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Revista Brasileira de Anestesiologia

Print version ISSN 0034-7094On-line version ISSN 1806-907X

Rev. Bras. Anestesiol. vol.54 no.5 Campinas Sept./Oct. 2004 



Allergy to lidocaine. Case report*


Alergia a la lidocaína. Relato de caso



Liana Maria Tôrres de Araújo, M.D.I; José Luiz Gomes do Amaral, TSA, M.D.II

IAnestesiologista do Hospital São Paulo
IICoordenador do Departamento de Anestesiologia da EPM, Hospital São Paulo (HSP)





BACKGROUND AND OBJECTIVES: Although seeming extremely rare, the real incidence of allergy to lidocaine is unknown. Adverse events, such as toxicity or phobic reactions are often interpreted as allergic reactions. Allergic responses in general are caused by preservatives or antioxidants present in anesthetic agents. This report aimed at presenting a case of allergy to spinal lidocaine, to alert health professionals for this possibility with prompt diagnosis and early treatment.
CASE REPORT: Female patient, 16 years old, submitted to laser ureterolythotripsy for ureteral stone resection under sedation and spinal block with 5% lidocaine (50 mg). Minutes later, patient presented erythematous pruriginous plaques on neck and trunk and mild eyelid and lip edema. Patient was treated with prometazine with total reversion of symptoms. Patient was later sent to the Immune-Pediatrics sector where allergic triggering tests were performed. Patient presented positive intradermal test confirming the hypothesis of allergy to lidocaine.
CONCLUSIONS: Allergy to lidocaine is rare, however it is necessary that health professionals are always alert for this fact.

Key Words: ANESTHETICS, Local: lidocaine; COMPLICATIONS: allergy


JUSTIFICATIVA Y OBJETIVOS: Aun cuando parezca ser extremamente rara, la real incidencia de alergia a la lidocaína es desconocida. Eventos adversos como toxicidad o reacciones fóbicas son frecuentemente interpretados como reacciones alérgicas. Las respuestas alérgicas generalmente suceden debido a conservantes o antioxidantes presentes en los agentes anestésicos. El objetivo de este relato es presentar un caso de reacción alérgica a la lidocaína inyectada por vía subaracnóidea, con la finalidad de alertar profesionales de la área de salud para esta posibilidad con diagnóstico rápido e inicio precoz del tratamiento.
RELATO DEL CASO: Paciente del sexo femenino, 16 años, sometida a ureterolitotripsia a laser para resección de cálculo ureteral sobre sedación y bloqueo subaracnóideo con lidocaína a 5% (50 mg). Minutos después, la paciente presentó placas eritematosas y pruriginosas en el cuello y tronco y edema discreto en las pálpebras y en los labios. Fue tratada con prometazina, con reversión completa del cuadro. Posteriormente, fue encaminada al servicio de Inmunopediatria donde fueron realizados testes de desencadenamiento alérgico. Presentó teste intradérmico positivo, siendo confirmada la hipótesis de alergia a la lidocaína.
CONCLUSIONES: La reacción alérgica a la lidocaína es rara, no obstante es necesario que los profesionales de la área de salud estén siempre alertas para esa ocurrencia.




Anaphylactic reaction to a drug is any reaction mediated by IgE antibody, specifically formed against this drug or one of its metabolytes 1. It corresponds to less than 10% drug allergic reactions 2. Allergic reactions may be classified as: type I (immediate hypersensitivity), II (cytotoxic), III (disease by immune complex) or IV (contact dermatitis). The conjugation of the antigen (drug) with IgE in the surface of mastocytes (in tissues) or of basophiles (circulating), results in anaphylaxis mediators release, especially histamine which, in turn, produces vasodilation, increased capillary patency, smooth muscles contraction and increased glandular activities 2.

Allergy to local anesthetics has for a long time been considered a pseudo-allergic or anaphylactoid reaction 3. In anaphylactoid reactions, clinically not distinguishable from anaphylactic reactions, endogenous histamine is released by non-immune mechanisms. Methylparaben, a preservative found in some local anesthetics, has been implied in anaphylactoid reactions.

Today it is known that local anesthetics may trigger allergic reactions type I (immediate hypersensitivity) and type IV (contact dermatitis) 4. Ester-type anesthetics cause hypersensitivity type IV, while amide-type anesthetics may cause both types of hypersensitivity 4. Hypersensitivity type I to lidocaine has been confirmed by the development of specific IgE antibodies against the drug and confirmed by previous studies 5-7.

In the United States, 55 thousand lidocaine injections are daily applied for dentistry practice and the real incidence of allergic reactions is still unknown 8.

In Brazil, the daily number of local anesthesias is estimated in tens of thousands, but the real dimension of adverse reactions is unknown. From all adverse reactions in dental offices, not more than 1% are allergic reactions 9.

Most adverse reactions do not involve specific immune sensitization being primarily a result of side effects, toxicity, drug interactions or psychogenic reactions 10.

This study aimed at presenting a case of allergy to spinal lidocaine.



Female patient, 16 years old, 50 kg, physical status ASA I, submitted to laser ureterolythotripsy for ureteral stone resection in January 2000, under sedation with propofol (40 mg) and spinal block with 5% lidocaine (50 mg). Minutes later, patient presented with erythematous pruriginous plaques on neck and trunk, angioedema and mild eyelid and lip edema, without bronchospasm. Patient was treated with promazetine (12.5 mg) with total reversion of symptoms.

In February 2003, when submitted to dental treatment and due to history of possible allergic reaction to local anesthetics, patient was referred by the dentist to the Immune-Pediatrics service where she was submitted to triggering tests with preservative-free lidocaine.

Prick-test was negative. At intradermal test patient has presented pruritus and erythematous plaques on trunk and abdomen. Test was interrupted and prometazine (12.5 mg) was again administered with improvement of symptoms. Diagnosis of hypersensitivity type I to local anesthetic (lidocaine) was confirmed and subcutaneous injection test was not performed. No tests were performed with other local anesthetics.



Clinical manifestations suggesting IgE-mediated hypersensitivity include pruritus, hives, bronchospasm and agioedema 2. In most cases, these events are observed in up to one hour after exposure. Other manifestations, such as dyspnea, hypotension or syncope may be IgE-mediated but most probably will be due to other mechanisms 2. Wheezing, heart failure and death have also been reported after lidocaine administration in patients with chronic obstructive pulmonary disease 8, as well as other manifestations of obscure nature, such as thrombocytopenia, fixed erythema and exfoliative dermatitis 1.

Contact dermatitis after topic use of local anesthetics is more commonly observed as compared to antibody-mediated allergic reactions 11.

Tests with progressive exposure and doses (Table I) according to a diagnostic protocol established in 1997 are used to diagnose hypersensitivity to local anesthetics 12. Test should be performed with preservative-free or vasoconstrictor-free local anesthetics and there should be a control with 0.9% saline. Following in the prick-test there are the intradermal test and the subcutaneous provocative test with incremental doses of the promoting agent or similar anesthetics (it could  be done sometimes in the operating center).

When diagnostic questions persist, a radioallergosorbent test (RAST) is performed to detect specific IgE.

Allergologic tests have their limitation, however a positive response to high dilutions is in general suggestive of hypersensitivity and alerts physicians or dentists to be careful or consider a different anesthetic agent 8.

Our patient had negative prick-test and positive intradermal test. With positive intradermal test, there has been no need to perform the subcutaneous test since increased exposure depth could bring risk for allergic events of major consequences. Radioallergosorbent test (RAST) specific for lidocaine is not performed in Brazil. So, it is only possible to infer that it is a true lidocaine allergic reaction. Diagnosis confirmation through detection of IgE against local anesthetic is needed. Since IgE half-life is very short (2 to 4 days), patients may present negative RAST even with true allergic reaction 7.

The real incidence of anaphylactic reactions to lidocaine is unknown, but there are reports on allergic reactions confirmed by high IgE levels 11,13.

Most allergic events are a consequence of toxic reactions to local anesthetics directly on central nervous and cardiovascular system and are caused by excessive dose, rapid systemic absorption or when the drug is accidentally administered into a blood vessel 14. These reactions consist of central nervous system stimulation, that is, inquietude, nausea, vomiting, disorientation, shivering, unconsciousness and seizures; when dramatically evolved, they include respiratory depression, comma, hypotension, heart failure and death 8.

Epinephrine associated to local anesthetics delays systemic absorption rate and prolongs its pharmacological effects, thus decreasing toxic reaction risks. However, epinephrine may determine exogenous sympathetic stimulation such as anxiety, tachycardia and hypertension 3.

Treatment varies according to clinical manifestation and severity of adverse reactions. Faced to a potential fatal situation, treatment should be aggressive, although in most cases, therapy is symptomatic.

Diazepam, phenobarbital and phenytoin may be used, if needed, to control seizures. Dexametazone is useful to block inflammatory response pathway through arachidonic acid. For severe angioedema oxygen, tracheal intubation, epinephrine (muscular milesimal solution 0.1 mL.10 kg-1 in maximum dose of 0.5 mL), anti-histaminics and intravenous hydrocortisone may be indicated. Intramuscular anti-hystaminics or subcutaneous epinephrine may be indicated for severe hives.

Oxygen, artificial ventilation, b2-agonists (by pulmonary route), epinephrine, hydrocortisone and intravenous aminophylline are recommended for severe bronchospasm. In the presence of severe cardiocirculatory failure, high volumes of crystalloid solution should be administered. Sodium bicarbonate is indicated for metabolic acidosis.

Allergic reactions prophylaxis aims at preventing a new contact with the drug, regardless of the administration route.

Immunoglobulins are used to passively immunize patients, preventing the development of a certain disease or allergic reaction (for example, bee poison) 15. There are no reports to date on the use of immunoglobulins to patients allergic to local anesthetics 8.

Although local anesthetics are well-tolerated drugs, faced to a clinical history of previous adverse reaction most physicians and dentists reluct in re-exposing patients before having data assuring a lower risk for these reactions, especially allergic reactions.

Allergologic tests, when adequately used, are safe and valuable to determine the anesthetic agent of choice.

Our case seemed to be a true allergic reaction, both because spinal lidocaine was used and because challenge test with preservative-free lidocaine was positive.



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Correspondence to
Dra. Liana Maria Tôrres de Araújo
Rua Napoleão de Barros, 715 4º Andar
04024-900 São Paulo, Brazil

Submitted for publication October 31, 2003
Accepted for publication January 29, 2004



* Received from Departamento de Anestesiologia da Escola Paulista de Medicina, Hospital São Paulo (HSP)

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