What are the side effects and lingering effects of aspirin (acetyl‑salicylic acid) overdose taken a few days ago, including residual dizziness?

Aspirin Overdose Side Effects and Residual Dizziness

Your patient's residual dizziness several days after aspirin overdose likely represents persistent central nervous system toxicity from salicylate accumulation, which is a serious sign requiring immediate evaluation of current salicylate levels and assessment for ongoing toxicity. 1

Understanding the Clinical Significance

Altered mental status—including subtle cognitive abnormalities, confusion, agitation, or dizziness—reflects salicylate accumulation in the central nervous system and represents end-organ toxicity 1. This is not a benign symptom. Even subtle neurological changes can be harbingers of profound toxicity and are associated with poor outcomes, as salicylate crosses into the CNS more readily when acidemia is present.

Key Point About Timing

The fact that symptoms persist "a few days" after overdose is concerning because:

• Salicylate toxicity can have delayed presentations 2
• Rebound toxicity can occur even after initial treatment, with salicylate levels rising again hours after apparent improvement 3
• Chronic or ongoing absorption from enteric-coated formulations can prolong toxicity

Immediate Actions Required

Check current salicylate level immediately - do not assume the overdose has resolved simply because time has passed. The patient needs:

• Current serum salicylate concentration
• Arterial blood gas to assess acid-base status (pH is critical)
• Basic metabolic panel (potassium, bicarbonate, renal function)
• Mental status examination to document degree of impairment

Complete Spectrum of Aspirin Overdose Effects

Central Nervous System Effects

• Tinnitus (ringing in ears) - occurs in 0.8% even at therapeutic doses 4
• Hearing loss/deafness - reported in 0.3% at therapeutic doses, more common at high doses 4
• Dizziness and altered consciousness - occurs in 62% of severe poisonings 1
• Confusion, lethargy, disorientation 5
• Seizures (11% of severe cases) 1
• Coma in severe cases 5
• Cerebral edema (found at autopsy in fatal cases) 1

Respiratory Effects

• Tachypnea and hyperpnea (rapid, deep breathing) 6
• Respiratory alkalosis initially 3
• Acute respiratory distress syndrome (ARDS) - particularly in chronic toxicity 1
• Hypoxemia requiring supplemental oxygen 1

Gastrointestinal Effects

• Nausea and vomiting (22% of severe cases) 1
• Heartburn (2.1% at therapeutic doses) 4
• Hematemesis (vomiting blood) 6
• Gastrointestinal bleeding (1.0% even at therapeutic doses, though usually not serious) 4
• Stomach pain 7

Metabolic Derangements

• Mixed acid-base disturbance - respiratory alkalosis with metabolic acidosis 3
• Severe acidemia (pH <7.2 associated with poor outcomes) 1
• Hypoglycemia or hyperglycemia 5
• Hypokalemia (low potassium) 1
• Electrolyte imbalances 5

Other Systemic Effects

• Hyperthermia (43% of severe cases) 1
• Hypotension (15% of cases) 1
• Pulmonary edema (5% of cases) 1
• Acute kidney injury (15% of cases) 1

Allergic Reactions (from FDA labeling)

• Hives 7
• Facial swelling 7
• Asthma/wheezing 7
• Anaphylactic shock 7

Critical Decision Points for Your Patient

When to Consider Hemodialysis

Based on EXTRIP guidelines 1, extracorporeal treatment (preferably intermittent hemodialysis) is indicated for:

1. Altered mental status (including persistent dizziness/confusion) - 1D recommendation
2. Salicylate level >7.2 mmol/L (100 mg/dL) after acute overdose - 1D recommendation
3. Salicylate level >6.5 mmol/L (90 mg/dL) - 2D recommendation
4. Severe acidemia (pH <7.2) - 2D recommendation
5. Failure of standard therapy (bicarbonate, supportive care) - 1D recommendation
6. New hypoxemia requiring oxygen - 1D recommendation

Standard Supportive Care

If hemodialysis is not indicated, management includes:

• Intravenous bicarbonate infusion to maintain blood pH >7.5 and urine pH >7.5 3
• Aggressive potassium and magnesium repletion 3
• Aggressive hydration to maintain euvolemia 3
• Activated charcoal (if recent ingestion and no contraindications) 6

Common Pitfalls

1. Assuming resolution based on time alone - Enteric-coated aspirin can have delayed absorption up to 24 hours 6, and rebound toxicity can occur 3

2. Ignoring subtle neurological symptoms - Dizziness, mild confusion, or agitation may be dismissed but actually indicate CNS salicylate accumulation and warrant aggressive treatment 1

3. Relying solely on salicylate levels in chronic toxicity - Blood levels are good prognostic indicators for acute ingestions but have limited value in chronic, therapeutically-induced salicylism 5

4. Delaying hemodialysis - The availability of urinary alkalinization may erroneously lead clinicians to delay hemodialysis when it's actually indicated 1

5. Inadequate monitoring duration - Follow-up should continue for approximately 12 hours after non-enteric-coated products and 24 hours after enteric-coated aspirin 6

Bottom Line for Your Patient

This patient needs immediate reassessment with current salicylate levels and acid-base status. Persistent dizziness days after overdose is not a benign symptom—it suggests ongoing CNS toxicity. If current salicylate levels remain elevated or mental status is impaired, consider hemodialysis consultation. At minimum, ensure bicarbonate therapy is optimized and monitor closely for clinical deterioration.