Novocaine Injection Bump: Causes, Timeline & When to Call Your Dentist

Bump After Dental Anesthetic Injection

A small, tender lump at the injection site is common and usually benign.

Causes

• Local trauma: Needle penetration causes minor tissue injury, bleeding, inflammation.
• Solution volume: 1.8 mL cartridge distends tissue.
• Vasoconstrictor (epinephrine): Prolongs anesthesia but causes temporary ischemia → reactive swelling.
• Hematoma: Nicked vessel → blood collection.

Typical Course

• Peaks at 24–48 hours.
• Resolves in 3–7 days.
• No treatment needed beyond observation.

When to Contact Your Dentist

• Swelling worsens after 48h or persists >1 week.
• Increasing pain, redness, warmth, pus (infection).
• Difficulty opening mouth (trismus), swallowing, breathing.
• Numbness lasting >8 hours (possible nerve injury).
• Allergic reaction: hives, facial swelling, wheezing.

Self-Care

• Cold compress (10 min on/off) first 24h.
• Soft diet, gentle hygiene.
• Avoid probing.