Answer
Adrenaline narrows blood vessels near the injection site, reducing lidocaine absorption and extending its local numbing effect.
Sources for this answer
- Lidocaine 2% with adrenaline (epinephrine) 1:200,000 solution for injection — Current selected SmPCemc · Summary of Product Characteristics
General medicine information. Follow the instructions for your own medicine and speak to a pharmacist or clinician about your individual circumstances.