Which of the following conditions may contraindicate the use of local anesthesia?

Active infections are a significant contraindication for the use of local anesthesia largely due to the potential for complications. First, an infection can alter the tissue environment, leading to changes in pH and increased acidity in the localized area. This altered state may impact the effectiveness of the local anesthetic, as many of these agents function best at a neutral pH.

Additionally, injecting local anesthetic into an area of active infection can lead to further spread of the infection, as the anesthetic solution may facilitate the migration of bacteria. Moreover, the presence of infection can cause an increased inflammatory response, thereby leading to pain and discomfort for the patient during and after the procedure.

Considering these factors, active infections present significant risks, and it is standard practice to address the infection first before proceeding with any local anesthesia. The other conditions listed do not pose the same level of risk and generally would not contraindicate the use of local anesthesia.