Burning on injection can be caused by?

Burning on injection can be caused by?

• A. Due to injecting too fast or a lower pH from a vasoconstrictor
• B. Cold anesthetic
• C. Solution contaminated with bacteria
• D. Too slow injection

Answer: (A)

Burning on injection is most likely from the combination of an acidic anesthetic solution and rapid administration. Local anesthetics with vasoconstrictors are kept acidic to preserve the drug and the vasoconstrictor, so when this acidic solution enters tissue the excess hydrogen ions irritate nerve endings, producing a burning or stinging sensation. If the injection is delivered quickly, the rapid tissue distension plus chemical irritation amplifies this burning. Other scenarios don’t fit as well: a cold anesthetic can cause a chilly sensation, but not the characteristic burning; solution contaminated with bacteria would lead to infection signs later rather than immediate burning; and injecting too slowly would not typically cause burning and may even reduce the sharp discomfort.

Burning on injection is most likely from the combination of an acidic anesthetic solution and rapid administration. Local anesthetics with vasoconstrictors are kept acidic to preserve the drug and the vasoconstrictor, so when this acidic solution enters tissue the excess hydrogen ions irritate nerve endings, producing a burning or stinging sensation. If the injection is delivered quickly, the rapid tissue distension plus chemical irritation amplifies this burning.

Other scenarios don’t fit as well: a cold anesthetic can cause a chilly sensation, but not the characteristic burning; solution contaminated with bacteria would lead to infection signs later rather than immediate burning; and injecting too slowly would not typically cause burning and may even reduce the sharp discomfort.