Is novacaine harmful in early pregnancy?

I just found out that I am four weeks pregnant. Is Novacaine harmful to my unborn baby?


Novacaine used to be a common local anesthetic used in dentistry. Currently, Lidocaine (also called Xylocaine) is used because some patients had allergic reactions to Novocaine. Lidocaine, which is also a local anesthetic, works in essentially the same way as Novocaine, without causing allergic reactions and other side effects. The chemical structure of Lidocaine is different from Novocaine, however. My answers below address local anesthetics in general unless specifically stated otherwise.

On page 2231 of the American Hospital Formulary Service (AHFS) Drug Information (reference), 1995 edition, it states: "Safe use of local anesthetics during pregnancy prior to labor has not been established with respect to adverse effects on fetal development. Careful consideration should be given to this fact before administering these drugs in pregnant women." Injected local anesthetics can cross the placenta. However, the small amounts of Lidocaine used in dentistry probably will not adversely affect a developing fetus. That being said, we usually advise waiting until the second trimester of pregnancy to have dental work done if possible.

If the dental procedure is elective or does not require immediate treatment, you may be able to wait until after your child is born.

Additional details:

Lidocaine works by preventing the initiation and transmission of nerve impulses to the brain. Technically speaking: One current theory is that local anesthetics, in general, reduce nerve cell membrane permeability by competing with calcium for the membrane binding sites that control membrane permeability to sodium. Nontechnically speaking: Without this anesthetic, these impulses would reach the brain and may be interpreted by the brain as pain.

Generally, Novocaine or Lidocaine takes effect in about two to five minutes and is effective for one to two hours depending on the dosage, method of administration, individual patient and other variables. Novocaine and Lidocaine are readily absorbed into the body after administration.

Most studies on the effects of Novocaine on fetal development that I was able to locate, including one entitled "Effect of infusions of glusose-Novocaine mixture on the functional state of delayed-development fetuses", are published in Russian and are very dated. They were not much help.

Other pregnancy-related information:

When women become pregnant, they expect their family physician to answer many questions about potential risks during pregnancy and possible effects on the developing fetus. Many of these questions concern over-the-counter medications, cosmetics, haircare products, insecticides and other common household products. A good article that discusses specific risks and may prevent unnecessary anxiety and needless changes in work and home environment for pregnant women is Hueston, W.J. et al., "Common questions patients ask during pregnancy" American Family Physician (May 1995) 51(6):1465-1470.

My appreciation to George Van Baelen, M.Sc.Ph., Product Information Specialist for Sanofi Winthrop Pharmaceuticals, New York, for the journal reprints and information regarding this topic.

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