Novocaine Allergy Symptoms

What a Negative Reaction to Local Anesthesia Looks Like

If you are planning to have oral surgery or another surgery requiring a local anesthetic, you might be concerned about the possibility of a novocaine allergy. The good news is that severe reactions to novocaine and other local anesthetics (including the more commonly used lidocaine) are uncommon. When symptoms do occur, they can range from minor swelling to a life-threatening, whole-body reaction.

Female nurse filling syringe
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Many symptoms and side effects, due to allergic and non-allergic causes, can occur as a result of local anesthetic use. These may include:

  • Anxiety
  • Flushing
  • Hyperventilation
  • Trembling or shaking
  • Fast heart rate or palpitations
  • Swelling, itching, or hives, both at the site of injection and elsewhere on the body
  • Contact dermatitis at the site of injection or application

A true allergic reaction to a novocaine injection or another local anesthetic may cause symptoms like swelling at the site of the injection or symptoms of anaphylaxis, a life-threatening allergic reaction. An anaphylactic reaction to novocaine or another local anesthetic may produce symptoms like difficulty breathing and a drop in blood pressure.

Causes of Reactions to Local Anesthetics

Reactions to novocaine and other local anesthetics are relatively common, although they are only rarely due to an allergy. Symptoms occurring after the use of local anesthetics may be due to a variety of other causes, including anxiety, hyperventilation, toxic effects of the drug itself, vasovagal reactions, as well as reactions to epinephrine, which is frequently added to local anesthetics to make the numbing effect last longer.

It is also possible for a person to experience an allergic reaction to preservatives added to local anesthetics. Methylparabens are the most common preservatives added to multi-use vials of local anesthetics.

Allergy to methylparaben, while still uncommon, is far more common than true allergy to local anesthetics themselves.

True allergies to novocaine and other local anesthetics are rare. Numerous large studies of people who experienced adverse reactions after using these medications revealed that nearly all of these people showed no evidence of allergy to local anesthetics and were able to tolerate injections with these medications.

The possibility of latex allergy should always be considered when a person has a reaction to local anesthetics, given the common use of latex gloves in the medical and dental industries. Some medications used in local anesthesia contain sulfites, antioxidants that can cause allergic reactions.

An itchy, red, and/or flaky rash and sometimes even blisters may occur at the site of injection or application of the local anesthetic.

How an Allergy to Local Anesthetics Is Diagnosed

Skin testing can be helpful in the evaluation of an adverse reaction to these medications. Allergists have different ways of approaching a person with a history of an adverse reaction to local anesthetics.

Allergists may choose to test with preservative-free (methylparaben-free), epinephrine-free local anesthetics to see if the reaction is related to an ingredient other than the local anesthetic. Most will, however, perform skin testing with the ultimate goal of giving a person at least one local anesthetic that can be used in the future. If initial skin testing is negative, then the allergist next will try giving subcutaneous (under the skin) injections of that specific local anesthetic.

This is termed a “challenge”, which is essentially giving a person a typical amount of the drug that they might encounter at the dentist or when getting minor surgery. If a person tolerates a medically-supervised challenge using a particular local anesthetic, it is assumed that the person can use this particular drug in the future.

Other allergists may skin test using the most common local anesthetic available—lidocaine with methylparaben. The majority of people will tolerate a challenge using this form of local anesthetic, so this option is the easiest way for a person to overcome the label of being “allergic to all local anesthetics."

In the unusual circumstance that a skin test is positive for a local anesthetic, a repeat skin test using a methylparaben-free formulation or another local anesthetic can be performed.

Some people will notice a reaction at the site of injection hours to days after testing or challenge with a local anesthetic. This may signal the presence of contact dermatitis to local anesthetics, which is best diagnosed with the use of patch testing.

How an Allergy to a Local Anesthetics Is Treated

The treatment of an acute reaction to a local anesthetic is similar to that of a reaction from any other cause. If anaphylaxis occurs, treatment may include injectable epinephrine and antihistamines, as well as the use of intravenous fluids for low blood pressure and shock.

The prevention of future reactions is another important aspect of treatment.

Alternatives to Novocaine

Novocaine is not used as often as it once was. This is because the effects of novocaine only last for between 30 and 90 minutes. Xylocaine (lidocaine) is longer lasting and is preferred for most procedures. Other common alternative local anesthetics include bupivacaine, mepivacaine, prilocaine, and etidocaine.

If you are allergic to novocaine or another local anesthetic, your healthcare provider may want to test you to see if you are also allergic to the alternatives. Skin testing for local anesthetics should be done under the direction of an allergist.

Once a reasonable alternative local anesthetic has been found, your dentist or surgeon will use this instead of the one you are allergic to. It is still possible that you could experience a reaction to a different local anesthetic, however.

If there are no good alternatives, laughing gas (nitrous oxide) may be sufficient for simple procedures. More complicated procedures may need to be performed under general anesthesia.

5 Sources
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By Daniel More, MD
Daniel More, MD, is a board-certified allergist and clinical immunologist. He is an assistant clinical professor at the University of California, San Francisco School of Medicine and currently practices at Central Coast Allergy and Asthma in Salinas, California.