Vasoconstrictors: indications and precautions.

Vasoconstrictors are useful additives to local anesthetic solutions. They can enhance the duration and quality of the anesthetic block while also decreasing surgical blood loss. Precautions must be taken, however, when using vasoconstrictors with certain patients, especially those with cardiovascular disease. Several drug interactions must also be considered before administration of a local anesthetic with a vasoconstrictor, and special care must be taken when injecting such preparations in patients on nonspecific beta-adrenergic blockers, tricyclic antidepressants, catechol-O-methyltransferase inhibitors, cocaine, and certain general anesthetics. Lastly, in the patient with true sulfite allergy, local anesthetics without a vasoconstrictor should be used.