Tetracaine Side Effects
Tetracaine can cause both local and systemic side effects, with the most concerning being potential systemic toxicity that can lead to cardiovascular and central nervous system complications. 1
Local Side Effects
Skin/Tissue Reactions:
- Skin irritation and rash
- Local tissue irritation
- Contact dermatitis
- Delayed wound healing
- Cutaneous reactions 1
Ocular Effects (when used ophthalmically):
- Corneal epithelial defects with repeated use
- Corneal erosion
- Stinging/burning sensation
- Temporary vision changes 2
Systemic Side Effects
Central Nervous System Effects
- Seizures/convulsions
- Dizziness
- Paresthesia (abnormal sensations)
- Hypesthesia (reduced sensation)
- Sedation
- Vertigo
- Headache 3
Cardiovascular Effects
- Cardiac arrhythmias (particularly concerning in infants and children)
- Hypotension
- Cardiovascular depression at high systemic levels 4, 5
Allergic/Hypersensitivity Reactions
- Urticaria (hives)
- Angioneurotic edema
- Anaphylaxis (rare but life-threatening)
- Anaphylactoid purpura 3
Hematologic Effects
- Agranulocytosis
- Hemolytic anemia
- Thrombocytopenia
- Leukopenia
- Neutropenia
- Pancytopenia
- Eosinophilia 3
Special Considerations
Pediatric Patients
- Increased risk of systemic toxicity in premature infants and neonates
- Case reports of arrhythmias in extremely low birth weight infants 4
- Should not be used in large quantities on raw or blistered areas in children 1
Topical Application Warnings
- For external use only
- Avoid contact with eyes
- Do not use in large quantities, particularly over raw surfaces and blistered areas
- Stop use if skin becomes irritated or condition worsens 1
Pharyngeal Use
- Serious systemic toxicity has been reported when used for pharyngeal anesthesia in upper endoscopic procedures 6
Risk Factors for Toxicity
Application site:
- Highly vascular areas increase absorption risk
- Damaged skin/mucous membranes increase absorption
- Large surface area applications
Patient factors:
- Extremes of age (very young or elderly)
- Low body weight
- Hepatic or renal impairment
- Pre-existing cardiac conditions
Medication factors:
- High concentration formulations
- Prolonged application time
- Repeated applications
- Concomitant use of other local anesthetics
Monitoring and Management
- Monitor for signs of systemic toxicity when using tetracaine, especially in high-risk patients
- Early signs of toxicity include perioral numbness, metallic taste, lightheadedness, and tinnitus
- If systemic toxicity is suspected, immediately discontinue the drug and provide supportive care
- For severe reactions, airway management, cardiovascular support, and seizure control may be necessary
Comparative Toxicity
Tetracaine has been shown to be more toxic than other local anesthetics like proparacaine and cocaine in corneal epithelial cell studies, with approximately four times greater toxicity than proparacaine 2. When compared to other local anesthetics in CNS toxicity studies, tetracaine required lower doses to produce convulsive activity compared to lidocaine 5.
When used appropriately at recommended doses and with proper technique, serious adverse effects of tetracaine are rare. However, awareness of potential side effects and appropriate patient selection are essential for safe use.