Problems Getting Numb?

 Patients sometimes report that it is difficult for them to achieve adequate “numbness” for routine dental procedures.  Fortunately there are a variety of local anesthetics as well as various techniques for delivering them.  It is a very rare occurrence when we cannot find some combination of anesthetic and technique to help our patients to feel adequately numb.  There are, however, some very interesting reasons why patients may have such problems.  Most of these can be prevented once the causes are understood. 

Anything that causes the pH, or acidity level, of the body to be abnormal can result in poor anesthetic performance.  These agents require a very narrow pH range in order to be effective.  So, if a patient is taking high levels of vitamin C, for example, the body’s pH may be to low.  For these patients, curtailing the vitamin usage for two days before their appointment will be most helpful.  Similarly, when a patient has an acute infection, the pH in the vicinity of the infection may be off requiring additional anesthetic or a different method of delivering it.  It would be much better to have the problem treated before it becomes a full-blown acute infection.  In some cases, these patients will need to begin antibiotic therapy for a couple of days before proceeding with necessary treatment.  The lesson?  If a problem is suspected, have it checked out sooner rather than later to avoid unnecessary discomfort, expense and loss of time. 

Similarly, if a person grinds or clenches, her muscles may have a build up of lactic acid similar to that when we exercise any muscle heavily.  In this case, the pH is thrown off due to the accumulation of the lactic acid.  Such patients will benefit by taking a Tums ™ tablet three times a day for three days prior to their dental appointment.

Others experience anesthetic that does not seem to last long enough.  Sometimes, one’s metabolism can be in high gear contributing to the short-lived effects of the anesthetic.  For example, patients who are very nervous may have this issue.  Similarly, those who have had significant caffeine may have the same problem.  Limiting the coffee or energy products on the day of your dental appointment will be helpful.  For those who are very nervous, a mild oral sedative may be the solution.

A small group of patients may have a rather rare genetic disorder called Ehlers-Danlos  Syndrome which effects various tissues in the body.  These patients may experience joint hypermobility, stretchy skin and may be easily bruised.  These patients also may not become adequately numb for dental procedures.  These patients may need additional anesthetic as well as more frequent doses.

Believe it or not, there is some evidence that people with red hair may have more difficulty achieving adequate numbness.  The same gene  which results in red hair and fair skin is the culprit.  Redheads may just need additional anesthetic to feel adequately numb.

Here are some basic rules to follow to insure the best result from your local dental anesthetic:

  1. Have a restful night’s sleep before your dental visit.
  2. Do not rush around and try to do a day’s work in a couple of hours before your visit.
  3. Avoid caffeine products especially the day of your visit.
  4. If you have had difficulty achieving adequate numbness in the past, try taking Tums™ three time per day for three days before your appointment.
  5. Talk to your dentist about your experiences with anesthetics as well as any concerns you may have.


If you have additional questions or concerns about dental anesthetics, it will be our pleasure to speak with you about them.  You may reach us online at or by telephone at 908.359.6655.