Drilling teeth can be painful. And that makes it hard for children to keep their mouths open. When local anaesthesia is given, the pain coming from the nerve of the tooth is blocked. No longer fearful, children can then relax and let the dentist do their job.

Diego Peroni, a paediatric specialist at the University Clinic in Pisa, Italy, and his team investigated the incidence of side effects from local anaesthetics (LA).

What did the research team do?

The team analysed data from previously published studies. The researchers evaluated the frequency and number of the side effects and how many of these were allergic reactions. They also provided recommendations on how to determine whether a patient is really allergic to LA.

Hypersensitivity is not always an allergy

Side effects to local anaesthetics are rare. No more than one out of 100 children who receive LA will have a reaction. The symptoms range from localised redness and swelling to difficulty breathing, inflammation of the mucosa of the eyes and nose, and severe cardiovascular problems (anaphylaxis).

Only one percent of these reactions are caused by an allergic reaction to the local anaesthetic. All other cases are non-allergic hypersensitivity reactions to the drug.

The difference is that only in the case of the allergy does the immune system develop antibodies in order to mount a defence against the allergen, which it perceives as an unwanted intruder.

If it is not clear what is causing the side effects, it should generally be assumed that the reaction is due to hypersensitivity.

Excluding other causes

In order to find out whether the symptoms are actually associated with the local anaesthetic, all the facts must be considered. For example:

• Does the patient have any known allergies?
• Is the patient taking any medications?
• Is there a correlation in time between the administration of the LA and the onset of symptoms?
• Could other materials, such as latex gloves or dental fillings, be the cause?

Confirming the suspected allergy

If an allergy is still suspected, further examination by an allergy specialist will be required.

The first step should be to perform skin tests, patch tests, intradermal tests and/or prick tests. If there are no conclusive results, a provocation test should be performed next. For this test, the local anaesthetic is given in increasing doses. A provocation test should always be carried out in a hospital setting so that help can be sought quickly in the event of a serious reaction.

Peroni and his team recommend performing the tests within four to six weeks after the symptoms subside. “If you wait six to twelve months, some test results may already come out negative again.”

Original study

Peroni D et al. Allergic manifestations to local anaesthetic agents for dental anaesthesia in children: a review and proposal of a new algorithm.

author: ch/ktg