The first mentioning of local anesthetics dates back to 1904. Currently, the medications are used to prevent major pain related to surgical and dental procedures. Besides, they are available in an injectable form to prevent the occurrence and eliminate the already existing symptoms of uneven heartbeats, in eye drops for specific surgical eye procedures, in topical form for numbing the skin and oral. The most frequently used anesthetics include Lidocaine, Procaine, Mepivacaine and Benzocaine.
Possible Side Effects as Reaction to Local Anesthetic
The use of local anesthetics may trigger many symptoms, including both allergic and non-allergic. They may include:
- Heart palpitations or advanced heart rate;
- Symptoms of anaphylaxis;
- Contact dermatitis;
- Itching, swelling, hives and similar signs around the body.
Potential Causes of Negative Reactions to Anesthetics
Despite reactions to local anesthetics are rather common, they are rarely stimulated by allergic causes. The reasons of symptoms appearing after anesthetics use can be various, including vaso-vagal reactions, anxiety, toxic drug effects, hyperventilation, reactions to epinephrine, etc. Besides, a patient can experience an allergic reaction to preservatives, which are added to local anesthetics.
The most common preservative that is added to multi-use vials of anesthetics is called Methylparabens. An allergic reaction to this component is more common that the reaction to local anesthetics. True allergies can also occur, but they are extremely rare. Despite a great range of investigations and studies considering adverse reactions from the use of anesthetics, in fact, they are few. Skin testing proved that almost all people using local anesthetic showed no evidence of allergic reactions to it, and they were able to tolerate the injection quite well.
During the procedure, it is important to take possible latex allergy into consideration, as standard latex gloves are widely used in dental and medical industries. Additionally, certain medications, which are used in spinal anesthesia, can contain Sulfites that may serve another significant risk factor.
Finally, contact dermatitis may also occur during the procedure. A blistering, itchy rash can appear at the site of application or injection of local anesthetic.
How Can Allergy to Anesthetics Be Diagnosed?
Skin testing can be of great help in estimation of adverse reactions to the medications. Allergists have several approaches to diagnosing the condition, still, an overwhelming majority of them will perform skin testing. Most allergists perform tests with epinephrine-free and preservative-free anesthetics to eliminate the risk of other reactions. If the test is negative, subcutaneous injections are used with specific local anesthetics.
Such process is called a ‘challenge”, when a person gets a typical dose of anesthetic he/she may encounter, either at the dentist’s or during a minor surgery. Once a person tolerates the medication well, it means this medication can be used in the future for this patient.
Other allergists will use the most common anesthetic while skin testing. Lidocaine with Methylparabens are generally well-tolerated by the majority of people, so it is a widely used form of local anesthetic.
If the skin test is positive, a person needs to undergo another skin test, using another local anesthetic with Methylparaben-free formula. The most common alternatives for Lidocaine are Etidocaine, Bupivacaine, Prilocaine and Mepivacaine.
Reactions to the anesthetic can appear at the site of the injection hours or even days after testing or challenge. This can serve the sign of contact dermatitis to anesthetics that can be diagnosed with patch testing. Generally, patients with contact dermatitis to certain local anesthetic can tolerate another one.
How Can the Allergy Be Treated?
The treatment of local anesthetic side effects is similar to that of other reactions, caused by other medications. Once you have noticed the symptoms of anaphylaxis, you may require antihistamines or epinephrine, as well as intravenous fluids to decrease shock and advance low blood pressure.
Apart from the treatment, prevention is a significant aspect. Skin testing and other procedures should be performed under directions and supervision of a qualified allergist. Once the doctor has proved a certain local anesthetic to be safe and effective for you, only this specific medicine should be taken in the future. Still, reaction to different local anesthetics may be possible.