The use of epinephrine in dentistry is found primarily as a small component of the local anesthetic solution. The local anesthetic is what a dentist uses in the injection to get their patient numb. Epinephrine is an important part of the local anesthetic for several reasons. The first is to make sure that the anesthetic stays in the area being treated and is not quickly absorbed. This allows a person to stay numb longer and also reduces the possibility of a toxic reaction to the anesthetic itself. Another important function of the epinephrine is to reduce bleeding that accompanies some dental procedures (dental extractions, biopsies, gum surgery, etc.). Epinephrine causes blood vessels to constrict or tighten, allowing the dentist better visibility during dental procedures.
Despite the obvious importance of epinephrine in dental anesthetics, there are some potential risks. Epinephrine is associated with an increase in blood pressure and the development of cardiac arrhythmias. For this reason, dentists and physicians sometimes restrict the use of epinephrine in dental patients with high blood pressure (hypertension) or other cardiovascular diseases. While this restriction is sometimes prudent, it is often unnecessary. The reason is that a typical dental injection contains only a tiny amount of epinephrine (0.018-0.036 mg). A dentist can safely give between one and two anesthetic carpules to most hypertensive patients without expecting any untoward cardiac side effects.
Epinephrine is an important part of most dental local anesthetic agents, and is safe and effective for most patients. There are some patients that dentists should consider restricting the use of epinephrine, and include those with severe, uncontrolled hypertension, refractory cardiac arrhythmias, those who have had a heart attack or stroke within the last six months, have had a coronary artery bypass graft within the last three months, have unstable angina, have uncontrolled congestive heart failure, or have uncontrolled hyperthyroidism.
Some patients believe that they are allergic to epinephrine because they may have had a bad reaction to a dental anesthetic in the past. True allergic reactions to epinephrine are exceedingly rare, because epinephrine is produced naturally in the body by the adrenal medulla. A person is much more likely to be allergic to a different component of the local anesthetic, such as the preservative, although these reactions are also very rare.