Salicylate poisoning is a life-threatening medical emergency caused by ingestion of acetylsalicylic acid (aspirin) or other salicylate-containing products such as topical liniments, methyl salicylate oils, herbal preparations, and combination medications.

Toxicity results from uncoupling of oxidative phosphorylation, leading to:

• Increased metabolic rate

• Excess heat production

• Metabolic acidosis

• Respiratory alkalosis

• Severe electrolyte disturbances

Severe poisoning may rapidly progress to cerebral edema, pulmonary edema, shock and death if not treated aggressively.

Poisoning may be:

• Acute – large single ingestion (often suicidal)

• Chronic – repeated supratherapeutic dosing (common in elderly)

• Acute-on-chronic – most dangerous

2. Toxic Dose

Methyl salicylate (oil of wintergreen) is extremely toxic: 5 mL ≈ 7 g aspirin equivalent

3. Risk Factors

Patient-related

• Children

• Elderly (chronic toxicity common)

• Renal disease

• Dehydration

• Fever

• Malnutrition

• Pregnancy

Drug-related

• Enteric-coated tablets (delayed toxicity)

• Combination medications

• Topical salicylates

• Herbal medications

4. Pathophysiology

Salicylates produce a mixed acid-base disorder:

1. Direct stimulation of respiratory center → respiratory alkalosis

2. Cellular hypoxia → lactic acidosis

3. Ketoacidosis → anion gap metabolic acidosis

4. Uncoupling ATP → heat production and hyperthermia

Electrolyte abnormalities:

• Hypokalemia

• Hyponatremia

• Hypoglycemia (brain glucose depletion even if serum normal)

5. Clinical Features

Early Signs (0–6 hours)

• Tinnitus (classic hallmark)

• Hearing impairment

• Nausea and vomiting

• Tachypnea (deep rapid breathing)

• Sweating

• Fever

• Restlessness

• Dizziness

• Dehydration

Intermediate Signs (6–24 hours)

• Metabolic acidosis

• Hyperventilation

• Confusion

• Agitation

• Blurred or double vision

• Hypokalemia

Late / Severe Signs

• Drowsiness

• Delirium

• Seizures

• Coma

• Pulmonary edema (non-cardiogenic)

• Cerebral edema

• Shock

• Death

6. Diagnostic Criteria

Diagnosis is based on history + clinical findings + serum salicylate level

Classic diagnostic clues

• Tinnitus

• Hyperventilation

• Mixed metabolic acidosis + respiratory alkalosis

• Fever without infection

• Unexplained altered mental status

7. Investigations

Essential

• Serum salicylate level (every 2–4 hours)

• Arterial blood gases

• Serum electrolytes

• Blood glucose

• Urea & creatinine

• Urine pH

Additional

• Serum ketones

• Lactate

• Chest X-ray (pulmonary edema)

• ECG (electrolyte disturbances)

Interpretation of Salicylate Levels

Important: Clinical condition is more important than level (especially chronic poisoning).

8. Management

General Principles

DO NOT intubate unless absolutely necessary(ventilation reduces respiratory compensation → sudden death)

9. Treatment

A. Emergency Stabilization (ABCDE)

• Airway: Maintain but avoid sedation if possible

• Breathing: Give oxygen

• Circulation: IV access and fluids

• Disability: Check glucose (give dextrose if low or altered consciousness)

• Exposure: Remove contaminated clothing if topical exposure

B. Non-Pharmacological Treatment

1. Gastrointestinal Decontamination

• Activated charcoal (within 1 hour; may repeat every 4 hours)

• Gastric lavage if massive ingestion within 1 hour

• Whole bowel irrigation for enteric-coated tablets

2. Fluid Resuscitation

Use isotonic saline:

• Correct dehydration

• Maintain urine output ≥1–2 mL/kg/hr

3. Urinary Alkalinization (Most Important Therapy)

Target urine pH >7.5

C. Pharmacological Treatment

Sodium Bicarbonate Therapy

D: Sodium bicarbonate (IV) 1–2 mEq/kg slow bolus.

Then infusion: 150 mEq sodium bicarbonate (3 ampoules of 50 ml 8.4%) in 1 litre of 5% dextrose at 150–250 ml/hour, adjusted to keep urine pH 7.5–8.0 and serum pH 7.45–7.55.

• Fluids: A: sodium chloride 0.9% 20 ml/kg IV over 15–30 minutes if hypotensive or dehydrated, then maintenance to keep urine output 1–2 ml/kg/hour.

• Hypoglycaemia: adults C: dextrose 50% 50 ml (25 g) IV then dextrose 5% infusion; children B: dextrose 10% 2–5 ml/kg IV then dextrose-containing fluids.

• Hypokalaemia: C: potassium chloride 20–40 mEq per litre of IV fluid, or 10–20 mEq/hour with ECG monitoring.

• Seizures: A: diazepam 0.15–0.2 mg/kg IV (maximum 10 mg), may repeat once after 5–10 minutes, OR C: lorazepam 0.1 mg/kg IV (maximum 4 mg).

• Avoid acidifying agents; refer moderate–severe poisoning to intensive care early.

Goals:

• Serum pH 7.45–7.55

• Urine pH >7.5

Correct potassium before alkalinization

Glucose

Give dextrose even if serum glucose normal when CNS symptoms present

Electrolyte Correction

• Potassium replacement mandatory

• Correct hypokalemia aggressively

D. Hemodialysis (Definitive Treatment)

Indications

• Salicylate concentration above 700 mg/litre (70 mg/dl)

• Severe metabolic acidosis

• Renal failure, pulmonary oedema or altered mental status

• Failure of bicarbonate therapy

Hemodialysis rapidly:

• Removes salicylate

• Corrects acidosis

• Improves survival

10. Complications

• Cerebral edema

• Pulmonary edema

• Acute kidney injury

• Hypoglycemia brain injury

• Arrhythmias

• Death

11. Special Populations

Children

• Rapid deterioration

• Early acidosis

• Lower toxic threshold

Elderly

• Often chronic toxicity

• Confusion mistaken for stroke or dementia

Pregnancy

• Fetal acidosis occurs earlier

• Dialysis threshold lower

12. Monitoring

Repeat every 2–4 hours:

• Salicylate level

• ABG

• Electrolytes

• Glucose

• Urine pH

Continue until levels declining AND symptoms resolved.

13. Prevention

Do’s

• Store medicines in child-proof containers

• Keep original packaging

• Educate caregivers

• Use correct dosing devices

Don’ts

• Do not transfer tablets into other containers

• Do not leave medicines open

• Do not call medicine candy

• Do not self-medicate chronic pain repeatedly

14. Prognosis

Good with early treatment.Poor prognosis if:

• Altered consciousness

• Pulmonary edema

• Severe acidosis

• Delayed presentation