Adrenaline in dental anaesthesia: when to be careful
- Drugs
Adrenaline makes dental anaesthesia last longer and bleed less. Small amounts, injected carefully, suit most heart patients; a few situations need caution.
What it is
Adding a vasoconstrictor to a local anaesthetic narrows local vessels, which prolongs and deepens anaesthesia, reduces bleeding and slows absorption into the blood (lowering systemic toxicity). The amount of adrenaline in dental cartridges is small, and in most people with controlled cardiovascular disease it is well tolerated if the injection is slow and aspiration confirms the needle is not in a vessel; poor anaesthesia and pain release more endogenous adrenaline than the cartridge. Caution is needed with recent myocardial infarction or stroke, unstable angina, uncontrolled hypertension or arrhythmias, uncontrolled hyperthyroidism, phaeochromocytoma and recent cocaine or amphetamine use.
What to know
- Benefits: longer, deeper anaesthesia; less bleeding; less systemic toxicity.
- Aspirate and inject slowly; limit the number of cartridges in cardiac patients.
- Non-selective beta-blockers: adrenaline can cause a rise in blood pressure with reflex bradycardia.
- Tricyclic antidepressants can enhance the pressor effect.
- Recent cocaine use: avoid adrenaline-containing anaesthetics because of arrhythmia and hypertension risk.
Risks and precautions
- Palpitations and anxiety right after an injection are usually a short adrenaline effect; reassure and monitor.
- Elective dental treatment is usually postponed for some weeks after a myocardial infarction or stroke; emergencies are managed with the medical team.
- Mepivacaine or prilocaine with felypressin are alternatives when adrenaline should be minimised.
Next step / Initial management
- Take a cardiovascular history and blood pressure before treatment in at-risk patients.
- Uncontrolled hypertension or unstable cardiac disease: defer elective care and refer to the treating physician; for dental emergencies, coordinate with the medical team.
- Ask about recreational stimulant use in younger patients with unexplained tachycardia.
Test yourself
Think of the answer, then tap the question to see it.
What are the three benefits of adding adrenaline to a dental local anaesthetic?
Longer and deeper anaesthesia, less bleeding and less systemic absorption (lower toxicity).
What interaction can occur between adrenaline and non-selective beta-blockers?
Unopposed alpha stimulation raises blood pressure, with reflex bradycardia.
Why is adrenaline avoided after recent cocaine use?
Because of the risk of severe hypertension and arrhythmias.
Connections
Educational content; it does not replace assessment by a dentist or doctor and is not a clinical instruction. For facial or neck swelling with difficulty swallowing or breathing, a knocked-out tooth or bleeding that will not stop, go to an emergency department at once.
Sources: Local Anesthetic Drugs Used In Dentistry (StatPearls Publishing (NCBI Bookshelf), 2025); Topical, Local, and Regional Anesthesia and Anesthetics (StatPearls Publishing (NCBI Bookshelf), 2025).
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Representative model, for educational purposes only.