Overview
- Abnormal response of the body to penicillin and its degradation products
- Symptoms such as rash, fever, itching, and difficulty breathing are common
- Anti-allergic treatment is required in the acute stage, and emergency treatment is required for severe cases
- If treated in time, the prognosis is generally good without sequelae.
Disease definition
Penicillin allergy is an abnormal reaction of the body's immune system to penicillin and its degradation products. Common symptoms and signs include urticaria, fever, itching, and dyspnea.
In severe cases, anaphylactic shock and exfoliative dermatitis may occur, affecting multiple organ systems and endangering life.
Epidemiology
Allergic reactions caused by penicillin allergy, the total incidence of type Ⅰ, Ⅱ, and Ⅲ allergic reactions is 3% to 10%, and the most serious type Ⅰ allergic reaction, namely anaphylactic shock, has an incidence rate of about (0.4~1.5% of the number of people who take the drug) )/10,000, the death rate is about 0.1/10,000.
Disease type
Clinically, penicillin allergic reactions are usually divided into three categories.
Anaphylaxis
It mainly refers to type I allergic reactions, including urticaria, anaphylactic shock, laryngeal edema, and bronchial asthma, etc. Most of them occur within 1 hour, and a few can occur as late as 6 hours.
Delayed hypersensitivity reaction
Including type Ⅱ, Ⅲ, Ⅳ hypersensitivity reactions, which usually occur 1 hour after administration.
Penicillin allergy is an allergic reaction of the human body to penicillin and its degradation products. According to the etiology, it can be divided into type I, II, III, and IV allergic reactions.
Basic cause
Penicillin allergic reaction is caused by penicillin degradation products such as penicillin thiazole protein, penicramic acid, and 6-APA polymers. The body can produce antibodies within 5 to 8 days after exposure, and it will produce antibodies when it is exposed again. allergic reaction. Most drug users develop it immediately after exposure to the drug, and a few people can develop it after a few days.
Anaphylaxis
Type I hypersensitivity reaction is an immediate hypersensitivity reaction mediated by IgE immunoglobulin.
Delayed hypersensitivity reaction
- Type II allergic reaction: mainly refers to cytotoxicity, mainly causing hemolytic anemia, agranulocytosis, thrombocytopenia, etc.;
- Type III allergic reaction: mainly refers to the antigen-antibody complex reaction, mainly causing serum sickness and drug fever;
- Type IV allergic reaction: mainly refers to delayed or cell-mediated allergic reaction, mainly causing contact dermatitis, bullous exfoliation and interstitial nephritis.
Predisposing factors
People with allergies may be prone to penicillin allergy.
Different types of allergic reactions have different symptoms, which can be manifested as rash, itchy skin, fever, runny nose, and difficulty breathing. In severe cases, anaphylactic shock, exfoliative dermatitis, etc. may occur, which are life-threatening.
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Typical symptoms
Anaphylaxis
Usually occurs within minutes to an hour after administration.
- Acute urticaria: It is a kind of edematous lumps of different sizes that are limited to the surface of the skin and mucous membranes, and may be accompanied by skin itching and angioedema.
- Bronchial asthma: typically manifested as expiratory dyspnea accompanied by wheezing sounds, which may be accompanied by shortness of breath, chest tightness, and cough.
- Laryngeal edema: a critical emergency with obvious hoarseness, dyspnea, and may be accompanied by sore throat and fever.
- Anaphylactic shock: It is the most serious adverse reaction. The early manifestations mainly include mental tension or irritability, pale complexion, clammy hands and feet, tachycardia, rapid respiratory rate, normal or slightly elevated blood pressure, but small pulse compression. In the later stage, apathy, unresponsiveness, confusion or even coma, cyanosis of lips, cold sweat, thin and fast pulse, significant drop in blood pressure and smaller pulse pressure may appear. Poisoning, etc., may be complicated by disseminated intravascular coagulation (DIC).
Delayed hypersensitivity reaction
Occurs 1 hour or even days after administration.
- Skin lesions can be manifested as itching, erythematous rash, maculopapular rash, erythema multiforme, blisters, exfoliation of skin flakes, etc.
- Common non-skin lesions may include fever and serum sickness-type reactions (in addition to fever and rash, there may also be joint swelling and pain, enlarged lymph nodes, abdominal pain, etc.).
- Rare non-skin lesions may have hemolytic anemia, thrombocytopenia, acute interstitial nephritis and other corresponding hemolysis, bleeding, renal dysfunction and other symptoms.
Immediately report to the medical staff or seek medical advice if any of the following adverse reactions occur during or after the use of penicillin:
- Skin and mucous membrane symptoms such as red wheal, skin itching, and rash appear.
- When the condition is critical, such as general discomfort, numbness of lips, tongue, hands and feet, itchy throat, dizziness, palpitation, chest tightness, nausea, vomiting, irritability and other symptoms, you should seek medical attention immediately. In case of anaphylactic shock, immediate rescue is required.
- Other symptoms that may be related to allergic reactions, such as fever, gum bleeding caused by thrombocytopenia, ecchymosis on the skin, hematemesis, dark stools, and red urine; yellow staining of the skin and mucous membranes, dark urine, and urine Quantity reduction etc.
Doctors give a diagnosis and correct treatment measures based on the symptoms described by the patient, as well as the results of physical examination, laboratory tests and examinations. During your visit, your doctor may ask questions such as:
- Whether there is a history of allergies, and whether there have been similar symptoms before;
- Whether to use penicillin drugs;
- What are the main symptoms, how long have they lasted, and whether they have been relieved;
- With or without treatment, what is the effect.
Medical department
Emergency Department
Related checks
physical examination
Examine the patient for the appropriate signs of immediate and delayed hypersensitivity reactions described above.
Laboratory tests and auxiliary tests
Patients allergic to penicillin, especially those with symptoms of anaphylactic shock, need to complete the following examinations: blood routine, blood biochemical examination, blood gas analysis, coagulation function, urine and stool routine, electrocardiogram, X-ray, CT examination to evaluate the patient's condition, and differentiated from other diseases.
Penicillin skin test
This is currently the most rapid, sensitive and economical method for predicting penicillin immediate hypersensitivity reactions. The scientific and standardized penicillin skin test has a good predictive effect on immediate allergic reactions such as anaphylactic shock in adults and children, and can effectively reduce the risk of serious life-threatening diseases such as anaphylactic shock in patients.
- A negative penicillin skin test indicates that the risk of immediate hypersensitivity reactions such as anaphylactic shock is low, and penicillin-type drugs can be accepted for treatment. However, it should be noted that a negative penicillin skin test still has the risk of other immediate hypersensitivity reactions, especially at the time of first administration.
- A positive penicillin skin test indicates that the possibility of immediate hypersensitivity reactions may reach 50%, and penicillin drugs should not be used.
Special attention should be paid to the risk of severe anaphylactic reactions such as anaphylactic shock when patients undergo penicillin skin testing. At this time, rescue should be carried out in time and on the spot.
Differential diagnosis
Allergic reactions are similar to other diseases, and doctors will conduct detailed examinations to judge from many aspects, here are just examples:
- Pruritus, rash, and ulceration of the skin and mucous membranes should be differentiated from urticaria caused by other causes such as papular urticaria and contact urticaria;
- Symptoms such as dyspnea, chest tightness, and cough should be differentiated from chronic obstructive pulmonary disease and cardiogenic asthma;
- Differentiate anemia, yellowing of skin and eye sclera, enlarged spleen from other causes of hemolytic anemia;
- Symptoms of anaphylactic shock should be distinguished from septic shock, neurogenic shock, cardiogenic shock, and hypovolemic shock;
- When dysuria, low back pain or uremia symptoms occur, it should be differentiated from other causes of acute renal failure, such as acute tubular necrosis and rapidly progressive glomerulonephritis.
For penicillin allergy, prevention is the main priority. Before using penicillin, a skin test should be performed. When an allergic reaction occurs, the drug should be stopped immediately and anti-allergic treatment should be carried out. In severe cases, emergency treatment should be carried out immediately.
Acute treatment
When an allergic reaction to penicillin occurs, the drug should be discontinued immediately, the patient’s re-exposure to penicillin drugs should be quickly blocked, vital signs should be monitored, intravenous access should be established as appropriate, and antihistamines, glucocorticoids and other drugs should be given for anti-allergic treatment.
- Anaphylactic shock: Oxygen inhalation, ECG monitoring; rapid volume expansion and fluid replacement; intramuscular or subcutaneous injection of adrenaline; administration of glucocorticoids, antihistamines and other drugs and supportive treatment.
- Laryngeal edema: keep the airway open, solve dyspnea, give oxygen, and perform cricothyroidotomy or tracheotomy if necessary.
- Carry out cardiopulmonary resuscitation immediately when the heartbeat and breathing stop; endotracheal intubation and mechanical ventilation; pay attention to the functions of various organs and maintain water and electrolyte balance.
- Severe hemolytic anemia: transfusion of washed red blood cells; optional antihistamines to reduce rash/urticaria, vitamin C and calcium can be used in combination with antihistamines to improve vascular permeability.
Medical treatement
Due to large individual differences, there is no absolute best, fastest, or most effective medication. Except for commonly used over-the-counter drugs, you should choose the most appropriate drug based on your personal situation under the guidance of a doctor.
Common treatments for penicillin allergy
- Antihistamines (such as diphenhydramine, promethazine, chlorpheniramine, loratadine, etc.): are currently the most widely used non-specific antiallergic drugs, which can antagonize the binding of histamine to H1 receptors, thereby Inhibit the occurrence of allergic reactions.
- Short-acting β2-receptor agonists (such as albuterol): These drugs can stimulate β2-receptors, relax bronchial smooth muscle, and reduce asthma symptoms.
- Glucocorticoids: Bronchospasm can be relieved by inhalation/nebulization formulations, and oral/intravenous glucocorticoid system can be used for short-term treatment if systemic symptoms are severe.
Drugs commonly used in the treatment of anaphylactic shock
- Epinephrine: The drug of choice, with massive and rapid fluid resuscitation.
- Glucocorticoids: second-line drugs, not the first choice for rescue. Hydrocortisone succinate or methylprednisolone are preferred.
- Antihistamines (such as diphenhydramine, promethazine, chlorpheniramine, etc.): second-line drugs, not the first choice for rescue. It is used to improve skin and mucous membrane symptoms such as dyspnea and rash.
- Short-acting β2-receptor agonists (such as albuterol): second-line drugs for rescue, used to relieve bronchospasm and improve dyspnea symptoms.
During the course of treatment and after recovery, attention should be paid to drug cross allergies, such as cephalosporin antibiotics and penicillin cross allergies.
Penicillin allergic urticaria usually resolves spontaneously within 24 hours after stopping the drug. The rescue treatment of penicillin allergy is timely, and usually there is no sequelae after recovery. Severe allergic reactions can cause organ dysfunction and even death.
Complication
It mainly occurs in patients with severe allergic reactions, and complications such as infection, respiratory and circulatory failure, acute renal failure, and disseminated intravascular coagulation may occur.
Before using penicillin, it should be clear whether there is a history of penicillin allergy, and patients with unknown allergy history should have a skin test before use.
Daily Condition Monitoring
Pay attention to whether there are symptoms of delayed hypersensitivity reaction, and seek medical treatment in time if it occurs.
Special considerations
Commonly used penicillin drugs include penicillin G, benzathine penicillin, amoxicillin, ampicillin, piperacillin, and sulbenicillin. If you are allergic to one of them, you will also be allergic to the rest, but the degree of allergic reaction is different. one.
Due to the similarity in the chemical structure between cephalosporins and penicillins, some of them may have certain cross-allergic reactions. If the patient has an allergic reaction to penicillins in the past, it is not recommended to use cephalosporins without authorization. A professional physician should be consulted for a detailed assessment, and an emergency plan for all rescue measures should be prepared during use.
Prevention
Patients with a history of penicillin allergy should avoid using penicillin antibiotics. For patients who have no history of allergies or do not know whether they are allergic, a skin test should be performed before using penicillin drugs, and they can be used only if the skin test is negative.
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