabolic acidosis with an anion gap.
- Ionized salicylate gets trapped in alkaline urine. That is how it leaves faster.
How it is measured
Use serum or plasma, in the tube your lab requires. You won't usually see a point-of-care salicylate in EMS or transport.
Why it matters
Three decisions hang on the level and the acid–base pattern: whether to alkalinize, how often to check, and when to dialyze. A level read alone misses how sick the patient is.
Clinical Pearls
Tachypnea with a mixed acid–base picture: Think salicylate. Older adults with delirium, tachypnea and fever can pass for sepsis.
Check glucose in every salicylate patient with altered mental status: Hypoglycemia gets treated fast. Some references advise empiric dextrose for altered mental status even when serum glucose is normal, since CNS glucose may run low. Follow local protocol.
Potassium first: Bicarbonate alkalinizes urine only when K⁺ is on board. Hold urine pH above 7.5 and check it regularly.
Repeat the level until it falls: Every two hours, until the curve turns down. Repeat it again after dialysis, since levels can rebound.
Oil of wintergreen (methyl salicylate) is concentrated: Just a few mL can cause serious toxicity in a child. Ask about topical rubs and call poison control early.
References
- Palmer BF, Clegg DJ. Salicylate toxicity. N Engl J Med. 2020;382(26):2544–2555. https://doi.org/10.1056/NEJMra2010852
- Juurlink DN, Gosselin S, Kielstein JT, Ghannoum M, Lavergne V, Nolin TD. Extracorporeal treatment for salicylate poisoning: systematic review and recommendations from the EXTRIP workgroup. Ann Emerg Med. 2015;66(2):165–181. https://doi.org/10.1016/j.annemergmed.2015.03.031
- Sidlak AM, Spadaro A, Koyfman A, Long B. Acute salicylate toxicity: a narrative review for emergency clinicians. Cureus. 2025;17(9):e91505. https://doi.org/10.7759/cureus.91505
- Peketi et al. Salicylate poisoning and rebound toxicity after dialysis (case report). Cureus. 2024. https://doi.org/10.7759/cureus.60241
- 2025 American Heart Association Guidelines for CPR and ECC, Part 10: Adult and Pediatric Special Circumstances of Resuscitation. Cao D, et al. Circulation. 2025;152(16 suppl 2). https://cpr.heart.org/en/resuscitation-science/cpr-and-ecc-guidelines/adult-and-pediatric-special-circumstances-of-resuscitation; https://doi.org/10.1161/CIR.0000000000001380
- Proudfoot AT, et al. Position paper on urine alkalinization. J Toxicol Clin Toxicol. 2004;42(1):1–26. https://doi.org/10.1081/clt-120028740
Medical Disclaimer
- For Educational Purposes Only: This content is intended for educational reference and should not be used for clinical decision-making.
- Not a Substitute for Professional Judgment: Always consult your local protocols, institutional guidelines, and supervising physicians.
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