Local Anesthetic Drug Allergy, while drugs are being developed for the treatment of diseases, allergic reactions occur in our body against these drugs. Drug allergies are not actually very common allergic diseases. It has become more common with new drugs every day. Since drug allergies can lead to allergic shock, which can result in death, the diagnosis must be made.
Drug allergies are caused by our immune system’s perception of the drugs we take for treatment as foreign substances and then overreaction to these substances. Although the same drug has been used many times before, it can cause many serious reactions from urticaria (hives) to anaphylactic shock (allergic shock) when used last time.
Since the end of the 19th century, local anesthesia (LA) drugs have been widely used in the world due to their analgesic effects. It is used very frequently, especially by dentists, and is used during many minor surgical procedures. Dentists alone use approximately 200 million local anesthetic drug cartridges annually in the United States. In addition, creams and pomades containing local anesthetics are also used very often.
True allergic reactions to local anesthetics are very rare and account for less than 1% of all reactions. Systemic side effects may develop after the injection of local anesthetic drug solutions. These reactions can range from transient vasovagal attacks of fainting to life-threatening anaphylaxis. Most of the reactions that occur in local drug allergies are caused by the preservatives of local anesthetics.
Although all systemic side effects with local anesthetic drugs are considered to be allergic, non-allergic reactions may also occur with local anesthetic drugs. These may occur due to excessive toxic doses of the drug, rapid circulation, intravenous administration, effects on the cardiovascular and central nervous system, or psychological reasons such as extreme fear.
Diagnosis of Local Anesthetic Drug Allergy
True allergic reactions to local anesthetics are very rare and account for less than 1% of all reactions. Systemic side effects may develop after the injection of local anesthetic drug solutions. These reactions can range from transient vasovagal attacks of fainting to life-threatening anaphylaxis. It is extremely important to take an accurate and detailed anamnesis from patients in local anesthetic drug allergies. If allergic reaction is suspected in patients with a history of reaction to local anesthetic drugs, allergy tests should be performed. Allergy can be detected by skin tests (skin prick tests, intradermal tests) since the mechanism of allergic reactions such as anaphylactic shock with local anesthetic drug is IgE-mediated (Type 1 hypersensitivity).
It is extremely important to take an accurate and detailed anamnesis from patients in local anesthetic drug allergies.
In studies, only 15-37% of patients who applied for allergy testing with a local anesthetic drug had a history of a reaction suggesting a true allergic event to the local anesthetic drug. A detailed medical history may prevent unnecessary testing, but patients may not provide sufficient information. Complaints that occur during the procedure, information about the start and duration of the reaction, whether it contains the drug’s content, dose, preservatives or adrenaline, are very helpful if they are recorded in the clinic where the procedure is performed. The interpretation of the findings and the necessary tests must be done by allergy specialists.
Reaction with local anesthetic drugs
If allergic reaction is suspected in patients with a history of reaction to local anesthetic drugs, allergy tests should be performed.
A patient experiencing a suspicious reaction should be investigated by an allergist. Allergy can be detected by skin tests (skin prick tests, intradermal tests) since the mechanism of allergic reactions such as anaphylactic shock with local anesthetic drug is IgE-mediated (Type 1 hypersensitivity).
The purpose of skin testing should be to find a single local anesthetic drug that the patient can use in future medical interventions and procedures. If a strong anaphylactic reaction is suspected, local anesthetic drugs from different groups can be used. Choosing a local anesthetic from the amide group should always be a priority because its use is very common and allergic reactions are less likely to develop. The recommended agents for comprehensive testing of anaphylactic shock reactions are tetracaine, mepivacaine, lidocaine, and bupivacaine. However, the most commonly prescribed local anesthetics nationally are available for testing.
It is appropriate to perform the patch test for patients with complaints such as contact dermatitis or eczema due to local anesthetic drugs.
Ideally, patients with suspected contact allergy to local anesthetic drugs should be tested with amide and ester local anesthetics and their preservatives, parabens and metabisulfite. Benzocaine, a common ingredient in topical preparations such as sunscreens, sunburnt lotions, and hemorrhoids ointments, is one of the most common causes of allergic contact dermatitis. It is estimated that 5% of individuals exposed to benzocaine will become sensitized. Therefore, if contact dermatitis develops in patients using benzocaine-containing preparations, patch testing is required. The most common cause of contact allergy with lidocaine is ointments or ointments used for pruritus ani (anal itching), anal fissures and fissures.
The local anesthetic drug provocation test used to diagnose local anesthetic drug allergies is considered the gold standard and must be performed.
The local anesthetic drug provocation test is very important because it fully evaluates possible allergic reactions and other adverse effects regardless of the mechanism. If it is necessary to do it after negative skin tests, it must be evaluated and decided by an allergist. The test should not be performed in patients with conditions such as severe asthma or underlying heart disease, and in patients who experience life-threatening immunocytotoxic reactions. ACEIs (Angiotensin converting enzyme inhibitors) used for hypertension should be avoided before testing.
There are also blood tests in the diagnosis of local anesthetic drug allergy.
Leukocyte release test, RAST and basophil activation test can be used in the diagnosis of Type I (early type hypersensitivity) allergic reactions from blood. Lymphocyte transformation test can also be helpful in diagnosing Type IV allergic reactions from blood. Unfortunately, these blood tests are not currently sufficient to diagnose local anesthetic drug allergy. Not all of these tests alone rule out local anesthetic drug allergy.