If a patient feels a slight burning sensation during an injection, what is the most likely cause?

A slight burning sensation during an injection is most commonly attributed to the low pH of the local anesthetic solution. The majority of local anesthetics are weak bases that are typically formulated in a slightly acidic solution to maintain their stability and prolong shelf life. When the solution is injected, the low pH can irritate the tissues, leading to a burning sensation at the injection site.

While a high concentration of epinephrine could potentially cause discomfort, it is more associated with other systemic reactions rather than a direct burning sensation. Infection at the injection site could result in pain or discomfort, but it would not typically produce a burning sensation during the injection unless there is active inflammation present. A rapid injection technique can cause pain or discomfort as well, but the primary cause of a burning sensation specifically relates to the pH of the anesthetic.

Understanding the chemical properties of local anesthetics, including their pH and how it interacts with human tissues, is crucial for improving patient comfort during procedures.