Criteria for judging positive cephalosporin skin test

Cephalosporins are a type of antibiotic that has become more common in recent years. It has a wide range of uses and can treat a variety of diseases. The drugs that have better market performance in pharmacies include cefuroxime, cefixime, and cefradine. In chronological order of their drug invention, cephalosporins are divided into first, second, third and fourth generations. Patients need to pay special attention to not taking cephalosporins before or after drinking, otherwise they may easily experience fainting, shock, and even life-threatening situations. Some people are allergic to ceftriaxone and need a skin test before taking it.

1. What is a skin test?

Skin test is the abbreviation of skin (or intradermal) sensitivity test and is the most commonly used specific test in clinical practice. Certain drugs are prone to allergic reactions during clinical use, such as penicillin, streptomycin, cytochrome C, etc. Common allergic reactions include rash, urticaria, dermatitis, fever, angioedema, asthma, anaphylactic shock, etc. Among them, anaphylactic shock is the most serious and can even lead to death.

2. Drugs that require skin testing

Drugs that require skin tests are divided into two types: one type is drugs that must be tested according to regulations; the other type is drugs that only require skin tests under specific circumstances. There are two situations in which skin tests are required for drugs: one is routine skin test drugs, including penicillins (injectable and oral formulations), streptomycin, tuberculin, tetanus antitoxin serum, procaine hydrochloride, cytochrome C, organic iodine contrast agents, and asparaginase. Regardless of whether the drug instructions state that a skin test is required, these drugs must be skin tested before use. The other type is drugs that are prone to allergies, but the drug instructions require skin tests (non-routine skin test drugs), such as: Zhongnuojialin (ceftazidime sodium; Lifen is also ceftriaxone sodium, but the instructions do not require skin tests), Qingkailing (lyophilized powder injection), Yitixin (ceftazidime sodium), chymotrypsin, vitamin B1 injection, thymosin injection (people with allergic constitution need to do skin tests).

3. Criteria for judging a positive cephalosporin skin test

The principle of cephalosporin allergy skin test is actually similar to that of penicillin. Generally, a redness less than or equal to 2 cm is considered negative. However, it also depends on the patient's skin sensation, such as whether the skin in the skin test area is itchy, whether there is an allergic rash around it, etc.

4. Symptoms and treatment of cephalosporin skin test allergy

Common allergic reactions to cephalosporins include rash, drug fever, urticaria, etc., with the former being the most common. Mild cases do not require treatment, while severe cases can be appropriately treated with antihistamines and corticosteroids. The most serious is anaphylactic shock, which is rare in clinical practice. If not treated in time, it can lead to death. The treatment of anaphylactic shock mainly includes oxygen inhalation, maintaining airway patency, the use of a series of vasoactive drugs such as epinephrine, and symptomatic supportive treatment.